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location Oxford, United Kingdom
age 50
visits member for 3 years, 8 months
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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!
Jul
31
comment Smallest Connected Graph for Given Degree Sequence
regarding the uniqueness, very few graphs are characterized by their degree sequences. E.g. cubic graphs (all $d_k=3$) on $n$ vertices form a very big family...
Jul
31
comment Smallest Connected Graph for Given Degree Sequence
in what sense can you talk about the smallest graph here? All such graphs have the same number of vertices and edges.
Jul
31
comment Is there an infinite J-group?
how about en.wikipedia.org/wiki/Tarski_monster_group
Jul
30
reviewed Reject suggested edit on A Book You Would Like to Write
Jul
2
awarded  Curious
Jun
30
reviewed Approve suggested edit on Ordinary Generating Function for Bell Numbers
Jun
30
answered On the Suzuki group
Jun
27
comment dual problem of SDP
this looks like a standard exercise in the duality theory of SDPs, apart from there seems to be a typo in the objective function (unless there is an extra assumption that $x$ is real).
Jun
26
reviewed Approve suggested edit on Why do Bernoulli numbers arise everywhere?
Jun
24
comment Permutation Groups Containing non-commuting $p$-cycles
@GeoffRobinson: I guess it's due to Frieder's primitivity argument really needing prime length. Anyhow, it seems that Jordan's result can often tell you more about groups in your theorem.
Jun
20
reviewed Approve suggested edit on Empty node in cactus construction
Jun
19
comment Find a path that covers as many nodes as possible
@NickS : mere existence of a walk of $\ell$ steps is NP-hard, disregarding the edge lengths.
Jun
19
comment Find a path that covers as many nodes as possible
@NickS : calculating powers usually allows one to solve shortest paths problems; here it's more like longest path problem...
Jun
19
comment Find a path that covers as many nodes as possible
right, the poster means "walk".
Jun
19
comment Permutation Groups Containing non-commuting $p$-cycles
@FriederLadisch : just a remark that "generated" is important here. It seems that you might have primitive action on each block this way (and this is indeed a reduction to the primitive case, more or less).