2 papers
math.CO2026
Counting spanning quasi-trees of ribbon graphs: determinants and #P-completeness
William Whistler
A quasi-tree of a connected ribbon graph is a spanning ribbon subgraph with exactly one boundary component; quasi-trees play the role of spanning trees in the topological graph the…
math.CO2026
Mixed partition functions are exactly the graph parameters of exponentially bounded edge-connection rank
William Whistler
We prove a conjecture of Regts and Sevenster: a complex-valued graph parameter with has exponentially bounded edge-connection rank if and only if it is a mixed…