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location Oxford, United Kingdom
age 51
visits member for 4 years
seen 12 hours ago

Dec
12
comment Exact arithmetic for real algebraic numbers
In fact, my pet project is to implement Thom encodings in Sage (a system some people in your department have quite a bit of experience with).
Dec
11
comment Exact arithmetic for real algebraic numbers
In fact yes, SARAG implements some of Thom encoding related algorithms. Although it shows signs of bitrot. I believe it's basically abandoned 4 or 5 years ago, and not all of its functions work on Maxima 5.26.0.
Dec
11
comment Exact arithmetic for real algebraic numbers
SARAG was an attempt to implement some of these algorithms in Maxima - not sure if it went as far as Thom encodings.
Dec
11
revised Seems like Reader monad composed with a strong monad produces a monad, am I right?
texifying
Dec
11
answered Exact arithmetic for real algebraic numbers
Dec
8
comment Pseudonyms of famous mathematicians
"Nestruev" loosely means "Non-streaming" in Russian, by the way... That is, we have a "non-streaming stream" for the name.
Dec
8
comment On linear automorphism on positive definite matrices.
Do you talk about automorphisms of the cone of the PSD matrices? Clearly, not all automorphisms are given by conjugations, ie maps $X\mapsto B^{-1}XB$, so it's indeed must be $X\mapsto B^\top XB$
Dec
8
comment Is the tensor product of polyhedra a polyhedron?
and once there are no $P_\ell$ and $Q_\ell$, a seemingly natural finite set of generators (?) of conv($P\otimes Q$) would be pairs of vertices and extreme rays.
Dec
7
comment Is the tensor product of polyhedra a polyhedron?
One wants to separate $P_c$ from $P_\ell$ to be able to say that $P_p+P_c$ are in the orthogonal complement to $P_\ell$. Whether it's useful here, is another question, of course.
Dec
7
revised Is the tensor product of polyhedra a polyhedron?
rectified the decomposition (*) into a more meaningful one
Dec
7
answered Is the tensor product of polyhedra a polyhedron?
Dec
6
comment SAT and Arithmetic Geometry
Vakil's work actually uses Mnev's Universality Theorem, which in a way has a computational flavour.
Dec
6
answered SAT and Arithmetic Geometry
Dec
6
comment SAT and Arithmetic Geometry
decidability over finite fields is trivial, as there are only finitely many choices!
Dec
5
comment A conjecture on solvablity of finite groups
and what is $\gamma_n(G)$?
Dec
3
answered How to work with infinite random graph(s) ?
Dec
1
comment bounding the sum of the entries of the inverse of a 0-1 matrix away from 1?
more generally, one can take block $2k\times 2k$ matrix of form $\binom{I\ B}{0\ I}$, where $B$ is all-1 $k\times k$ block. Then the sum of the entries of its inverse is $-k^2+2k$.
Dec
1
revised bounding the sum of the entries of the inverse of a 0-1 matrix away from 1?
added 7 characters in body
Dec
1
comment bounding the sum of the entries of the inverse of a 0-1 matrix away from 1?
@Gerhard, I found you a matrix you asked for, see Remark in the updated question.
Dec
1
revised bounding the sum of the entries of the inverse of a 0-1 matrix away from 1?
added 432 characters in body