On Upper Bound Graphs with Edge Operations

Abstract

In the upper bound graph of a poset $P$ with the vertex set $V(P)$, $xy$ is an edge if\nthere exists an $m\\in V(P)$ such that $x,y\\leq_P m$. We obtain some properties of edge\noperations of UB-graphs. According to these properties, we consider transformations on\nsplit UB-graphs.