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