Defaultgraphs.GraphOper
generic operation over imperative graphs
transitive reduction. Uses the transitive reduction algorithm from The Transitive Reduction of a Directed Graph, Aho, Garey and Ullman, 1972 - with the proviso that we know that our graph already is a transitive closure
module O : sig ... end
module S : sig ... end
val subgraph : G.t -> S.elt list -> G.t
extract the subgraph induced by the list l