Fig. 2

Reachability computations. Function ForwardReachable, given source vertex s in hypergraph G, returns all hyperedges e for which \(\mathrm {tail}(e)\) is reachable by a hyperpath from s. Function BackwardTraceable, given sink vertex t in G, returns all hyperedges e for which some vertex \(v \in \mathrm {head}(e)\) is backward-traceable from t. These functions assume fields v.reached, e.marked, and e.count have been initialized to false, false, and \(|\mathrm {tail}(e)|\), respectively, for all v and e in G