# nondescendants -- returns the nondescendants of a vertex of a digraph

## Synopsis

• Usage:
L = nondescendants (D, v)
• Inputs:
• D, an instance of the type Digraph,
• v, , a vertex of the digraph
• Outputs:
• L, a set, a set of all the nondescendants of v

## Description

The nondescendants of a directed graph are all the vertexSet u of D such that u is not reachable from v.

 i1 : D = digraph({a,b,c,d,e},{{a,b},{b,c},{b,d},{e,b}}); i2 : nondescendants (D, d) o2 = set {a, b, c, e} o2 : Set