45626993
Computable Boolean Algebras
Feiner [F] showed that a Boolean algebra need not have a computable copy (see also [T 2 ]). Downey and Jockusch [D-J] showed that every low Boolean algebra does have a computable copy. Thurber [T 3 ], showed that every low 2 Boolean algebra has a computable copy. Here we show that every Boolean algebra which is low 3 , or even low 4 , has a computable copy. The results of [D-J] and [T 3 ] were obtained by passing to linear orderings. In [D-J], there is an embedding theorem saying that any linear ordering which is with the successor relation as an added predicate can be embedded in a slightly larger linear ordering which is computable. An isomorphism theorem of Remmel [R] is used to show that the interval algebras of the two linear orderings are isomorphic (except in a trivial case). In [T3], there is an embedding theorem saying that any linear ordering which is with certain added predicates can be embedded in one which is with successor. Again the isomorphism theorem of Remmel is used to show that the interval algebras are isomorphic (except in a trivial case). Here, instead of passing to linear orderings, we work directly with Boolean algebras. We begin with a review of the known results. We re-formulate the embedding theorems of Downey-Jockusch and Thurber in terms of Boolean algebras. We extract from Remmel's isomorphism theorem some information on complexity. In this way, we show that a low Boolean algebra is isomorphic to a computable one by an isomorphism which is , at worst, and the same is true for a low 2 Boolean algebra.
4785970
Sequences of n-Diagrams
We consider only computable languages, and countable structures, with universe a subset of ω, which we think of as a set of constants. We identify sentences with their Gödel numbers. Thus, for a structure A, the complete (elementary) diagram, Dc(A), and the atomic diagram, D(A), are subsets of ω. We classify formulas as usual. A formula is both Σ0 and Π0 if it is open. For n > 0, a formula, in prenex normal form, is Σn, or Πn, if it has n blocks of like quantifiers, beginning with ∃, or ∀. For a formula θ, in prenex normal form, we let neg(θ) denote the dual formula that is logically equivalent to ¬θ–if θ is Σn, then neg(θ) is Πn, and vice versa.
14175074
Approximate regular expression pattern matching with concave gap penalties
Given a sequenceA of lengthM and a regular expressionR of lengthP, an approximate regular expression pattern-matching algorithm computes the score of the optimal alignment betweenA and one of the sequencesB exactly matched byR. An alignment between sequencesA=a1a2 ... aM andB=b1b2... bN is a list of ordered pairs, 〈(i1,j1), (i2j2), ..., (it,jtt)〉 such that ik < ik+1 and jk < jk+1. In this case the alignmentaligns symbols aik and bjk, and leaves blocks of unaligned symbols, orgaps, between them. A scoring schemeS associates costs for each aligned symbol pair and each gap. The alignment's score is the sum of the associated costs, and an optimal alignment is one of minimal score. There are a variety of schemes for scoring alignments. In a concave gap penalty scoring schemeS={δ, w}, a function δ(a, b) gives the score of each aligned pair of symbolsa andb, and aconcave function w(k) gives the score of a gap of lengthk. A function w is concave if and only if it has the property that, for allk > 1, w(k + 1) −w(k) ≤w(k) −w(k −1). In this paper we present an O(MP(logM + log2P)) algorithm for approximate regular expression matching for an arbitraryδ and any concavew.
13577137
The comfort assessment of wearable computers
This paper presents a tool to measure the comfort of wearable computers. The comfort rating scales (CRS) measure wearable comfort across 6 dimensions. These dimensions are Emotion, Attachment, Harm, Perceived change, Movement and Anxiety. This paper also presents two studies in which the CRS have been used to assess the comfort of two types of wearable technology currently being developed at the University of Birmingham, these are the SensVest and the /spl chi//sup 3/. The results of the studies show that the CRS can be used to aid designers and manufacturers focus on what modifications are needed to wearable computer design to make them more comfortable. They also show that assessments of wearable computer comfort must be made in situations and environments to which the computer will ultimately be introduced.
1439790
Physical resource binding for a coarse-grain reconfigurable array using evolutionary algorithms
One of the challenges of designing for coarse-grain reconfigurable arrays is the need for mature tools. This is especially important because of the heterogeneity of the larger, more predefined (and hence more specialized) array elements. This work describes the use of a genetic algorithm (GA) to automate the physical binding phase of kernel design. We identify the generalizable features of an example platform and discuss suitable ways to harness the binding problem to a GA search engine.
34030883
Operations research in the high-level synthesis of integrated circuits
Abstract The acceptance of high-level synthesis tools and methodologies by the design engineers depends on their efficiency in producing circuits with small silicon areas and high operating speeds. This paper shows how this efficiency can be achieved through the use of several operations research techniques applied to the many optimization problems that must be solved. These include: shortest path algorithms, integer programming techniques applied to silicon area minimization, force directed scheduling to optimize the number of operators and cost/speed trade-offs of logical gates. This paper presents several examples providing an operations research solution to each of them.
8846958
Wearable computers and the possible development of musculoskeletal disorders
Work-related musculoskeletal disorders (WRMDs) have been shown to be caused by (amongst other things) exposure to work tasks which involve constrained pathomechanical body postures and physical load. Current research suggests that the added weight of a wearable computer and the positions which interacting with it requires, induces acute musculoskeletal stress and may lead to chronic musculoskeletal disorders. These disorders may only reveal themselves after a long period of time. Therefore it is important at this stage in wearable computer development to address these issues in the hope of diminishing their occurrence.