Oper.MakeBasic operations over graphs
type g = B.G.ttransitive_closure ?reflexive g returns the transitive closure of g (as a new graph). Loops (i.e. edges from a vertex to itself) are added only if reflexive is true (default is false).
add_transitive_closure ?reflexive g replaces g by its transitive closure. Meaningless for persistent implementations (then acts as transitive_closure).
transitive_reduction ?reflexive g returns the transitive reduction of g (as a new graph). Loops (i.e. edges from a vertex to itself) are removed only if reflexive is true (default is false).
replace_by_transitive_reduction ?reflexive g replaces g by its transitive reduction. Meaningless for persistent implementations (then acts as transitive_reduction).
mirror g returns a new graph which is the mirror image of g: each edge from u to v has been replaced by an edge from v to u. For undirected graphs, it simply returns g. Note: Vertices are shared between g and mirror g; you may need to make a copy of g before using mirror
complement g returns a new graph which is the complement of g: each edge present in g is not present in the resulting graph and vice-versa. Edges of the returned graph are unlabeled.
intersect g1 g2 returns a new graph which is the intersection of g1 and g2: each vertex and edge present in g1 *and* g2 is present in the resulting graph.