Jernej
  • Member for 11 years, 1 month
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  • Slovenia
Reverse Graph Spectra Problem?
10 votes

Even asking whether a graph with a given spectrum exists is a tough question. This is witnessed by the open problem of determining whether there exists a graph of girth 5 diameter 2 and order 3250 ...

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Is there software for graph product calculation and visualization?
Accepted answer
6 votes

I think that Sage is the right thing for this task. Example. sage: G = digraphs.Circuit(40) sage: G = G.lexicographic_product(G) sage: G.show() Other graph products and algorithms are available ...

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Optimal upper bound on the number of non-isomorphic graphs with certain parameter
1 votes

This is just a partial answer mainly answering just $a)$ and $b)$ The number of non-isomorphic graphs is asymptotically equivalent to $$\frac{2^{n \choose 2}}{n!}$$ Almost all graphs are connected (...

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