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 Mar 28 comment How I can prove the equality $P^{P_{\operatorname{space}}}=NP^{P_{\operatorname{space}}}=P_{\operatorname{space}}^{P_{\operatorname{space}}}$ and for some reason it's not even possible to mention cstheory.stackexchange.com or cs.stackexchange.com as possible venues to migrate... Mar 28 reviewed Approve Hardy-Littlewood-Sobolev inequality in Lorentz spaces Mar 28 comment How I can prove the equality $P^{P_{\operatorname{space}}}=NP^{P_{\operatorname{space}}}=P_{\operatorname{space}}^{P_{\operatorname{space}}}$ there is cstheory.stackexchange.com/questions/tagged/… where many people who know all about complexity classes hang out Mar 28 comment Computing algebraic properties of trace fields, as given by SnapPy anyhow, if you just post here concrete examples of fields you want to know more about, some curious minds might compute things for you :) Mar 28 comment Computing algebraic properties of trace fields, as given by SnapPy snappy can be installed as a part of Sage (or at least it used to work). By the way, what makes you think that $a_1$,..,$a_n$ can be written in radicals? Mar 28 comment Computing algebraic properties of trace fields, as given by SnapPy aren't there computer algebra systems that will take the output you describe and compute what you need? E.g. Pari/GP and Sage should be able to tell you a lot about these fields. Mar 28 comment How I can prove the equality $P^{P_{\operatorname{space}}}=NP^{P_{\operatorname{space}}}=P_{\operatorname{space}}^{P_{\operatorname{space}}}$ I'm voting to close this question as off-topic because it belongs to cs.stackexchange.com Mar 26 comment Conjecture generalization of Feuerbach theorem and somes another theorems what is "nine points conic of P"? it would be more clear if you formulated this in terms of equations, than in geometric terms Mar 25 comment Let $S$ be the nonempty set of strongly regular graphs with given parameters. Must $S$ contain vertex transitive graph? @joro No doubts about the LMN result. I happen to know authors, I worked at the same lab some 10-15 years later... Also independently obtained by Paulus Mar 24 comment Can the following system of equations be solved analytically/in a closed form? it is not clear what you mean when you say that $v$'s can be chosen so that $a_i$'s are 0 or 1. If this is the case, you can just consider that 8 possible choices of $a_i$'s ? Mar 24 comment Can the following system of equations be solved analytically/in a closed form? regarding iterative solutions, you are looking for what is called Newton method (or many variants of it): en.wikipedia.org/wiki/… Mar 24 comment Let $S$ be the nonempty set of strongly regular graphs with given parameters. Must $S$ contain vertex transitive graph? One can also mention that these graphs, with orbits, are given on pages 175-179 of Lect. Notes Math. vol 558, Springer 1976. Mar 20 revised Self-complementary block designs more tags Mar 20 comment Self-complementary block designs OK, I just proved that you were right, see my edited answer... Mar 20 revised Self-complementary block designs show that we always come from a Hadamard matrix Mar 20 comment Self-complementary block designs It does not look obvious why one would always get a Hadamard matrix from the design: for this one has to show that for any two pairs $P$, $P'$ of complementary blocks, converted into $\pm 1$-vectors $v$, $v'$, one has $\langle v,v'\rangle=0$. Mar 19 answered Self-complementary block designs Mar 19 comment Self-complementary block designs I presume by self-complementarity you mean that the complement of each block is a block itself. (Like in the design of hyperplanes of an affine space over $\mathbb{F}_2$.) Mar 19 comment Self-complementary block designs Please clarify what exactly you mean by "self-complementary". That the design admits a polarity? Or is isomorphic to the dual (this would be the usual meaning of self-complementary)? Or something else? Or you just mean to say that the block size is half the number of points? Mar 18 comment Graphs cospectral with Cayley graphs One of them is surely a circulant (the Paley graph). I bet some (most?) of them do not have a transitive automorphism group, and this cannot be Cayley graphs.