A Note on Undirected Graphs Realizable as P.O. Sets
C. E. Haff, U. S. R. Murty, R. C. Wilton · Canadian Mathematical Bulletin · 1970
Let (P, ≥) be a p.o. set. The basis graph of (P, ≥) is defined to be the directed graph whose vertex set is P and in which the ordered pair 〈a, b〉 is an edge if and only if b covers a in (P, ≥). Let D be a directed graph. All graphs considered in this note are finite and are free of loops and multiple edges.