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622
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location Oxford, United Kingdom
age 50
visits member for 3 years, 10 months
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3h
awarded  Custodian
3h
reviewed Close Algorithm to find the “optimal” path in a given graph
3h
reviewed Close Explicit solution for a first order non-linear ODE
3h
reviewed Approve suggested edit on Non-trivial bounds for polynomials at a fixed point
3h
answered Complexity of Untwisting Polygons
3h
comment How prove this numerical solution we parameterize the integral equations
it's unclear what you ask. Do you mean that in the references you provide it was not proved or otherwise explained?
1d
reviewed Approve suggested edit on Changing Left Comodules into Right Comodules via the Antipode, and Comodule Tensor Products
1d
comment Fast computation of a Groebner basis - What is Possible
arguably the fastest Groebner bases implementations are www-salsa.lip6.fr/~jcf/Software
Sep
3
comment Is this problem on weighted bipartite graph solvable in polynomial time or it is NP-Complete
Why do you talk about finding a sequence? The order you pick up your $v_i$'s does not matter. Better talk about a subset of A. Do you allow weights to be negative? If not, then you trivially will have to take the whole A.
Sep
3
comment On the positivity of matrices
The vector space of matrices commuting with G has a basis {$I$,$\pi+\pi^4$,$\pi^2+\pi^3$}, where $\pi$ is the permutation matrix corresponding to the cyclic permutation (1,2,3,4,5). Thus $P$ will be a linear combination of these 3 matrices.
Sep
3
comment On the positivity of matrices
$G$ is able to guarantee that $P_{ij}=p$, as the dimension of the centraliser algebra (i.e. the vector space of matrices commuting with every element in $G$) is 3, which can be e.g. checked directly, or by computing the permutation character of $G$. All these things I don't define may be found in books on permutation groups, e.g. P.Cameron's books.google.co.uk/books/about/…
Sep
2
comment On the positivity of matrices
G depends on M only, and can be checked to be of size 10.
Sep
2
comment On the positivity of matrices
One way to conclude that for $P$ being the average over an orbit all these $P_{ij}=p$, would be to note that $P$ commutes with all $\Pi\in G$. One can check that the algebra of all matrices commuting with $G$ coincides with the algebra of symmetric circulant matrices. Thus $P$ has the claimed form.
Sep
2
revised On the positivity of matrices
added a link to the article I referred to
Sep
2
comment On the positivity of matrices
@Hansen: I don't see how you would complete a proof "by hand" without being able to reduce the number of parameters significantly.
Sep
2
comment On the positivity of matrices
here it is: journals.cambridge.org/article_S0305004100036185
Sep
2
awarded  Enlightened
Sep
1
comment On the positivity of matrices
What I am saying is: take an offending P, and average it over G. This gives a symmetric circulant matrix which is still offending, and which only depends on one parameter, $p$.
Sep
1
awarded  Nice Answer
Aug
31
comment On the positivity of matrices
@gondolf - you're welcome. Please click on "accept this answer" if you're happy with it.