Jernej
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 Sep29 answered Basic Questions in Graph Theory Sep28 asked Computing the number of positive and negative eigenvalues Sep7 comment Graph chromatic number and graph homomorphism? @user93620 Also take a look at the Mycielski construction en.wikipedia.org/wiki/Mycielskian Sep6 comment Diameter of a Connected Graph For the second question see here exwiki.org/mw/… Sep6 comment Complete graph invariant @ChrisGodsil In this case one just has to change in the above code : graphs.nauty_geng(str(n)): to graphs.cospectral_graphs(n) Sep5 revised Complete graph invariant added 71 characters in body Sep5 answered Complete graph invariant Sep4 accepted A variant of the Schwartz–Zippel lemma Sep1 comment What can we say about two graphs if they have similar adjacency matrices? Also if your graphs are regular then they have the same number of spanning trees as well. Sep1 comment What can we say about two graphs if they have similar adjacency matrices? Given two such graphs you can say that they have the same number of edges and triangles. Aug30 answered A variant of the Schwartz–Zippel lemma Aug29 comment A variant of the Schwartz–Zippel lemma @IgorShinkar As far as I understand this problem, yes. This is taken from an exercise section of a book, so I don't have any additional info except for what is written. Aug28 comment Is there any way to count cycles of given size by that graph's spectrum? Though, according to some result in the back of my mind it is possible to count the number of $4$-cycles of a graph given its spectrum and degree sequence. Aug28 answered Number of non-isomorphic connected graphs with m edges. Aug28 comment A variant of the Schwartz–Zippel lemma @IgorShinkar $f_2$ is actually $f_1$ - the coefficient of $x_1^{d_1}$ in $f.$ Aug28 revised A variant of the Schwartz–Zippel lemma edited body Aug28 asked A property of linear (error correcting) codes Aug26 asked A variant of the Schwartz–Zippel lemma Aug25 comment Automorphism groups of self-complementary graphs See also this exwiki.org/mw/… Aug23 accepted A summation identity over prime fields