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Apr
5
comment Dominated convergence theorem and fundamental lemma
this looks like a meaningful question...
Mar
26
comment Proving that $(e^x+1)^{1/3}$ has no elementary antiderivative
well, consider my answer being done by computer, not me :-)
Mar
22
comment Determinant of a Vandermonde matrix of roots of monic polynomial with integer coefficients
the square of the Vandermonde is a symmetric function, and thus Per's argument applies.
Jan
21
comment How unitarize an irreducible representation of a finite group?
In fact you don't need to compute eigenvalues and eigenvectors. Although you will still need to compute square roots of real cyclotomics at the end, as I mentioned in GAP forum.
Dec
26
comment symmetrizability of generalised cartan matrix
either wikipedia is wrong, or this is by definition: en.wikipedia.org/wiki/Cartan_matrix en.wikipedia.org/wiki/Symmetric_matrix#Symmetrizable_matrix
Sep
29
comment What is the second least non prime order of a simple group?
PSL(3,2), not PSL(7,2)
Sep
28
comment divisibility of number of solutions of $x_1+\cdots+x_k=n$
I'm not 100% sure, but it seems that if $\gcd(n,k)=1$ then all the $k$ cyclic $k$-shifts of a solution are different. This means that the number of solutions is divisible by $k$.
Dec
4
comment Complexity of multiplying Cauchy matrix by a vector
I've edited the question. Hopefully someone reviews the changes.
Nov
29
comment Complexity of multiplying Cauchy matrix by a vector
this is the problem of multiplying a vector by a matrix, not solving linear equations...
Sep
17
comment a question about odd cycle
isn't a proof for $k=1$ trivial? Take 2 vertices $u_0,u_2$ at distance 2 (say, $u_0u_1u_2$ is a path connecting them). Then there should be a length $2k+1=3$ path $u_0v_1v_2u_2$ between them, too. Now take all the vertices $u_i$ and $v_j$ - they form a 5-path, right?