Proving a directed analogue of the Gyárfás-Sumner conjecture for orientations of $P_4$

Linda Cook, Tomáš Masařík, Marcin Pilipczuk +2

An oriented graph is a digraph that does not contain a directed cycle of length two. An (oriented) graph $D$ is $H$-free if $D$ does not contain $H$ as an induced sub(di)graph. The…