4,204 reputation
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bio website cs.ox.ac.uk/people/…
location Oxford, United Kingdom
age 51
visits member for 4 years
seen 16 hours ago

Aug
8
answered Possible degrees of faithful projective representations of $\mathrm{PSL}(k,q)$ and $\mathrm{Sp}(2k,q)$ over complex numbers
Aug
8
comment Possible degrees of faithful projective representations of $\mathrm{PSL}(k,q)$ and $\mathrm{Sp}(2k,q)$ over complex numbers
The poster most probably doesn't have access to Magma. (well, the same computations can be done in GAP (gap-system.org), which is free...)
Aug
6
comment When polynomial GI implies polynomial (edge) colored GI?
other questions are harder :)
Aug
6
comment When polynomial GI implies polynomial (edge) colored GI?
the explicit generators are trivial to find. Indeed, the action on the degree 2 vertices is just the action of $S_n$ on pairs {[12],[13],..,[pq]...}, for p<q.
Aug
6
comment When polynomial GI implies polynomial (edge) colored GI?
Actually if you read details in A052565 you'll see that it is n! for n>3.
Aug
6
comment When polynomial GI implies polynomial (edge) colored GI?
The case $n=3$ is exceptional, as the resulting graph is hexagon, so you get 12. Then for all $n\geq 4$ you should just get $n!$.
Aug
6
comment When polynomial GI implies polynomial (edge) colored GI?
OK; then please write "the subdivision", not just "subdivision". Anyhow, I am sure that the automorphism group of such a graph is easy to describe for any $n$. (not sure though what you mean by "tractable to compute" - by some particular algorithm? Or do you mean "describe"?)
Aug
6
comment When polynomial GI implies polynomial (edge) colored GI?
Do you mean a particular subdivision of $K_n$? (I have trouble reading English with missing articles). In your description, you seem to have defined a family of subdivisions for a given $n$, not just one particular.
Aug
6
comment When polynomial GI implies polynomial (edge) colored GI?
How is A052565 relevant here? What are these numbers counting?
Aug
5
comment Software tools for medium-scale systems of polynomial equations
yes, I agree that it's quite probable that the exact original polynomials have a common real 0. IMHO trying numerical methods to improve upon 2*10^-9 is pretty much pointless here.
Aug
5
comment Software tools for medium-scale systems of polynomial equations
SQP most probably will terminate in a local minimum. I'd be surprised if any restarts from such a minimum are attempted.
Aug
4
answered Software tools for medium-scale systems of polynomial equations
Aug
3
comment Software tools for medium-scale systems of polynomial equations
as you have a sum squares cost function to optimise, I suppose the most natural method will be one based on semidefinite programming (a.k.a. Lasserre hierarchies). Did you try these?
Aug
3
comment Software tools for medium-scale systems of polynomial equations
your link does not seem to work; it leads to the URL raw.githubusercontent.com/alexflint/polygamy/master/out/… which does not show up.
Jul
31
accepted centralizer of the order 2^k cyclic permutation matrix over F_2
Jul
31
answered centralizer of the order 2^k cyclic permutation matrix over F_2
Jul
31
comment Smallest Connected Graph for Given Degree Sequence
ok, i edited the question as to make it clear here.
Jul
31
revised Smallest Connected Graph for Given Degree Sequence
english fix
Jul
31
comment Smallest Connected Graph for Given Degree Sequence
ok, but what are you minimizing?
Jul
31
comment Smallest Connected Graph for Given Degree Sequence
I don't understand. The number of vertices and the number of edges are already GIVEN!