Isomorphisms of directed \(\overrightarrow{P}_3\)-graphs

Xueliang Li1, Yan Liu1, Biao Zhao2
1Center for Combinatorics and LPMC-TJKLC Nankai University, Tianjin 300071, China
2College of Mathematics and System Sciences Xinjiang University, Urumqi, Xinjiang 830046, China

Abstract

The directed \(\overrightarrow{P}_k\)-graph of a digraph \(D\) is obtained by representing the directed paths on \(k\) vertices of \(D\) by vertices. Two such vertices are joined by an arc whenever the corresponding directed paths in \(D\) form a directed path on \(k+1\) vertices or a directed cycle on \(k\) vertices in \(D\). In this paper, we give a necessary and sufficient condition for two digraphs with isomorphic \(\overrightarrow{P}_3\)-graphs. This improves a previous result, where some additional conditions were imposed.