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 Mar 18 comment Graphs cospectral with Cayley graphs regarding circulants, the first obvious case to try is the graphs with Paley graph parameters (29,14,6,7) on 29 vertices. If anyone cares, these graphs are given here maths.gla.ac.uk/~es/SRGs/29-14-6-7 (converting them into Sage-readable format would be great...) Mar 18 revised Graphs cospectral with Cayley graphs english Mar 18 comment Graphs cospectral with Cayley graphs no, I don't, I just don't know how to see an example quickly. While for the example I provide it is trivial. Mar 18 answered Graphs cospectral with Cayley graphs Mar 10 comment spectrum of Hadamard matrices in general, one cannot hope for a very nice answer, as one can multiply $H$ by an arbitrary $\pm 1$-permutation matrix, this does not break Hadamard property, but does change eigenvalues. Mar 10 revised spectrum of Hadamard matrices improved the answer, more proved Mar 10 comment spectrum of Hadamard matrices well, see my edit... Mar 10 revised spectrum of Hadamard matrices improved the answer Mar 10 reviewed Approve An inequality with spherical triangles Mar 10 answered spectrum of Hadamard matrices Mar 9 comment What does “game theory” cover and how should it be called? Historically, game theory has its roots in economics, and that's the area you call "narrow" for some reason. en.wikipedia.org/wiki/Theory_of_Games_and_Economic_Behavior was published in 1944, and most of the topics you mention in the beginning of your question have little to do with this area, it's simply something quite different. Mar 9 comment Simplicity of $A_n.$ compute the character table, and see that only the trivial character has a kernel. Mar 8 answered Relationship of Weisfeiler-Lehman algorithm to weak isomorphism of coherent algebras Mar 5 comment when is the independence number of a graph equals the clique cover number fort such graphs computing $\alpha(G)$ will be easy, as it's Lovasz $\theta(G)$ (or of the complement of $G$, depending upon its definition. Mar 5 comment a sum of ratios of quadratic forms are your $y_k$ and $x_k$ constants vectors? If yes, it's not clear why you cannot rewrite your $f$ as a ratio of 2 polynomials in $A$. If no, why does $f$ depend on $A$ alone? Mar 5 comment Real square roots of symmetric matrices Do you need $S$ real, or $S^2$ real suffices? Mar 3 comment Hypergeometric function asymptotics wait, isn't your function a polynomial of degree $n-1$? For small $x$ only linear term matters... Mar 3 comment Hypergeometric function asymptotics typically one would take an integral representation of the function, and use a method for integral asymptotics. E.g. if you use Euler integral representation for $_2 F_1(c-a,...;x)$ you'd expand the term $(1-xt)^{-c+a}$ into a series and take the biggest terms to get an asymptotic expansion by integration. Mar 3 comment Corresponding analogy for local compactness in algebraic geometry? in real algebraic geometry, the analog of compactness is usually closedness+boundedness... Feb 25 comment More general than semidefinite program? speaking about complexity, for SDPs in general is it not known, and so one has to tread carefully here.