$t$-perfection in $P_5$-free graphs

Abstract

A graph is called $t$-perfect if its stable set polytope is fully described by non-negativity, edge and odd-cycle constraints. We characterise $P_5$-free $t$-perfect graphs in terms of forbidden $t$-minors. Moreover, we show that $P_5$-free $t$-perfect graphs can always be coloured with three colours, and that they can be recognised in polynomial time.