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bio website cs.ox.ac.uk/people/…
location Oxford, United Kingdom
age 50
visits member for 3 years, 9 months
seen 4 hours ago

May
26
answered Solving a quadratic matrix equation with non-squared matrix
May
26
comment What is the generic complexity of First Order Predicate Calculus?
I guess most of the people here, myself included, have no idea about generic complexity. Care to elaborate?
May
25
comment Existence of a real eigenvalue
it would help a lot if you spend few minutes typesetting entries in a readable way: e.g. the diagonal entry $M_{i+1,i+1}=1+4i-i^2-2n$ for all $i$ between 0 and $n-1$.
May
25
comment Correct spelling of names, Chebychev and Cholesky
@KConrad: as I used to speak reasonably good Dutch, I don't think I can be scared by phonetics any more. :-)
May
22
comment Correct spelling of names, Chebychev and Cholesky
Well, I can only say that English can't be a model example of "how to spell". It's more of "how to spell so that no-one without insider info will be able to pronounce correctly". :–)
May
22
answered Correct spelling of names, Chebychev and Cholesky
May
22
comment Correct spelling of names, Chebychev and Cholesky
there can't be any conclusive answer, as for different languages using Latin alphabet you get different spelling. In different times in Russia/USSR different rules regarding transliteration were in place; it used to be German, French, English (presently). Then there is a en.wikipedia.org/wiki/ISO_9 which stipulates the transliteration "Čebyšëv".
May
20
revised doubly-stochastic isomorphisms of graphs
added an explanation for Petersen graph
May
20
revised doubly-stochastic isomorphisms of graphs
corrected the definition of $A$
May
20
reviewed Reject suggested edit on nontrivial theorems with trivial proofs
May
20
comment doubly-stochastic isomorphisms of graphs
Actually, the same argument can be carried out for $A$ being the adjacency matrix of Petersen, with the obvious changes.
May
20
comment doubly-stochastic isomorphisms of graphs
I denote by $A$ the complement of Petersen's adjacency matrix
May
20
comment doubly-stochastic isomorphisms of graphs
In the paper I cite they proved that the complement to Petersen is not compact, and derive the non-compactness of the Petersen itself from it.
May
20
answered doubly-stochastic isomorphisms of graphs
May
20
comment doubly-stochastic isomorphisms of graphs
Is Petersen the smallest example? I guess it is small enough to attempt a computer enumeration of vertices of such a polytope. Has anyone tried this?
May
15
comment Is there an Ehrhart polynomial for Gaussian integers
Yeah, right, I didn't think straight. Sorry for noise.
May
14
comment Integrally closed polytopes from 01-matrices
Isn't every $p\in kP$ by definition equal to $p=q+...+q$, for $q\in P$? Or do you mean to have $p_i\neq p_j$ for $i\neq j$ ?
May
14
comment $xyz = \frac{7}{16}\left(\frac{2x - y - z}{3}\right)^3$ in nonvanishing integers
probably working in Sage will give you more info. It can identify the curve in certain database, etc...
May
14
answered Approaches to implicitly defining generating function
May
14
comment Approaches to implicitly defining generating function
(continuing) let $F$ be the GF for a recursively enumerable language with non-recursively enumerable complement, and $A$ the GF for the language of all words. Then $A-F$ is the GF for the complement of $F$, i.e. for a non-Chomsky language.