D, an object of class Digraph (missing documentation), which has the direct edge (a,b) if and only if a < b in P and if a ≤c ≤b then c = a or c = b.
Description
The Hasse diagram of a poset is a Digraph (missing documentation) with vertices given by the ground set of P and which has the direct edge (a,b) if and only if a < b in P and there exists no c such that a < c < b.