
inverse(+Succ, +Pred)

   Constrains elements of Succ to be the successors and Pred to be the predecessors of nodes in a digraph

Arguments
   Succ                A collection of N different variables or integers
   Pred                A collection  of N different variables or integers

Type
   library(ic_global)

Description

     Succ and Pred are list of N elements, representing a digraph of N nodes,
     where the i'th element of Succ and Pred represents the successor and
     predecessor of the node i respectively. The constraint enforces each
     node in the digraph to have one successor and one predessor node, and
     that if node y is the successor of node x, then node x is the
     predecessor of node y.

    This is currently a prototype -- the constraint has not been tested
    very extensive and little effort has been spent to optimise performance.
    We welcome any feedback on using this constraint.

     This constraint is known as inverse in the global constraint catalog,
     but with implicit node index based on the position in the list.  



