Y. Sergeyev developed a positional system for representing infinite numbers using a basic unit called a "grossone", as well as what he calls an "infinity computer". The mathematical value of this seems dubious but numerous articles have already appeared in refereed *research* journals. Thus, there are currently 23 such articles in [mathscinet](http://www.ams.org/mathscinet/search/publications.html?pg4=AUCN&s4=sergeyev&co4=AND&pg5=TI&s5=&co5=AND&pg6=JOUR&s6=&co6=AND&pg7=ALLF&s7=infinit*&co7=AND&dr=all&yrop=eq&arg3=&yearRangeFirst=&yearRangeSecond=&pg8=ET&s8=All&review_format=html&Submit=Search) not to speak of numerous lectures in conferences.


In a comment accessible [here](http://link.springer.com/article/10.1007/s00283-015-9600-7) Sergeyev asserts that "Levi-Civita numbers are built using a generic infinitesimal $\varepsilon$ ... whereas our numerical computations with finite quantities are concrete and not generic." Here apparently "finite" is a misprint and should be "infinite". How is this comment on the difference between Sergeyev's grossone one the one hand, and the Levi-Civita unit on the other, to be understood?


In a 2013 article, Sergeyev compares his grossone to Levi-Civita in the following terms in footnote 5: *5 At the first glance the numerals (7) can remind numbers from the Levi-Civita field (see [20]) that is a very interesting and important precedent of algebraic manipulations with infinities and infinitesimals. However, the two mathematical objects have several crucial differences. They have been introduced for different purposes by using two mathematical languages having different accuracies and on the basis of different methodological foundations. In fact, Levi-Civita does not discuss the distinction between numbers and numerals. His numbers have neither cardinal nor ordinal properties; they are build using a generic infinitesimal and only its rational powers are allowed; he uses symbol 1 in his construction; there is no any numeral system that would allow one to assign numerical values to these numbers; it is not explained how it would be possible to pass from d a generic infinitesimal h to a concrete one (see also the discussion above on the distinction between numbers and numerals). In no way the said above should be considered as a criticism with respect to results of Levi-Civita. The above discussion has been introduced in this text just to underline that we are in front of two different mathematical tools that should be used in different mathematical contexts.* It would be interesting to have a specialist in numerical analysis comment on Sergeyev's use of the term "numerical" to explain the difference between his grossone and an infinite element of the Levi-Civita field.


Sergeyev claims that his *grossone* has the properties of both ordinal and cardinal numbers. Does he give a definition that would ensure such properties, or is this claim merely a declarative pronouncement?


Following the publication of an article by Sergeyev in *EMS Surveys in Mathematical Sciences*, the editors [published the following clarification](http://www.ems-ph.org/journals/notice/emss/ed_note.pdf):



> 
> Statement of the editorial board
> 
> 
> We deeply regret that this article appears in this issue of the EMS Surveys in Mathematical Sciences.
> 
> 
> It was a serious mistake to accept it for publication. Owing to an unfortunate error, the entire processing of the paper, including the decision to accept it, took place without the editorial board being aware of what was happening. The editorial board unanimously dissociates itself from this decision. It is not representative of the very high level that we expect to see in our journal, which can be assessed from all other papers that we have published.
> 
> 
> Both editors-in-chief have assumed responsibility for these mistakes and resigned from their position. Having said that, we add that this journal would not exist without their dedication and years of hard work, and we wish to register our thanks to them.
> 
> 
> 


An interesting viewpoint of a computer scientist [is developed here](https://cs.stackexchange.com/a/85964/82128) (as well as a related discussion of legal issues in the *comments*).


The [unanimous statement of the EMS Surveys editors](http://www.ems-ph.org/journals/notice/emss/ed_note.pdf) is now fleshed out in [the Zentralblatt review](https://zbmath.org/?q=an:06856857) and [the MathSciNet review](https://mathscinet.ams.org/mathscinet-getitem?mr=3725242) also available [here](http://u.math.biu.ac.il/%7Ekatzmik/pirahodimetz.html).


Question. Does Sergeyev's grossone admit a consistent interpretation? Lolli in his answer argues that it does; others have argued otherwise.



What is... a grossone?
I do not understand what the bounty on this question is for, as it seems to me that the other answers were already rather devastating. Here is a semi-reasoned technical answer.


According to G. Lolli (the paper you cite) "Sergeyev is wary of the axiomatic method because he thinks that by adopting it we would be tied to the expressive power of a language in the description of mathematical objects and concepts." Serious mathematics requires serious adherence to the generally accepted standards of mathematics. Perhaps prof. Sergeyev thinks that he can surpass the limitations of formalization by taking a non-standard route to mathematics, but I would rather suspect that route will take him backwards in time and much closer to (a bad kind of) philosophy than most mathematicians would feel comfortable with.


Regarding the formalization by G. Lolli, I see no difference between what is done in the paper and non-standard arithmetic. A grossone $G$ is axiomatized by the infinitely many axioms $0 < G$, $1 < G$, $2 < G$, ... which is exactly how one can get non-standard arithmetic going. The paper does not even mention non-standard arithmetic. This is what you get for publishing logic papers in applied math journals.


So, it looks to me that grossones are a moving target with unclear and confused mathematical content, until one actually pins them down with a precise mathematical definition, only to find out they are not new at all.


**Update:** it was pointed out that none of the answers has commented on the computational part of the grossone theory. I had a look at three papers, found on the [infinity computer](http://www.theinfinitycomputer.com/arithmetic.html) web site:


1. The recommended paper to start with is Sergeyev Ya.D. (2010) [Lagrange Lecture: Methodology of numerical computations with infinities and infinitesimals](http://www.theinfinitycomputer.com/The_second_paper_to_read_(Lagrange_Lecture).pdf), Rendiconti del Seminario Matematico dell'Università e del Politecnico di Torino, 68(2), 95–113. It has a lot of informal descriptions and philosophy, some illustrative examples, but nothing that would actually describe a revolutionary new way of computing. Rather, it looks like ideas that could possibly lead to re-invention of non-standard arithmetic.
2. Sergeyev Ya.D. (2016) [The exact (up to infinitesimals) infinite perimeter of the Koch snowflake and its finite area](http://www.theinfinitycomputer.com/Koch.pdf), Communications in Nonlinear Science and Numerical Simulation, 31(1–3):21–29. I tried this paper because the title promised that there would be a concrete result in it. There is, of course, but again the theory of computation underlying the method is not properly explained. There are examples and analogies which again hint at something like non-standard arithmetic.
3. Sergeyev Ya.D. (2015) [Computations with grossone-based infinities](http://www.theinfinitycomputer.com/Sergeyev_UCNC2015.pdf), C.S. Calude, M.J. Dinneen (Eds.), Proc. of the 14th International Conference “Unconventional Computation and Natural Computation”, Lecture Notes in Computer Science, vol. 9252, Springer, 89-106. A pattern starts to emerge. Every paper contains a very long introduction to the philosophy and ideas about grossones, supported by illustrative examples, but there is no clear explanation of what is going on.


All three papers present an *equational system* for grossones, i.e., things like associativity, commutativity, and other equations one would expect. A smart person can use these to simplify expressions and thereby "compute" results. But a computational model requires a description of a *general* procedure for performing computations, whatever it is. Is there a method for normalizing expressions involving grossones? Or perhaps an abstract machine one can run? Or something else?


I suppose the infinity computer is hiding in the patent. We shall never know. And I have now wasted more time on this than 50 points of bounty are worth. If someone can point me at an actual description of a computational model (whether it be "axiomatic" or not) which is not composed of a series of analogies and good ideas, I might take another look.


