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### Tennyson’s Wrinkled Feet: Ageing and the Poetics of Decay

Author: Jacob Jewusiak (Newcastle University)

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## Abstract

This article argues that Tennyson’s ‘Tithonus’ (1860) draws together ageing and decay through the poem’s formal wrinkling: moments where metrical disruption, folding, slackness, or concealment correspond to the insights derived from the perspective of great age — chiming the poet’s keynotes of disappointment, mourning, and loss. I turn to ‘Ulysses’ (1842) and ‘The Lotos-Eaters’ (1832) — poems with a similar, though differently stressed, investment in age and decay — to demonstrate the political stakes of this thesis. While for Ulysses old age presents the triumphant opportunity to live ‘Life to the lees’, this arises from a sense of masculine anxiety about imminent decay. ‘The Lotos-Eaters’ positions ageing and decay against the imperative to work as a means of decentring the monolithic temporality of capitalist utility. These poems theorize the poetics of rot as a senescent challenge to the masculine and capitalist assumptions about the inherent value of mastery, productivity, and vigour.

Keywords: Tennyson, Tithonus, Ulysses, The Lotos-Eaters, old age, decay

How to Cite:

Jewusiak, J., (2021) “Tennyson’s Wrinkled Feet: Ageing and the Poetics of Decay”, 19: Interdisciplinary Studies in the Long Nineteenth Century 2021(32). doi: https://doi.org/10.16995/ntn.3466

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A ‘gray shadow, once a man’, the immortal Tithonus of Tennyson’s poem grows older — forever.1 While the gods remain impervious to the depredations of time, the ‘strong Hours indignant work’d their wills’ into Tithonus’s ageing body, leaving him a ‘white-hair’d shadow’, ‘wither[ed]’, ‘maim’d’, ‘wasted’, and ‘marr’d’ (ll. 18, 8, 6, 20, 19). ‘Consume[d]’ by the years, Tithonus’s battered body shrinks into itself, drawing upon an ageist lexicon of decay that has long been used to describe old age (l. 6). The projection of decay onto the older human body usually has overwhelmingly negative connotations: putrefaction and abjection go hand in hand, as the process of decomposition takes on morally repulsive overtones. When decay is mapped onto old age, senescence takes on a similarly negative charge as a feared interval of the human lifespan. Martha Nussbaum posits that the stigma associated with the ageing of others — the view of the ‘aging body […] as a site of decay and future death’ — arises from the fear of it happening to oneself.2 ‘We reject’, Nussbaum writes, ‘all that is associated with decay and mortality: […] decaying mortal animality’ (p. 110). For age critics such as Margaret Gullette, projecting the negative connotations of decay onto the human body is a structural prejudice that must be overcome. She writes that ‘instead of persistently yoking this fear to the end of life and bodily decay, we do better to conceive of aging at any age as an issue of consciousness and a relationship to personal change’.3 In an analysis of three poems by Tennyson — ‘Tithonus’ (1860), ‘Ulysses’ (1842), and ‘The Lotos-Eaters’ (1832) — I argue that, even as the poet retains the connection between decay and ageing, he recodes the process of putrefaction as ecologically and existentially valuable. The poems hold up the world of decay and renewal against that of immortality and sterile repetition: by valuing the former, Tennyson dissociates old age with disgust while avoiding the opposite pole of repressing physiological change. Doing so unsettles many of the entrenched biases against old age, which the poet affirms as a productive interval rather than a nightmarish inevitability.

The professional medical discourse of the late eighteenth and nineteenth centuries helped to shape the cultural narrative connecting ageing and decay. Some physicians theorized that each person was imbued with a limited amount of vital power that decreased over time. Charles Hufeland developed this view in his influential Art of Prolonging Life (1797), positing that ‘by the assistance of the vital power a body is transferred from the mechanical and chemical world to a new one, the organic or living world’.4 Sparking matter into organic life, the finite reserves of vital power must be carefully preserved:

The energy of life, therefore, will be in an inverse ratio with its duration; or the more intensively a being lives, the more will its life lose in extension. […] If the intensive life of a plant be increased by heat, manure, and artificial means, it will expand itself to perfection more rapidly, but it will also soon decay. (p. 34)

In A Dictionary of Practical Medicine (1834) the Scottish physician James Copland deploys the vitalist metaphor of the burning flame to describe the lifespan: ‘the oil with which the lamp of human, and indeed all animal, existence burns is filled at its commencement, and is never afterwards supplied; and that the more brilliant the flame, the shorter will be its duration.’5 This popular belief about the expendability of one’s life force cultivates the belief that ‘age […] may be considered as commencing when the vital energies of the different organs begin to decline, — when the maturity of life glides into decay’ (Copland, I, 44). For the polymath P. M. Roget — physician, theologian, lexicographer — growing older constitutes a battle between the conservative and destructive forces of the human body: once the scales tip towards decline, one ‘transition[s] from maturity to decay’: ‘living bodies perish from within, being consumed by the very fire which is itself the source of their animation.’6 The propagation of vitalist theory in the medical writing of the era conjures an image of ageing — especially in the later years of life — as a process of relentless decay of an original source.7

The notion that decay is an inevitable and lamentable aspect of growing older continued to inform early studies of culture and age, such as Simone de Beauvoir’s The Coming of Age (1970). For a philosopher so sensitive to the myriad ways patriarchal culture marginalizes women, her account of age remains surprisingly tethered to ‘biological facts’:

For every individual age begins with it a dreaded decline. It is in complete conflict with the manly or womanly ideal cherished by the young and the fully-grown. The immediate, natural attitude is to reject it, in so far as it is summed up by the words decrepitude, ugliness and ill-health. Old age in others also causes an instant repulsion. This primitive reaction remains alive even when custom represses it.8

Age fundamentally shapes the epistemological contexts of daily life, and its ability to organize bodies draws a great deal of power from the fact that it often goes unquestioned: the decline narrative of ageing is naturalized by a sense of biological inevitability.9 Thus, ageing’s normative patterns: the young are beautiful, full of potential, and difficult to control; the aged are ugly, out of time, and predictable. According to pervasive stereotypes, the young are characterized by growth, the old by decay. Beauvoir’s emphatic assertion that ageing is like decay draws upon rot’s association with what Jamie Lorimer defines as ‘stagnation, slowness, and disease […] mortality, vulnerability, and the inevitability of death’.10 The signification of decay in ecological and cultural discourse has been historically and semiotically linked to the abjection of ageing as a transformative process.

Recent scholarship provides new models for conceptualizing decay as a positive agent in ecological, economic, and aesthetic contexts. In a recent special issue on the subject in the journal Configurations, the editor asserts that ‘rot and decay […] are often met with irrational disgust through which their ecologically valuable functions become obscured, their role in a complex system overshadowed by what can be regarded only as an affective response’.11 Joanna Radin writes, in her piece titled ‘Rot’, that ‘processes of putrefaction are powerfully generative. They provide epistemologically rich opportunities to conjure multispecies worlds and with them alternative visions for what it means to be alive.’12 In his reading of Tennyson’s In Memoriam, John MacNeill Miller attends to the decomposing body of Arthur Hallam that many critics have overlooked: by ‘obscuring rot’, he argues, ‘we obscure ecological realities, turning our backs on a vital connection between individual human beings and the broader biotic community of which we are a part’.13 However, the affective response to decay — which is often sublimated into moral repugnance — lags behind this scholarly affirmation of decay’s centrality in forming networks. Most can intellectually register decay’s significance, but fewer can condition their response to a process long associated with threatening the integrity of organic matter and life itself.

The projection of decay onto a context like ageing requires a slippage between its literal and figurative modes. The application of the term has less to do with the physical signs of rot — such as necrosis — and more with conjuring a set of feelings produced in the observer of decay: fear of the flesh’s disintegration, its mephitic odours and iridescent blooms of colour. Expanding the dominion of putrefaction beyond that of inorganic matter — so that it metaphorically seeps into the living flesh of the aged — attests to decay’s nightmarish expansiveness: its messy ability to spill over into the realm of the figurative.14 Such boundary crossing suggests an ontological difficulty in determining when decay begins and ends. In her reading of John Ruskin’s The Ethics of Dust, Ella Mershon writes that decay is more than what ‘happens to the body […] after it dies. Decay is with us every step of the way. It is a “daily” process, as much an “operation” of life as of death.’15 The theorist Reza Negarestani avers that ‘it becomes increasingly difficult to say when the process of decay ceases to exist and is supplanted by complete ontological annulment or extinction’.16 Decay is commonly understood to follow a strong teleology — where one type of privileged matter transforms into a lesser form. But decay rarely occurs within such a clearly marked trajectory. Instead of policing the boundaries of decay, a lexicon derived from intensity — the pace of putrefaction, the affective rhythm of rot — better captures the role of decay in stimulating metamorphosis, of generating new configurations and forms of matter rather than simply destroying them.

The intensity of decay resonates with the way Tennyson’s poetry draws words into temporal and acoustic arrangements that provoke a confrontation with the quiddity of language — a way of bodying forth, through the poem’s form, a new orientation towards rot. I argue that ‘Tithonus’ affectively registers a thematic focus on ageing and decay through its use of what I call formal wrinkling: moments where metrical disruption, folding, slackness, or concealment correspond to the insights derived from the perspective of great age — chiming the poet’s keynotes of disappointment, mourning, and loss. I turn to ‘Ulysses’ and ‘The Lotos-Eaters’ — poems with a similar, though differently stressed, investment in age and decay — to demonstrate the political stakes of this thesis. While for Ulysses old age presents the triumphant opportunity to live ‘Life to the lees’, this arises from a sense of masculine anxiety about imminent decay.17 ‘The Lotos-Eaters’ positions ageing and decay against the imperative to work as a means of decentring the monolithic temporality of capitalist utility. Through an analysis of these three poems, I suggest that Tennyson theorizes the poetics of rot as a senescent challenge to the masculine and capitalist assumptions about the inherent value of mastery, productivity, and vigour.

## Forever old

Addressing the tenacity of the vitalist ‘fallacy […] that senescence arises from the depletion of some necessary reserve’, George Williams uses the term ‘Tithonus error’ in his critique of modern gerontology’s ‘preoccupation with death, as if it were a programmed event in an organism’s life history’.18 Yet even before ‘Tithonus’, Tennyson’s poetry displayed an interest in the tension between the terminal point of death and modes of lingering such as decay. Written when he was between fourteen and sixteen years old, The Devil and the Lady (1824) pivots on the January–May marriage between the young Amoret and her elderly husband, Magus. With almost sixty years intervening between them, Amoret imagines her husband’s desiccated body stubbornly persisting across the years:

He bears a charmed life and will outlast me
In mustiness of dry longevity.
Like some tough mummy wither’d, not decay’d —
His years are countless as the dusty race
That people an old Cheese and flourish only
In the unsoundest parts on’t.19

Anticipating the representation of Tithonus’s body in Tennyson’s mature poem, Magus remains painfully preserved through enchantment — a dry, rather than slimy, doom that conjures anger or sympathy rather than disgust. Amoret apostrophizes Magus as a ‘crazy dotard, crusted o’er with age’ and ‘a shrunken, sapless, wizen Grasshopper’ (ll. 5, 7). The reference to the grasshopper’s husk recalls the conclusion of the Tithonus myth, where the long-suffering lover finally achieves respite through his metamorphosis into an insect.20 The bodies of Tennyson’s aged characters grow older but resist decay in ways that confound the expectation of deterioration projected upon them.

‘Tithonus’ begins with the speaker’s weary recognition that nature’s patterns of decay do not apply to his own persisting body, which remains exiled from the meaningful closure of natural rhythms:

The woods decay, the woods decay and fall,
The vapours weep their burthen to the ground,
Man comes and tills the field and lies beneath,
And after many a summer dies the swan. (ll. 1–4)

Observing the earthy cycles that draw matter back into the ground — as trees, vapours, men, and swans wilt downward into the soil — Tithonus longs for the inevitable termination that attends organic matter: ‘Release me, and restore me to the ground’ (l. 72). While Tithonus’s desire takes the form of a gravitational pull towards the quiet earth, the poem also contains upward vectors of movement. He associates this movement with his lover Aurora, bitterly recalling the days of courtship when he ‘heard Apollo sing, | While Ilion like a mist rose into towers’ (ll. 62–63). Every morning, ‘when the steam | Floats up from those dim fields’, memorializes the distance separating him from the days of his happy youth (ll. 68–69). This upward movement of steam and mist captures the Enlightenment’s dissociation of the body from mind and rationality: to the accompaniment of Apollo, the towers of the city rise and give shape to the dawn of modernity. Yet the visual and auditory spectacle excludes Tithonus, who remains on the margins of this triumphant narrative begging for the decomposition into mute matter.

Tithonus does not merely desire death, but the transformative process of decay. This distinction is significant since scholars often mistakenly use the term ‘decay’ to describe the speaker’s condition in the poem.21 If Tithonus was already in a state of decay, he would not begin his monologue by yearning for decomposition — exemplified in the repetition of ‘the woods decay’ in the first line, the vapours of the second, and the fertilizing corpse of the third. This problematic logic informs Cornelia Pearsall’s account of ‘Tithonus’, which begins by asserting that the speaker is ‘in a material state of unending decay’ and ends with the claim that ‘Tithonus expresses his desire to become particulate. […] [He] envisions an afterlife of compost.’22 Michael Greene makes a similar claim that ‘the repetition in line 1, “The woods decay, the woods decay and fall”, suggests tired senility. Tithonus’ impotence finds its correlative in the falling and decay of the wood.’23 Yet surely Tithonus cannot desire to decay and be in a state of decay at the same time. The inconsistency arises from the pervasive use of decay as a synonym for the process of ageing. Doing so perpetuates an ageist equivalence that obscures Tennyson’s rigorous separation of the two processes in the poem. Tithonus’s ageing is pathological precisely because it lacks the temporal attributes that he jealously ascribes to the rotting matter of the poem’s first lines.

Tithonus contrasts his desire for decay with his youthful infatuation for Aurora, who flames the sky into dawn every morning. As the dawn ‘redden[s]’, her ‘sweet eyes brighten’ and ‘dim curls kindle’, and she departs before answering Tithonus’s plea for death, leaving behind only ambiguous ‘tears’ that he interprets as the mute confirmation of his doom: ‘The Gods themselves cannot recall their gifts’ (ll. 37, 38, 54, 49). Her association with light and air makes her both beautiful and capricious, like the wantonly blooming spring:

Mouth, forehead, eyelids, growing dewy-warm
With kisses balmier than half-opening buds
Of April, and could hear the lips that kiss’d
Whispering I knew not what of wild and sweet. (ll. 58–61)

Aurora’s fecundity takes on the characteristics of an erogenous and yet oppressively humid saturation, a ‘wild and sweet’ irresponsibility — of tears that can mean regret, sorrow, condescension, or condensation — that contrasts with the dry predictability of Tithonus’s existence. Entrapped within his gloomy durability, Tithonus laments that the dawn’s radiance leaves him ‘cold’:

Coldly thy rosy shadows bathe me, cold
Are all thy lights, and cold my wrinkled feet
Upon thy glimmering thresholds, when the steam
Floats up from those dim fields about the homes
Of happy men that have the power to die. (ll. 66–70)

The brilliance of dawn’s arrival does not touch the speaker, whose clammy flesh remains unaffected by the warming rhythms of renewal. The use of enjambment in these lines formalizes the speaker’s asynchrony with the pulse that animates the world around him, emphasized by such arrhythmias as the trochaic substitutions that begin lines 66 and 69. The speaker only returns to the stability of the end-stopped line when he reflects on the ‘happy’ ‘power to die’.

The ‘cold […] wrinkled feet’ of Tithonus entwine the speaker’s self-consciousness of his physical inadequacy with the senescent quality of Tennyson’s poetics. This arises in part through the metrical diminution of the concept of immortality. Early in the poem Tithonus complains that ‘Me only cruel immortality | Consumes’, and he rues his misguided demand that Aurora ‘Give me immortality’ (ll. 5–6, 15). Later, he imagines the temporality of eternal life as a humiliating aggressor:

And tho’ they could not end me, left me maim’d
To dwell in the presence of immortal youth,
Immortal age besides immortal youth,
And all I was in ashes. (ll. 20–23)

Tithonus’s description of longevity changes modes. ‘Immortality’ suggests an abstract, external condition: a disease masquerading as a gift. Later, it takes on the quality of an identity: Tithonus is an ‘immortal’, albeit one who compares unfavourably with the gods. The shift in meaning corresponds to a shift in the stress of the word. Where ‘immortality’ glides over the deathly syllable ‘mort’, ‘immortal’ places emphasis directly upon it. This change reflects Tithonus’s youthful ignorance of death’s meaningful pause and his later confrontation with its painfully resounding absence.

Written in blank verse, the monologue nevertheless undermines the heartbeat that pulses in its use of iambic pentameter, conjuring the sense of wrinkling, withering, and diminishment through manipulation of the poem’s form. Herbert Tucker describes ‘Tithonus’ as the ‘most soundproof’ of Tennyson’s monologues, an effect produced through the hushed, oneiric atmosphere of the ‘ever-silent spaces of the East’ (pp. 256, 259). The seventh line — ‘Here at the quiet limit of the world’ — replaces the first iamb with a trochee, adding emphasis to the first syllable of ‘quiet’ and creating an aural effect that contrasts with the hushed meaning of the word. The most metrically ambiguous lines correspond to the speaker’s apostrophe of Aurora, which pivots on the failure of communication:

Lo! ever thus thou growest beautiful
In silence, then before thine answer given
Departest, and thy tears are on my cheek. (ll. 43–45)

While line 43 begins with a staggering spondee, the quiet that follows reflects the muted quality of Aurora’s visual beauty. The lines add the archaic suffix to ‘growest’ and ‘Departest’, which evoke the impermanence of dawn’s splendour, whose brief interval — like the single syllable of ‘given’ that ends line 44 — gains poignancy through an illuminating compression of time. The slack syllables place additional stress on what follows, an animating tension of expansion and contraction — rooted in the rhythms of growth and decay — that Tithonus’s immortal homogeneity lacks. The poem creates a sense of wrinkling through its use of metre, conjuring aural effects that link the poem’s representation of ageing to processes of temporal folding.

This wrinkling not only occurs at the level of prosody, but also of perspective. Great age enables a sense of temporal scale that Tennyson deploys in his earliest published poetry, experimenting with the perspective of a reflective old man in the poem ‘Memory’ in Poems by Two Brothers (1827):

Days of youth, now shaded
By twilight of long years,
Though bathed in sorrow’s tears:
Thoughts of youth, which waken
Mournful feelings now
Fruits which time hath shaken
From off their parent bough.24

Tennyson creates a wrinkling effect in this lyrical triangulation of the poet’s youth through the prism of the elderly imagination, folding youth upon itself across the fulcrum point of old age: a perspectival shift that follows the weave of the poem’s cross-rhyming quatrains.25 Age also enables the bitter retrospect in ‘Remorse’, as the speaker claims, ‘Oh! ’tis a fearful thing to glance | Back on the gloom of mis-spent years’.26 Such melancholy strains of lost time are amplified through the backward glance of old age. Rather than provide a sense of fulfilment, this vantage point strikes the mournful note that resonates throughout much of Tennyson’s oeuvre: a heightened consciousness of something irretrievably lost.

This wrinkled perspective — where the time folds upon itself — was central to the composition history of ‘Tithonus’, which the poet originally wrote as ‘Tithon’ in 1833 as one of his many responses to the death of his beloved friend, Hallam. Tennyson revised the poem twenty-seven years later for publication in Thackeray’s Cornhill Magazine, extending and nuancing the speaker’s reflections upon mortality and time. In her analysis of the discrepancy between the two poems, Linda Hughes writes that ‘in 1860, […] now distanced from his loss by more than a quarter of a century, he could simultaneously explore a longing for death (the germinal impulse supplied by “Tithon”) and an acceptance of death’.27 For Hughes, the healing power of time results in a more positive stance towards the finality of death. Yet it is more than just passing time that inspires Tennyson’s revisions. The duration between 1833 and 1860 takes on the embodied form of ageing, which plays a fundamental role in the transformation of both the poet and the poem. The interval between the 24-year-old poet who wrote ‘Tithon’ and the 50-year-old who wrote ‘Tithonus’ forms another perspectival wrinkling that folds across the impossibly aged body of the mythological figure.

A significant wrinkle occurs in the way the two poems conjure the alienating effects of ageing through the speaker’s reflections on his dim youth. As we see in ‘Tithon’:

Ay me! ay me! with what another heart,
By thy divine embraces circumfused,
Thy black curls burning into sunny rings,
With thy change changed, I felt this wonderous glow.28

Tithon posits a gap between the narrating voice and the narrated — ‘what another heart’ — by contrasting it with the centripetal transformation of love: the closed circuit of ‘curls’, ‘rings’, and ‘embraces’. Old age, however, distances and differentiates — Tithon exists alone, roaming the dusky hinterlands of the East. Tennyson’s revision in 1860 extends Tithonus’s loneliness into a radical self-division across time:

Ay me! ay me! with what another heart
In days far-off, and with what other eyes
I used to watch — if I be he that watch’d —
The lucid outline forming round thee. (ll. 50–53)

Here, the ancient speaker pushes harder on the discontinuity of his identity across time. His reference to ‘eyes’ that ‘watch’ projects the visual gap of perception — between a seeing eye and its object — onto the unfathomable distance between his older and younger selves, resulting in the existential uncertainty of ‘if I be he that watch’d’.29 Moreover, this is the only stanza in ‘Tithonus’ that retains the ‘Ay me! ay me!’ that appeared in three of the original’s six stanzas, an expression of the speaker’s self-pity that triangulates ‘Ay’ through the pun on ‘I’ and ‘eye’. The revisions mark a studied intensification of the ability for old age to stretch time, wrinkle it, and defamiliarize it. Tithonus becomes a memory that no longer belongs to himself.

As the ancient speaker undergoes this process of depersonalization, he increasingly identifies with the brute materiality of the ‘dark earth’ and ‘dark world where I was born’ (ll. 48, 33). The poem concludes with a celebration of the ‘grassy barrows of the happier dead’ and the soil that contains them (l. 71):

Release me, and restore me to the ground;
Thou seëst all things, thou wilt see my grave:
Thou wilt renew thy beauty morn by morn;
I earth in earth forget these empty courts,
And thee returning on thy silver wheels. (ll. 72–76)

The speaker’s insistence on transforming back into earth problematizes one of the most repeated claims about the poem — that its central theme is the tension between life and death, impermanence and immortality. Significantly absent from this conversation is Tithonus’s desire to decompose. Rather than flashing out of existence, his imagination lingers on the metamorphosis of his body into the particulate matter of soil: his restoration ‘to the ground’. This view resonates with Charles Hufeland’s vitalist account of organic matter, where death does not mark the end of life but its dissemination into a network of putrefactive possibilities:

No sooner is a body thus decomposed than its fine particles begin to be again animated in a thousand small worms […] and, by a few changes, become, a year after, component parts perhaps of as perfect a human being as that which they appeared to corrupt. Their apparent death was only a transition to a new life. (Hufeland’s Art, p. 25)

The negative connotations associated with decay may obscure the fact that Tithonus also ascribes its qualities to Aurora, whose beauty — like the woods that repetitively decay and fall — requires the interval of darkness to draw forth the brilliance of her light. ‘Thou wilt renew’ he says in line 74, juxtaposing — with the pun on ‘wilt’ — the entwined themes of decay and rebirth. His question to Aurora — ‘How can my nature longer mix with thine?’ — not only refers to the unbridgeable gap between the two former lovers, but the impossibility for his immortal body to decay in the same way as the dawn changes into evening (l. 65). Only when Tithonus becomes nature — when he becomes ‘earth in earth’ — will he eradicate the agonizing distance from Aurora by decomposing into a restful memorial of dust she will pass every morning.

In selfishly desiring to lift himself above the vicissitudes of decay, the younger Tithonus asks for the immortality that he tragically receives. For scholars such as Geoffrey Ward and David Shaw this immortality results in paralysis: Tithonus’s actions are ‘in truth stasis’ and ‘locked in time’.30 However, Tithonus does not lament the lack of time, but its surfeit. His immortality causes his body to change constantly, forever — subject to the ravages of the strong hours that relentlessly destroy his frame. His lust for decomposition throughout the poem, therefore, is not to recover his temporal nature, but to place himself within a teleological structure — out of the terrifying prospect of endlessness, and into the comforting knowledge of putrefaction’s transformative possibilities:

Why should a man desire in any way
To vary from the kindly race of men
Or pass beyond the goal of ordinance
Where all should pause, as is most meet for all? (ll. 28–31)

The visual impression created by lines 28–30 reflects the homogeneity longed for by the speaker, while line 31 contradicts this by spilling over the bounds set by the previous lines. The caesura in line 31, which arrives after three and a half lines of breathless exposition, forcefully enacts the pause recommended by Tithonus. As the line continues for another six syllables after this pause, it suggests that the end longed for by Tithonus is not static but dynamic, enmeshed in networks of decay that ‘meet’, a term that registers both a zone of conjunction and a pun on the flesh.

## Ageing and the politics of decay

Like ‘Tithonus’, Tennyson’s poem ‘Ulysses’ shares an investment in the aesthetics of age. It is well known that Tennyson intended ‘Tithon’ to serve as a pendant — in the sense of both ‘reflection and reversal’ — to ‘Ulysses’ (Boynton, p. 232). The two old speakers have radically different perspectives on ageing: where Tithonus desires the transformative pause, Ulysses scorns it: ‘How dull it is to pause’ (l. 22). Where Tithonus’s gray shadow no longer identifies as human, the ‘gray spirit’ of Ulysses still ‘yearn[s] in desire’ (l. 30). Tithonus suffuses his lament with the imagery of decay, while Ulysses speaks his lines into the bracing sea air: ‘There lies the port; the vessel puffs her sail: | There gloom the dark, broad seas’ (ll. 44–45). Like ‘Tithonus’, ‘Ulysses’ draws inspiration from the great age of its speaker — an aspect missing from the poem’s epic source material. Eric Auerbach argues that the Greek epic’s commitment to the representation of a completely externalized, ‘uniformly illuminated, uniformly objective present’ excludes the multiple planes of existence implied by the process of ageing.31 He writes that, for heroes like Achilles and Odysseus,

their emotions are constantly displayed in their words and deeds — but they have no development, and their life-histories are clearly set forth once and for all. So little are the Homeric heroes presented as developing or having developed, that most of them […] appear to be of an age fixed from the very first. Even Odysseus, in whose case the long lapse of time and the many events which occurred offer so much opportunity for biographical development, shows almost nothing of it. Odysseus on his return is exactly the same as he was when he left Ithaca two decades earlier. (p. 17)

The epic’s exclusion of ageing marks its disposition to the real. In its profusion of details and context, but lack of inward development, the form does not aim to supplant reality but to escape it: to ‘make us forget our own reality for a few hours’ (Auerbach, p. 15). ‘Ulysses’ pivots on exactly the kind of development missing from its epic progenitor: where Auerbach claims that ‘time can touch the latter [Odysseus] only outwardly’, the weight of his accumulated years form the very pith of Tennyson’s Ulysses (p. 18).

The prospect of decay confers urgency to Ulysses’ monologue. Unlike the crippling lack of urgency that arises from Tithonus’s immortal languor, Ulysses restlessly anticipates every future moment as precarious and precious:

        every hour is saved
From that eternal silence, something more,
A bringer of new things. (ll. 26–28)

Far from resulting in resignation and apathy, Ulysses’ old age provokes a breathless rush to make the most of the time allotted to him: ‘How dull it is to pause, to make an end, | To rust unburnish’d, not to shine in use!’ (ll. 22–23). The force of decay, represented through the oxidation and dulling of the blade, forms the threat of emasculation that hovers over the poem — an anxiety about impotence that infuses Ulysses with a manic desire for more experience. While he does not desire decay like Tithonus, Ulysses does not fear it: it is a spur to action, the intimation of inevitability that calls upon him to live life immediately, intensely, ravenously: ‘All times I have enjoy’d | Greatly, have suffer’d greatly’ (ll. 7–8). That ‘little remains’ of his life does not serve as a provocation to melancholy but a call to arms (l. 26).

Ulysses’ reaction against the forces of decay arises from a stereotypical feminization of old age. The poem begins with everything that the speaker wants to escape, crystallized through the adjectives that cluster around his ‘aged wife’ in the first three lines: ‘idle’, ‘still’, and ‘barren’ (ll. 1, 2, 3). He finds the unreflective pleasures of rest revolting: the hoarding, sleeping, and feeding of ‘Life piled on life’ (l. 24). He recognizes that even the expansive immortality of Tithonus is ‘too little’ if it passes smoothly, without incident (l. 25). Ulysses allots to Telemachus the ‘common duties’ of domestic governance — ‘by slow prudence to make mild | A rugged people, and thro’ soft degrees | Subdue them to the useful and the good’ (ll. 40, 36–38) — for himself, the heaving seas of crisis and event. Andrea Charise identifies a strain of Romanticism arising from Thomas Malthus that privileges senescence over youth ‘as a viable, therapeutic, even consummate state of embodiment’.32 Ulysses’ monologue similarly inverts the age ideology that views the lifespan as a parabola that peaks in vigorous adulthood and declines into quiet and non-productive senescence:

        My mariners,
Souls that have toil’d, and wrought, and thought with me —
That ever with a frolic welcome took
The thunder and the sunshine, and opposed
Free hearts, free foreheads — you and I are old;
Old age hath yet his honour and his toil;
Death closes all: but something ere the end,
Some work of noble note, may yet be done,
Not unbecoming men that strove with Gods. (ll. 45–53)

Addressing his fellow mariners with reflections on past adventures filled with bluff, masculine labour, the speaker abruptly transitions into the present after the dash in line 49: ‘you and I are old’. The word ‘Old’ immediately follows at the beginning of the next line, registering Ulysses’ obsessive circling back to this fact of his present condition. In contrast to the examples of heroic maturity, Ulysses’ apologia for old age deploys conjunctions that suggest the persistent stereotypes of ageing: the use of ‘yet’ in lines 50 and 52 and ‘but’ in line 51 tacitly mark the speaker’s recognition of his auditors’ disbelief in the resilience of age. Line 53 would surely be written in the positive rather than negative mode for the young Ulysses — the ‘Not unbecoming men’ of the older sailors would be revised to something like ‘And becoming of men’ for the intrepid youth. As such, ‘unbecoming’ chimes the note of decomposition even as Ulysses argues defiantly against it.

What is often read as a fierce rebuttal of decline displays a great deal of repressed anxiety about ageing. The same urgency that propels Ulysses back into the fray of adventure often comes accompanied with violent rhetoric:

        Come, my friends,
’Tis not too late to seek a newer world.
Push off, and sitting well in order smite
The sounding furrows. (ll. 56–59)

Resisting the belatedness of age results in an overcompensating smiting of the sea, an unconquerable antagonist that gives the speaker and his companions a stage to prove their virile masculinity.33 This also occurs in Ulysses’ choice of the martial metaphor — the rusting sword that needs to ‘shine in use’ — to describe his own view about the dignity in old age. The poem concludes by simultaneously acknowledging the depredations of time and shrugging them off:

Tho’ much is taken, much abides; and tho’
We are not now that strength which in old days
Moved earth and heaven, that which we are, we are;
One equal temper of heroic hearts,
Made weak by time and fate, but strong in will
To strive, to seek, to find, and not to yield. (ll. 65–70)

The double insistence of ‘Tho’’ in line 65 suggests that Ulysses not only works against the cultural assumption that ageing is a process of decay, but also against his implicit internalization of the view. He convinces himself, through stubborn repetition of phrase and deed — ‘that which we are, we are’ — that much of the heroic ‘abides’ in the latter years of life. This view aligns with the vitalist tradition, which inspired numerous regimens designed to combat the decay associated with growing old. Sir Anthony Carlisle’s An Essay on the Disorders of Old Age (1818) devotes over one hundred pages to the proper diet for preserving vitality: ‘frequent and abundant supplies of renovating juices are more requisite in a vitiated condition of the ﬂuids, and where the maintenance of a due quantity of blood is precarious, both of which occur when the vital operations are enfeebled.’34 While vitalist theory constructed the lifespan as one of decay and depletion, it also enabled the view that — with proper hygiene — one could conserve the energy that sustained life and make the most of what ‘abides’. While ‘Ulysses’ is often read as a celebration of resilience against the ravages of time, its proud rhetoric belies a deeper recognition of the measures that must be taken to challenge encroaching decay.

Though similarly inspired by The Odyssey, ‘The Lotos-Eaters’ constructs an atmosphere of content at odds with the urgency espoused by Ulysses. Here, decay is not desired (as in ‘Tithonus’) or a provocation to action (as in ‘Ulysses’) but merely a natural process that has been shorn of its negative cultural connotations:

All things have rest, and ripen toward the grave
In silence — ripen, fall, and cease:
Give us long rest of death, dark death, or dreamful ease.35

The poem returns to the trope of decay to contrast with the weary work of toiling against fate:

The full-juiced apple, waxing over-mellow,
Drops in a silent autumn night.
All its allotted length of days
The flower ripens in its place,
Ripens and fades, and falls, and hath no toil,
Fast-rooted in the fruitful soil. (ll. 78–83)

The abjection of decay occurs within a utilitarian framework that values work over repose: humans devote immense amounts of energy to stave off decline, which could be better spent enjoying the pleasures of life. The rotting fruit represents matter’s happy unconsciousness of its place within this inevitable teleology. Decay is not something to reject, but a process on the same ontological plane as ripening — both processes occur within non-hierarchical allotments of time.36 In this ontologically neutral arrangement of time, the poem’s repeated assertion of stasis — ‘they came upon a land | In which it seemed always afternoon’, a ‘land where all things always seem’d the same!’ — does not exist in tension with the temporality of decay, but as an egalitarian levelling of different rhythms to the same value (ll. 3–4, 24). The loose structure of the choric song, which alternates between metrically irregular lines of tetrameter and pentameter, serves as the formal challenge to the sailor’s insistence that we find identity in difference.

‘The Lotos-Eaters’ asks the reader to cognitively detach decline from the normative values projected upon it by culture: in the realm of the poem decay and ripening exist on the same plane, different trajectories for equally necessary processes. This view of decay disentangles ageing from the fear of death and decline:

There is confusion worse than death.
Trouble on trouble, pain on pain,
Long labor unto aged breath,
Sore task to hearts worn out by many wars
And eyes grown dim with gazing on the pilot stars. (ll. 128–32, emphasis in original)

Old age makes legible the tally sheet of the long life: an interval when the accounting of pleasure and pain becomes most deeply embodied through ‘aged breath’, ‘hearts worn out’, and ‘eyes grown dim’. These markers reveal the cumulative damage done to a body over time. The tragedy of age, the ‘confusion worse than death’, arises from the wear and tear of rough work — the completion of which eventually renders one unable to do it any longer. Old age draws out the self-destroying logic of toil, as the abjection of being old derives from the shame of no longer being able to carry out work that slowly destroys the body. The ableist expectation of ‘Long labor’ constructs senescence as a zone of necessary failure that the lotos-eaters combat through the recognition of impermanence and change:

What is it that will last?
All things are taken from us, and become
Portions and parcels of the dreadful past. (ll. 90–92)

Read without irony, the poem’s call to irresponsibility provides an alternative to the encompassing capitalist ‘now’ of work and productivity. Francis O’Gorman connects the poem’s atmosphere of stasis with the political stultification leading up to the Reform Act of 1832: ‘What binds these together for the poet is a common problem of paralysis, a matter of reversal — and from the perspective of those outside Parliament — the persistent stalling of action.’37 It is in the interests of the dominant class to maintain the current milieu, to drag out the process of reform and make as few concessions as possible. In contrast to this eternally elaborated present of work, the lotos-eaters recognize that ‘Time driveth onward fast’; that the bodies within this industrial ‘now’ transform, wear out, and fail (l. 88). They become unrecognizable:

Dear is the memory of our wedded lives,
And dear the last embraces of our wives
And their warm tears: but all hath suffer’d change:
For surely now our household hearths are cold,
Our sons inherit us: our looks are strange:
And we should come like ghosts to trouble joy. (ll. 114–19)

The memory of the lotos-eaters becomes ‘dear’ in an economy of scarcity, where the sailors’ isolation prevents the creation of new memories. The recollection of ‘warm tears’ signifies a state of heightened feeling and fragmentation — of being torn apart by time and suffering ‘change’. The Oedipal anxiety about supplanting sons crystallizes in the belief that ‘our looks are strange’ — that their exile from the present corresponds to the ageing of their bodies beyond the hegemony of usefulness. Imagining themselves as ‘ghosts to trouble joy’, the sailors internalize the capitalist othering of older bodies as revolting, resigning themselves to an unchanging past along the margins of an ever-churning modernity.

## Conclusion

‘Tithonus’, ‘Ulysses’, and ‘The Lotos-Eaters’ find immense imaginative possibilities at the intersection of ageing and decay. For Tithonus, the horror of ageing into infinity has the effect of normalizing the experience of growing older. The poem provides a counterpoint to the desire to live ‘beyond the goal of ordinance’ — his youthful aversion towards decay and old age that leaves the ancient speaker unimaginably lonely at the end of the world. Ulysses’ rejection of the decline narrative belies the effects it has on the form of his monologue, provoking his urgency towards the ‘untravell’d world’ and the depredations of his anxious masculinity. While the lotos-eaters embrace the contentment that Ulysses rejects, they do so as a way of critiquing the capitalist system that grinds down the individuals it will marginalize once they are past prime working years. Each poem not only resists projecting stereotypes of physiological and social decline onto old age, but also makes the separation of these two systems — ageing and decay — central to the argument. They recuperate age from the overwhelmingly negative connotations associated with the processes of biological decay. Even when decay does not physically manifest itself in the human body, it serves as a figurative way of registering the abjectness of decline within patriarchal and capitalist frameworks of value. These institutions rely upon the stigma of decay as a way of constructing old age as the boundary of social inclusion, pathologizing traits that — though they are necessary and inevitable — do not reproduce the dominant milieu: vulnerability, dependence, idleness.

As his poems work to disable the connection between ageing and decay, they also imbue putrefaction with an ecological charge that goes against the grain of its cultural construction as revolting and abject. Tennyson wrote both ‘Ulysses’ and ‘Tithon’ in response to Hallam’s death, but both poems place decay in a more prominent position than mortality. Death implies a finality that the poet affectively and philosophically refuses to accept, preferring instead to imagine the transformation of the self into different forms. Early in In Memoriam the prospect of decay offers the poet some consolation of futurity as Hallam’s corpse mingles in the soil to create new matter:

’Tis well; ’tis something; we may stand
Where he in English earth is laid,
And from his ashes may be made
The violet of his native land.38

The concept of decay has a powerfully magnetic force in Tennyson’s poetry: centripetally drawing Tithonus inward, while centrifugally ejecting Ulysses into the wider world; drawing Hallam into the earth and expelling him as vegetable matter. Tennyson registers this force most powerfully through the form of his poetry, which wrinkles and withers to the melancholy rhythm of decay: a poetics that captures the hum and heat of a world in constant flux.

## Notes

1. ‘Tithonus’, in The Poems of Tennyson, ed. by Christopher Ricks, 2nd edn, 3 vols (Harlow: Longman, 1987), II, 605–12, l. 11. [^]
2. Martha C. Nussbaum and Saul Levmore, Aging Thoughtfully: Conversations About Retirement, Romance, Wrinkles, and Regret (Oxford: Oxford University Press, 2017), p. 114. [^]
3. Margaret Morganroth Gullette, Ending Ageism, Or How Not to Shoot Old People (New Brunswick: Rutgers University Press, 2017), p. 65. [^]
4. Hufeland’s Art of Prolonging Life, ed. by Erasmus Wilson, 2nd edn (London: Churchill, 1859), p. 23. [^]
5. James Copland, A Dictionary of Practical Medicine, 3 vols (London: Longman, Brown, Green, and Longmans, 1834), I, 46. [^]
6. P. M. Roget, ‘Age’, in The Cyclopædia of Practical Medicine, ed. by John Forbes, Alexander Tweedie, and John Conolly, 4 vols (London: Sherwood, 1833), I, 34–46 (pp. 35, 43). [^]
7. Even Thomas Andrews’s Cyclopedia of Domestic Medicine and Surgery (Glasgow: Blackie, 1842), which does not explicitly use the term decay, still deploys language that borrows heavily from the rhetoric of rot: ‘from the first periods of old age, and sometimes sooner, the organs become deteriorated; […] many of them entirely lose their action; others are absorbed, and disappear; […] finally, at the age of decrepitude, life is reduced to some remains of the vital, and a few deteriorated nutritive functions’ (pp. 137–38). [^]
8. Simone de Beauvoir, The Coming of Age, trans. by Patrick O’Brian (New York: Norton, 1996), p. 40. [^]
9. The progression of a human life from infancy to old age follows a biological pattern that is heavily mediated by social and cultural assumptions about the ageing body. Predictions about how the body will react at a certain chronological age inform medical treatment (e.g. whether one will see a specialist in pediatrics or geriatrics) and social milestones (such as minimum drinking age or the threshold for retirement). [^]
10. Jamie Lorimer, ‘Rot’, Environmental Humanities, 8 (2016), 235–39 (p. 236). [^]
11. Lucinda Cole, ‘Introduction: Putrefaction and the Ecologies of Life: Enter the Vulture’, Configurations, 25 (2017), 137–43 (p. 138). [^]
12. Joanna Radin, ‘Rot’, in The Multispecies Salon <http://www.multispecies-salon.org/rot/> [accessed 28 February 2021]. [^]
13. John MacNeill Miller, ‘Composing Decomposition: In Memoriam and the Ecocritical Undertaking’, Nineteenth-Century Contexts, 39 (2017), 383–98 (p. 384). [^]
14. Christopher Hamlin writes of decay’s tendency to messy metaphorical application, a slimy slippage between outside and inside: ‘the essence of the concept of zymotic disease was that disease was a spreading internal rot, that it came from an external rot, and that it could be transferred to others.’ See Christopher Hamlin, ‘Providence and Putrefaction: Victorian Sanitarians and the Natural Theology of Health and Disease’, Victorian Studies, 28 (1985), 381–411 (p. 386). [^]
15. Ella Mershon, ‘Ruskin’s Dust’, Victorian Studies, 58 (2016), 464–92 (p. 468). [^]
16. Reza Negarestani, ‘Undercover Softness: An Introduction to the Architecture and Politics of Decay’, Collapse, 6 (2010), 379–430 (p. 387). [^]
17. ‘Ulysses’, in Poems of Tennyson, ed. by Ricks, I, 613–20, l. 7. [^]
18. George C. Williams, ‘The Tithonus Error in Modern Gerontology’, Quarterly Review of Biology, 74 (1999), 405–15 (p. 405). [^]
19. ‘The Devil and the Lady’, in Poems of Tennyson, ed. by Ricks, I, 13–72, ll. 133–38. [^]
20. The allusion to Ecclesiastes 12. 5 — which describes old age as a time when ‘the grasshopper drags itself along and desire fails’ — connects the desiccation of the insect to the withering of desire, another major trope in ‘Tithonus’. [^]
21. This can take the form of offhand remarks to more direct assertions about the nature of Tithonus’s condition. Herbert Tucker references ‘the endless decay of his own mythical monologist from the “Tithon” of 1833’ (Tennyson and the Doom of Romanticism (Cambridge, MA: Harvard University Press, 1988), p. 242). Owen Boynton writes that ‘Tithonus does nothing, and has nothing to do, except to measure his rate of decay according to Aurora’s regular departures and returns’ (‘Tennyson and the Weight of the Pause’, Victorian Poetry, 53 (2015), 229–42 (p. 236)). [^]
22. Cornelia Pearsall, Tennyson’s Rapture: Transformation in the Victorian Dramatic Monologue (Oxford: Oxford University Press, 2008), pp. 242, 259. [^]
23. Michael E. Greene, ‘Tennyson’s “Gray Shadow, Once a Man”: Erotic Imagery and Dramatic Structure in “Tithonus”’, Victorian Poetry, 18 (1980), 293–300 (p. 294). [^]
24. ‘Memory’, in Poems of Tennyson, ed. by Ricks, I, 94–96, ll. 9–16. [^]
25. Tennyson’s later poems do not display the same inventiveness regarding the possibilities of old age. In ‘By an Evolutionist’ (in Poems of Tennyson, ed. by Ricks, III, 201–02), the speaker cries out against age: ‘What hast thou done for me, grim Old Age, save breaking my bones on the rack? | Would I had past in the morning that looks so bright from afar!’ (ll. 9–10). And venerable age replies: ‘Done for thee? Starved the wild beast that was linkt with thee eighty years back. | Less weight now for the ladder-of-heaven that hangs on a star’ (ll. 11–12). This poem posits old age as designed to prepare the individual for imminent death and salvation by mitigating the passions and desires of youth. [^]
26. ‘Remorse’, in Poems of Tennyson, ed. by Ricks, I, 98–100, ll. 1–2. [^]
27. Linda K. Hughes, ‘From “Tithon” to “Tithonus”: Tennyson as Mourner and Monologist’, Philological Quarterly, 58 (1979), 82–89 (p. 88), emphasis in original. [^]
28. ‘Tithon’, in Poems of Tennyson, ed. by Ricks, I, 620–22, ll. 41–44. [^]
29. According to Gregory Tate, ‘the bare simplicity of the phrase “if I be he” intensifies the impact of its claim that the physical and mental changes an individual undergoes over time might so alter identity that past and present selves become separate subjects requiring separate pronouns.’ See Gregory Tate, ‘Tennyson and the Embodied Mind’, Victorian Poetry, 47 (2009), 61–80 (p. 75). [^]
30. Geoffrey Ward, ‘Dying to Write: Maurice Blanchot and Tennyson’s “Tithonus”’, Critical Inquiry, 12 (1986), 672–87 (p. 681); and W. David Shaw, ‘Tennyson and Zeno: Three Infinites’, Victorian Poetry, 47 (2009), 81–99 (p. 92). [^]
31. Erich Auerbach, Mimesis: The Representation of Reality in Western Literature, trans. by Willard R. Trask (Princeton: Princeton University Press, 2003), p. 7. [^]
32. Andrea Charise, ‘Romanticism against Youth’, Essays in Romanticism, 20 (2013), 83–100 (p. 85). [^]
33. Lynne O’Brien argues that ‘war functions metaphorically’ in Tennyson’s poems as ‘the preserving agency for male autonomy by countering the intrusion of female domesticity into the male realm’. See Lynne B. O’Brien, ‘Male Heroism: Tennyson’s Divided View’, Victorian Poetry, 32 (1994), 171–82 (p. 171). [^]
34. Anthony Carlisle, An Essay on the Disorders of Old Age, 2nd edn (London: Longman, 1818), p. 63. [^]
35. ‘The Lotos-Eaters’, in Poems of Tennyson, ed. by Ricks, I, 467–77, ll. 96–98. [^]
36. The seductions of this decadent view of decay are reproduced by the taunting voice in ‘The Two Voices’: ‘Why, if man rot in dreamless ease, | Should that plain fact, as taught by these, | Not make him sure that he shall cease?’ (Poems of Tennyson, ed. by Ricks, I, 569–93, ll. 280–82). [^]
37. Francis O’Gorman, ‘Tennyson’s “The Lotos-Eaters” and the Politics of the 1830s’, Victorian Review, 30.1 (2004), 1–20 (p. 5). [^]
38. ‘In Memoriam’, in Poems of Tennyson, ed. by Ricks, II, 304–459, 18. 1–4. [^]


text:
# Is Conditional Generative Modeling all you need for Decision-Making?

1 Improbable AI Lab 2 MIT

*indicates equal contribution.
arXiv 2022

## Abstract

Recent improvements in conditional generative modeling have made it possible to generate high-quality images from language descriptions alone. We investigate whether these methods can directly address the problem of sequential decision-making. We view decision-making not through the lens of reinforcement learning (RL), but rather through conditional generative modeling. To our surprise, we find that our formulation leads to policies that can outperform existing offline RL approaches across standard benchmarks. By modeling a policy as a return-conditional diffusion model, we illustrate how we may circumvent the need for dynamic programming and subsequently eliminate many of the complexities that come with traditional offline RL. We further demonstrate the advantages of modeling policies as conditional diffusion models by considering two other conditioning variables: constraints and skills. Conditioning on a single constraint or skill during training leads to behaviors at test-time that can satisfy several constraints together or demonstrate a composition of skills. Our results illustrate that conditional generative modeling is a powerful tool for decision-making.

## Constraint Satisfaction

Combining Stacking Constraints

Combining Rearrangement Constraints

'NOT' constraints in Stacking and Rearrangement

Infeasible constraints lead to incoherent behavior

## Skill Composition

Naive Skill Composition via sum of conditioning variables

Anurag Ajay

MIT

Yilun Du

MIT

Abhi Gupta

MIT

Joshua Tenenbaum

MIT

Tommi Jaakkola

MIT

Pulkit Agrawal

MIT

## Bibtex

@article{ajay2022conditional,
title={Is Conditional Generative Modeling all you need for Decision-Making?},
author={Ajay, Anurag and Du, Yilun and Gupta, Abhi and Tenenbaum, Joshua and Jaakkola, Tommi and Agrawal, Pulkit},
journal={arXiv preprint arXiv:2211.15657},
year={2022}
}

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# Combinatorics problem?

## Recommended Posts

Okay here's the problem: I have a cube and 6 panels. The user has to paste these panels in the right cube faces(lets call them faces) to make a picture. The panels can go anywhere, as long as the final result is rotationally congruent to the solution. Also, the panels should be rotatable over the faces. So basically there's more than 1 panel-face set solution. So I can stick these panels to the box and get the user solution. So there's a 1:1 panel-face correspandence, plus the panel orientation (rotation over the face). My problem is how to check if the solution is correct. I don't know to go about this. What topic covers this problem? Graph theory? Combinatorics? Specifically? Thanks for your guidance. Edit: okay came up with a function but there seems to be some problems. First the code:
/*------------------------------------------*
Top, right, bot, left
Basically this means that the face to the left of face 1 is boxSolution[1][3]... etc
Visually, panel 0 is facing away from the camera,
1 is the left side, 2 is the front, 3 is the right,
4 is top, and 5 is bottom.
The side panels are oriented as top being the positive y-axis,
while panel 4's top is away from the camera, and 5's is towards the camera.

/*------------------------------------------*/
int boxSolution[6][4] =
{
{4,1,5,3},
{4,2,5,0},
{4,3,5,1},
{4,0,5,2},
{0,3,2,1},
{2,3,0,1}
};

/*-------------------------------------------------------*
CheckSolution
Evaluates the solution and returns true if correct
/*-------------------------------------------------------*/
bool Game::CheckSolution()
{
//for each panel
for(u32 i = 0; i < 6; i++)
{
//check neighbors

//for each neighbor
for(u32 j = 0; j < 4; j++)
{
int neighbor = ((int)j+vecPanel[i]->orientation) % 4;
//orientation here is clockwise rotation over the face.
//This line is since if I rotate the panel,
//the panels adjacent to it have to change indices.

int fIndex = boxSolution[vecPanel[i]->intAttachedFace][neighbor];
// the neighboring face index
if(
puzzleBox->face[fIndex].attachedPanel->index
//top face panel, the actual panel
!= boxSolution[i][j] )
//correct panel, panel that should be there
{
return false;
}

}
}
return true;
}

Hope the variables are descriptive enough to understand. Anyway, the function returns true when I put panel 0 on face 0, 1 on 1 and so on. But the moment I put panel 0 somewhere else, (rotating the panels as I go, making it rotationally congruent) and so on, it returns false. Anyone care to help? [Edited by - kenjinsakura on February 23, 2010 1:43:35 AM]

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The branch of Mahematics that deals with this type of problem is called Group Theory. Or at least it deals with similar types of problems involving symmetry.

I can't think of an elegant solution to your problem right now, but I'll think about it.

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I think I figured it out. I don't understand how you are encoding the current position, so I'll describe a possible solution assuming a different description. Let's say an array int location[6]' tells me where each panel ended up. I'll mark an edge of each panel and indicate the rotation of the panel by saying which neighbor it points to: This will be stored in int pointing_to[6]'.

Say my canonical solution is this:
Panel 0 is at face 0, pointing to 4.
Panel 1 is at face 1, pointing to 4.
Panel 2 is at face 2, pointing to 4.
Panel 3 is at face 3, pointing to 4.
Panel 4 is at face 4, pointing to 0.
Panel 5 is at face 5, pointing to 0.

Try this:
#include <iostream>enum Face {  Face_back, Face_left, Face_front, Face_right, Face_top, Face_bottom};struct Position {  int location[6]; // where each panel ended up  int pointing_to[6]; // where each panel is pointing to};Position canonical_solution={{0,1,2,3,4,5},{4,4,4,4,0,0}};bool is_solution(Position const &position) {  for (int i=0; i<6; ++i) {    if (position.pointing_to[i]        != position.location[canonical_solution.pointing_to[i]])      return false;  }  return true;}int main() {  Position position={{1,2,3,0,4,5},{4,4,4,4,1,1}};  std::cout << is_solution(position) << '\n';}

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It sounds like a typical graph theory problem to me. Call the faces 1,2,3,4,5,6 and imagine they're laid out like this:

   51  2  3  4   6

If we were to fold this back up into a cube and put face 2 on the table (so that face 4 is facing up to the sky), you could create a graph. Each node would have exactly 4 edges, pointing to the other faces that were adjacent. In addition, they should be named edges so that you maintain the consistent structure of the cube. i.e. name the edges north, south, east, west or something.

Furthermore, each node has an image with a rotation factor.

When you apply any transformation to the cube, all that happens is a) you're changing which edges point north, east, west, etc. and b) you're rotating the image 90 degrees around some axis.

So the problem is a simple search from a starting configuration to an ending configuration, where the possible operations are rotating the cube 90 degrees about the x, y, or z axis. This is a very small search space, so should be easy to solve.

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Think of it this way... First, physically, as though you'd built this thing out of wood or something:

- Assemble a reference cube which is correct.
- Paint each cube edge a different color (so that color gets on an edge of both tiles sharing that cube edge) and let the paint dry.
- Disassemble the cube.

Now, reassemble the cube however you want. It is correct if and only if the colors agree on all the cube edges.

Now: How would you code this? I'd use a "map" data structure (e.g., the one provided by the STL). Basically, you have a map, initially empty, from colors to cube edges. Now, one tile at a time, start adding the (color,cube_edge) key-value pairs to the map. If you ever overwrite an existing key with a different value, you know your cube isn't right. If you get through adding all the colors to your map without this occurring, then your cube is good.

On second thought, use a simple 1-1 hash instead of a map (i.e., an array that takes color ids as indices, and stores edge ids; it'd be initialized to all "no edge yet.") The same principle applies though.

[Edited by - Emergent on February 23, 2010 4:18:03 PM]

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Quote:
 Original post by alvaroI think I figured it out. I don't understand how you are encoding the current position, so I'll describe a possible solution assuming a different description. Let's say an array int location[6]' tells me where each panel ended up. I'll mark an edge of each panel and indicate the rotation of the panel by saying which neighbor it points to: This will be stored in int pointing_to[6]'.Say my canonical solution is this:Panel 0 is at face 0, pointing to 4.Panel 1 is at face 1, pointing to 4.Panel 2 is at face 2, pointing to 4.Panel 3 is at face 3, pointing to 4.Panel 4 is at face 4, pointing to 0.Panel 5 is at face 5, pointing to 0.Try this:*** Source Snippet Removed ***

I got it. My problem was I was rotating the panels counter-clockwise instead of clockwise, so visually, it would be correct, but the data wouldn't. I think we basically came up with similar algorithms, although I had to have the complete face adjacency list encoded because I had no way of knowing where each panel was "pointing" to unless i knew its orientation, position and the face adjacency list. Complicated data structures T_T

Although, you're right, I didn't have to check all the neighbors of each panel, just 1 for each would suffice, so I took out 1 loop right there.

Thanks for the help.

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# What is the indicated real rrot?

• What is the indicated real rrot?

What is the indicated real rrot? More questions about Family & Relationships, what. Ask Drum Tom. ... Find the indicated real nth root(s) of a. a. n ...
Positive: 88 %
Positive: 85 %

### More resources

Principal Nth Root Calculator, Free , ... Real World Math Horror Stories from Real encounters Math Riddles Advertisement . Contact; Site Map; TOS
Positive: 88 %
Wolfram Data Framework Semantic framework for real-world ... > Working with the Notebook Interface > Two-Dimensional Expression Input > Typing Square Roots.
Positive: 83 %
The characteristics of square root function can be stated as: ... = $\sqrt{x}$ is set of all non negative real numbers, i.e f(x) $\geq$ 0.


text:
# 49th SLAC Summer Institute (SSI 2021)

16-27 August 2021
SLAC
America/Los_Angeles timezone

## Directly Probing the Higgs-top Coupling at High Scales

Not scheduled
20m
ZOOM videoconf (SLAC)

### Speaker

Roshan Mammen Abraham (Oklahoma State University)

### Description

The top-quark Yukawa coupling $y_t$ is the strongest interaction of the Higgs boson in the Standard Model (SM) with $y_t \sim 1$. Due to its magnitude, it plays a central role in Higgs phenomenology in the SM and would be most sensitive to physics beyond the Standard Model. The top Yukawa can be directly measured at the LHC via top pair production in association with a Higgs boson  $t\bar{t}h$. We study new physics effects for the Higgs-top coupling at high scales, using jet substructure techniques. We present the high-luminosity LHC sensitivity to new physics parametrized in the EFT framework and through a general Higgs-top form factor.

### Primary authors

Roshan Mammen Abraham (Oklahoma State University) Dorival Goncalves (Oklahoma State University) Tao Han (University of Pittsburgh) Sze Ching Iris Leung (University of Pittsburgh) Han Qin (University of Pittsburgh)

### Presentation Materials

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text:
# Quotients and Homomorphisms for Beginners: Part 3, Nomenclature and the Integers Modulo n

The last post culminated in the definition of the quotient group. We saw that this group is constructed by essentially “dividing” the group into cosets and working with those. This is one of the reasons we deem the group the quotient group. One should note, however, that some authors use the alternative terminology factor group, e.g. Lang’s famous Algebra uses the term, but it is worth noting that he often uses odd conventions, for instance he introduces but never names the “Isomorphism theorems.”

There is another reason for the name “quotient,” which is probably where the term comes from in the first place. Before explaining the name, however, we should introduce the quintessential example of a quotient group: the integers modulo $n$. When working in general algebra, the integers are almost always the example we care about, because algebra was developed in no small part to do number theory. Let us quickly prove a theorem about the group of the integers under addition before proceeding.

Theorem. The subgroups of $(\mathbb{Z}, +)$ are of the form $n\mathbb{Z}$ for $n$ an integer.

Proof. We will only prove that the subsets of that form are indeed subgroups. The proof that these are the only such subgroups will be left as an exercise (Hint: recall the Euclidean algorithm).

First, we show closure under addition. If $nx, ny \in n\mathbb{Z}$, then $nx+ny=n(x+y)$, which is in $n\mathbb{Z}$. Clearly, the identity is $0= (0)n \in n\mathbb{Z}$, and the inverse of $n x$ is $-nx=n(-x) \in n\mathbb{Z}$. $\blacksquare$

It is easy to see that the subgroups $n\mathbf{Z}$ are normal, because the subgroups are more than that: they are abelian. Therefore, we have the quotient group $\mathbf{Z} / n\mathbf{Z}$ also known as the integers mod $n$ and sometimes denoted $\mathbf{Z}_n$ (not to be confused with the $n$-adic numbers). In my opinion, it is actually a little weird to see how this group fits in with quotient groups in general. Understanding the group is easy, but the notation and how we can figure out what it is just based on the general definition of $G/H$ was not instant for me when I was first introduced to the subject. So, I will take a bit of care to show how the two coincide, in case I am not the only person susceptible to this little struggle. Either way, it will take some effort to truly internalize all of this.

Generally, we say $\mathbf{Z}/n\mathbf{Z} := \{0, \ldots n-1 \}$ with addition mod $n$, but this is a bit misleading. Let us start from the beginning. The subgroup is $n \mathbf{Z}=\{ 0 , \pm n , \pm 2n , \ldots \}$, and so the cosets are

$0+n\mathbf{Z} , 1+n\mathbf{Z}, \ldots , (n-1)+n\mathbf{Z}$

We claim that these are all the cosets, because if $k \in \mathbf{Z}$, then

$k=nq+r \; , \; 0 \leq r < n \implies k+n\mathbf{Z}=nq+n\mathbf{Z}+r= n \mathbf{Z} + r$

But, this is already in the list, because of the restriction on $r$. $\blacksquare$

So, for simplicity we generally identify coset $m + n\mathbf{Z}$ with $m$.

And, so we can compute the Cayley table (multiplication table) for small values of $n$ quite easily. Below is the Cayley table for $Z/4Z$.

We can now see where the integers come in the naming of this group. When one divides, for instance, 15 by 5, one obtaains 3 because one can regroup 15 objects into 3 groups (in the colloquial sense) of 5 objects. In the quotient group, we have the same thing but with additional structure, namely the group structure of the integers.

Next time, we will digress a bit before continuing with the theory of quotient groups. Eventually, we will make our way to the isomorphism theorems and more.


text:
Resistor selected for Low-Side Sensing

I’m planning low-side sensing with the Allegro Two-Wire Hall-Effect Switch (A1190LUBTN-T) and I’d like to confirm my resistor selection for Rsense.

Current is 2-17mA and my ADC range is 0-3.3V.

V=I*R: 3.3V = (.017A) * (Rsense) gives Rsense = 194 ohms.

P=I*V: P = (.017 A) * (3.3 V) = .056 W

So, this 220 ohm 1/8 watt SIP-11 resistor array 4611X-101-221LF should be just about perfect?

Thanks!

• 200$\Omega$*17mA=3.74V, which is out of the ADC range. If you're just trying to detect the switch position, you can use a comparator instead of the ADC. – vofa Jan 22 '18 at 18:29
• @vofa -- (sorry i didn't mention upfront) I am just detecting switch position, so I don't need the entire dynamic range. I also need to use ADC on the Espressif ESP32 and not dissipate excess power on Rsense. Will that help specify a solution? – robg Jan 22 '18 at 19:39


text:
#### LaTeX Beamer

How can I avoid the navigation symbols at the right lower corner in
the pdf output?

Ulrich

 0
ugroh (21)
6/18/2010 11:07:52 AM
comp.text.tex 37519 articles. 0 followers.

4 Replies
588 Views

Similar Articles

[PageSpeed] 25
Le vendredi 18/06/10 =E0 04h07,
Ulrich <ugroh@mac.com> a =E9crit :

> How can I avoid the navigation symbols at the right lower corner in
> the pdf output?

--=20
Denis

 0
Denis
6/18/2010 11:11:52 AM
In article <20100618131152.02218ab9@drums>, dbitouze.no@spam.wanadoo.fr
says...
>
> Le vendredi 18/06/10 � 04h07,
> Ulrich <ugroh@mac.com> a �crit :
>
> > How can I avoid the navigation symbols at the right lower corner in
> > the pdf output?
>

 0
Dr
6/18/2010 12:28:46 PM
Le vendredi 18/06/10 =E0 08h28,
Dr Engelbert Buxbaum <engelbert_buxbaum@hotmail.com> a =E9crit :

Where is it documented?
--=20
Denis

 0
Denis
6/18/2010 12:33:11 PM
Denis Bitouzé <dbitouze.no@spam.wanadoo.fr> writes:

> Le vendredi 18/06/10 à 08h28,
> Dr Engelbert Buxbaum <engelbert_buxbaum@hotmail.com> a écrit :
>
>
> Where is it documented?

Line 422 of beamerbasecompatibility.sty is:

The file name suggests that this is only included for compatibility
reasons and should not be used.

--
Change “LookInSig” to “tcalveu” to answer by mail.

 0
Philipp
6/18/2010 7:51:08 PM
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text:
## LESSWRONGLW

So when we talk about the dharma or justify our actions on it, it's worth noting that it is not really trying to provide consistent episteme. [...] Thus it's a strange inversion to ask the dharma for episteme-based proofs. It can't give them, nor does it try, because its episteme is not consistent and cannot be because it chooses completeness instead.

In my view, this seems like a clear failing. The fact that the dharma comes from a tradition where this has usually been the case is not an excuse for not trying to fix it.

Yes, the method re... (read more)


text:
# Product of hausdorff spaces

1. Sep 26, 2010

### emptyboat

Hello, everyone.

Theorem) If each space Xa(a∈A) is a Hausdorff space, then X=∏Xa is a Hausdorff space in both the box and product topologies.

I understand if a box topology, the theorem holds.
but if a product toplogy, I do not understand clearly.

I think if there are distinct points c,d in X, then Uc, Ud (arbitrary open sets in X contain c, d respectively) are equals Xa except for finitely many values of a, so Uc and Ud are not disjoint.
If I have a mistake, please point out it....

2. Sep 27, 2010

Start with this: if c and d are different points of X then there is an index $$a\in A$$ for which the projections of c and d differ. Exploit this value of the index.


text:
Pairs Satisfying a Cubic

$$n$$ and $$m$$ are positive integers that satisfy $$n^3 + 2n^2 = m^2$$. If $$1 \leq n \leq 1000$$, how many possible ordered pairs of $$(n,m)$$ are there?

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## Computational Methods for Bayesian Model Choice

Posted in Statistics, University life with tags , , on February 26, 2009 by xi'an

Next Monday, I am starting a series of four (advanced graduate) lectures about computational methods for Bayesian model choice that tries to summarise what we know about Bayes factors and evidence from a computational viewpoint. This is therefore quite related with the seminar I gave in Montréal

and the seminar I gave in Montpellier

The textbook I use as support is Chen, Shao and Ibrahim’s Monte Carlo Methods in Bayesian Computation because it is more focussed on this specific issue than Monte Carlo Statistical Methods or Bayesian Core. The courses will take place at CREST-ENSAE, Monday 3 from 11am to 1pm, Thursday 5 from 10am till 1pm, Monday 9 from 10am till 1pm and Thursday 12 from 11am till 1pm.

## Good size swans and turkeys

Posted in Books, Statistics with tags , , , , on February 24, 2009 by xi'an

In connection with The Black Swan, Nassim Taleb wrote a small essay called The Fourth Quadrant on The Edge. I found it much more pleasant to read than the book because (a) it directly focus on the difficulty of dealing with fat tail distributions and the prediction of extreme events, and (b) it is delivered in a much more serene tone than the book (imagine, just the single remark about the Frenchs!). The text contains insights on loss functions and inverse problems which, even though they are a bit vague, do mostly make sense. As for The Black Swan, I deplore (a) the underlying determinism of the author, which still seems to believe in an unknown (and possibly unachievable) model that would rule the phenomenon under study and (b) the lack of temporal perspective and of the possibility of modelling jumps as changepoints, i.e. model shifts. Time series have no reason to be stationary, the less so the more they depend on all kinds of exogeneous factors. I actually agree with Taleb that, if there is no information about the form of the tails of the distribution corresponding to the phenomenon under study—assuming there does exist a distribution—, estimating the shape of this tail from the raw data is impossible.

The essay is followed by a technical appendix that expands on fat tails, but not so deeply as to be extremely interesting. A surprising side note is that Taleb seems to associate stochastic volatility with mixtures of Gaussians. In my personal book of models, stochastic volatility is a noisy observation of the exponential of a random walk, something like$\nu_t={\exp(ax_{t-1}+b\epsilon_t)},$thus with much higher variation (and possibly no moments). To state that Student’s t distributions are more variable than stochastic volatility models is therefore unusual… There is also an analysis over a bizillion datasets of the insanity of computing kurtosis when the underlying distribution may not have even a second moment. I could not agree more: trying to summarise fat tail distributions by their four first moments does not make sense, even though it may sell well. The last part of the appendix shows the equal lack of stability of estimates of the tail index${\alpha},$which again is not a surprising phenomenon: if the tail bound K is too low, it may be that the power law has not yet quicked in while, if it is too large, then we always end up with not enough data. The picture shows how the estimate widely varies with K around its theoretical value for the log-normal and three Pareto distributions, based on a million simulations. (And this is under the same assumption of stationarity as above.) So I am not sure what the message is there. (As an aside, there seems to be a mistake in the tail expectation: it should be

$\dfrac{\int_K^\infty x x^{-\alpha} dx}{\int_K^\infty x^{-\alpha} dx} = \dfrac{K(\alpha-1)}{(\alpha-2)}$

if the density decreases in$\alpha\cdots$It is correct when$\alpha$is the tail power of the cdf.)

Posted in Books, Kids with tags , , on February 23, 2009 by xi'an

Over the past weekend, I watched Blade Runner with my kids, as I was forced to inactivity by the demise of my mailbox! I had not watched the movie for twenty years, since the time I was a postdoc at Cornell and enjoying the student movie club, so it was almost like watching Blade Runner for the first time. (In particular, except for the cut of the final scene, I could not spot changes from the 1977 version.)

The atmosphere of the movie has not changed, though, in its oppressiveness. The play on lights is a major factor for this feeling with no natural light ever used but instead side glares that enter buildings periodically, including the apartment of the detective, Deckard (which makes it appear less private, in a Big Brother kind of way), or wax candles for the magnate Tyrell. The sci-fi touch is somewhat light, except for the obligatory flying cars (in 2019?!), which is just as good because this does not age well (like, the computer screens already appear antiquated or the phones are fixed phones, not cell phones). The themes are highly reminiscent of Philip K. Dick‘s universe, with an asianised LA, including origamis (just as in The Man in the High Castle), a permanent ambiguity/paranoia about the status/feeling of the characters (it is never clear in the movie that Deckard is not a replicant), the dubious nature of humanity, and a pessimistic view of the future civilisations. I did not remember, though, the strong connections with the films noirs of the 50’s, from the light—and the omnipresent cigarette smoke diffracting this light—to the costumes, and obviously to the hard-boiled attitude of Deckard. Even though I found the interpretation of Harrisson Ford somehow missing in depth (but this may be part of the ambiguity about his true nature, human versus replicant), I still agree with my former impression of Blade Runner being truly a cult film. (Unsurprisingly, my kids found the movie terrible, if only for the “poor” special effects!)

## Model choice by Kullback projection (2)

Posted in Statistics with tags , , , , on February 20, 2009 by xi'an

Yesterday I talked about the paper of Nott and Cheng at the Bayesian model choice group and [with the help of the group] realised that my earlier comment on the paper

There is however one point with which I disagree, namely that the predictive on the submodel is obtained in the current paper by projecting a Monte Carlo or an MCMC sample from the predictive on the full model, while I think this is incorrect because the likelihood is then computed using the parameter for the full model. Using a projection of such a sample means at least reweighting by the ratio of the likelihoods…

was not completely accurate. The point is [I think] correct when considering the posterior distribution of the projected parameters. Thus, using a projection of an MCMC sample corresponing to the full model will not result in a sample from the posterior distribution of the projected parameters. On the other hand, projecting the MCMC sample in order to get the Kullback-Leibler distance posterior distribution as done in the applications of Section 7 of the paper is completely kosher, since this is a quantity that only depends on the full model parameters. Since Nott and Cheng do not consider the projected model at any time (even though Section 3 is slightly unclear, using a posterior on the projected parameter), there is nothing wrong in their paper and I do find quite interesting the idea that the lasso penalty allows for a simultaneous exploration of the most likely submodels without a recourse to a more advanced technique like reversible jump. (The comparison is obviously biased as the method does not provide a true posterior on the most likely submodels, only an approximation of their probability. Simulating from the constrained projected posterior would require extra steps.)

## ABC methods for model choice in Gibbs random fields

Posted in Statistics with tags , , , , , , on February 19, 2009 by xi'an

We have resubmitted to Bayesian Analysis a revised version of our paper ” ABC methods for model choice in Gibbs random fields” available on arXiv. The only major change is the addition of a second protein example in the biophysical illustration. The core idea in this paper is that, for Gibbs random fields and in particular for Ising models, when comparing several neighbourhood structures, the computation of the posterior probabilities of the models/structures under competition can be operated by likelihood-free simulation techniques akin to the Approximate Bayesian Computation (ABC) algorithm often discussed here. The point for this resolution is that, due to the specific structure of Gibbs random field distributions, there exists a sufficient statistic across models which allows for an exact (rather than Approximate) simulation from the posterior probabilities of the models. Obviously, when the structures grow more complex, it becomes necessary to introduce a true ABC step with a tolerance threshold$\mathbf{\epsilon}$in order to avoid running the algorithm for too long. Our toy example shows that the accuracy of the approximation of the Bayes factor can be greatly improved by resorting to the original ABC approach, since it allows for the inclusion of many more simulations. In the biophysical application to the choice of a folding structure for two proteins, we also demonstrate that we can implement the ABC solution on realistic datasets and, in the examples processed there, that the Bayes factors allow for a ranking more standard methods (FROST, TM-score) do not.

## Just another strike?

Posted in University life on February 18, 2009 by xi'an

As noted on a previous post, most French universities are currently facing strike actions. While it may sound from abroad like nothing unusual, France being famous for its Spring strikes…, this protest runs much deeper than usual strikes. It was started by a greater-autonomy project from the (French) government to delegate pay rises, promotions and teaching duties to university presidents, rather than the present use of a national standard for teaching loads and of a national committee for research evaluation and promotions. This may sound weird to US and UK academics, for whom local bargaining is the rule, but most French academics fear that the complete delegation of those powers to the sole president of their university without any counter-power will leave them unprotected, because of the small size of most universities and of the danger of nepotism and of field bias. (The presidents of French universities being elected from the faculty, they are necessarily from one field…) While I do not think strikes or demonstrations are of much use, and that an increased autonomy of our universities is a good think, I tend to agree with this analysis that university presidents suddenly got much too much power in their hand with no independent body to balance this power. The proposed changes are both too narrow (no autonomy for degrees, fees, salaries) and too broad (reduced budgets for more expenses and less positions for more duties on both administrators and faculty). Being imposed from the top in a traditional French way does not either make them more palatable nor intelligible to the community.

An aggravating factor in this crisis is a speech given by President Sarkozy on January 22 and discussed here in Nature. The tone of this speech was so scathingly dismissive of researchers and of their “petty conservatism” and so misrepresentative of a complex reality that it set most of the academic community against the speaker and obviously against the on-going project…. The most recent French Field medalist, Wendelin Werner, just published an open letter to the President in Le Monde that, given its moderate and non-agressive tone, shows how deep a drift President Sarkozy’s speech has induced between his government and the researchers’ community. I am afraid that the withdrawal of the current project will not, by itself, suffice to reconcile the community.

## The R Companion to MCSM (6)

Posted in Books, Statistics with tags , , , on February 17, 2009 by xi'an

The chapter on the Metropolis algorithm is now completed and we are thus tantalisingly close to the end! (The end of the complete draft…) The completed chapters are

1. Introduction to R programming
2. Random variable generation
3. Monte Carlo methods
4. Controlling and accelerating convergence
5. Monte Carlo optimization
6. Metropolis-Hastings algorithms
7. [=8] Convergence monitoring for MCMC algorithms

We have now reached 226 pages, 72K words (whatever that means using wc on a pdf file), and 69 figures… There still seems to be a possibility that the final chapter on Gibbs sampling could be ready by the end of the month, if both George and I make rush for it. There is no major surprise in the current chapter, with independent Metropolis and random walk Metropolis algorithms being the central heroes, but there still was work to be done, in terms of coding new examples. We also included a nice Bayesian model choice illustration inspired from Bayesian Core where the Metropolis-Hastings algorithm only moves over model indices, the parameters being analytically integrated out. Once the first draft is over, the next stepstone will be the design of the corresponding package, collecting and classifying our R codes and few datasets…

PS—The title preferred by those who voted on the poll seems to be Monte Carlo Methods with R.