transpose/3¶

transpose(+ Graph, - NewGraph)*

Unify NewGraph with a new graph obtained from Graph by replacing all edges of the form V1-V2 by edges of the form V2-V1. The cost is O(|V|^2). In the next example:

 ?- transpose([1-[3,5],2-[4],3-[],
 4-[5],5-[],6-[],7-[],8-[]], NL).

 NL = [1-[],2-[],3-[1],4-[2],5-[1,4],6-[],7-[],8-[]]

Notice that an undirected graph is its own transpose.