3 problems

Let $C_m$ be the cycle graph on $m$ vertices, $K_2$ and $C_3$ the indicated factors, and let $G$ be the Petersen graph. For nonnegative exponents, the displayed Cartesian products…

Petersen graph flow-number conjecture.

Chromatic separation conjecture. (a) Two signed Petersen graphs that are not switching isomorphic have different zero-free chromatic polynomials; in particular, they have different…