
top_sort(+Graph, -Sorted)

   Finds a topological ordering of the graph if one exists

Arguments
   Graph               a graph structure
   Sorted              a list of integer node numbers

Type
   library(graph_algorithms)

Description

    Finds a topological ordering of the graph, i.e. an ordering of the
    nodes such that all edges go from earlier to later nodes.
    Such an ordering exists if and only if the graph is acyclic.
    If the graph is cyclic, the predicate fails.
    
    In general, the ordering is not unique, an arbitrary one is computed.
    The complexity is O(Nnodes + Nedges).
    

Modes and Determinism
   top_sort(+, -) is semidet

Fail Conditions
   No topological ordering exists, i.e. the graph is cyclic

See Also
   graph_is_acyclic / 1, graph_cycles / 2
