Number of Subgraphs and Their Converses in Tournaments and New Digraph Polynomials

Jiangdong Ai, Gregory Gutin, Hui Lei +2

An oriented graph $D$ is converse invariant if, for any tournament $T$, the number of copies of $D$ in $T$ is equal to that of its converse $-D$. El Sahili and Ghazo Hanna [J. Grap…