6 problems

Series-parallel chromatic-root bound. There exists a universal constant $C<\infty$ such that, for every series-parallel graph $G$ of maximum degree $k$, every chromatic root $z$ li…

Let $\mathcal S$ be the class of series-parallel graphs. Biro, Collado and Zamora's conjecture. … The indeque ratio measures the asymptotic minimum proportion of vertices that can…

NP-hardness conjecture. Minimum Eternal Vertex Cover is NP-hard on series-parallel graphs.

Locally series-parallel graph characterization conjecture. The following are equivalent:

Let $\Delta_0$ be the threshold parameter in Theorem, concerning the accumulation of chromatic zeros of leaf joined trees relative to the degree bound $\Delta$. The degree-three th…

Let $B_{5/27}(1)$ denote the disk of radius $5/27$ centered at $1$, and let $Z(G;q)$ be the chromatic polynomial of a series-parallel graph $G$. The punctured-disk zero-free conjec…