In graph theory, reachability refers to the ability to get from one vertex to another within a graph.
A vertex s can reach a vertex t (and t is reachable from s) if there exists a sequence of adjacent vertices (i.e. a walk) which starts with s and ends with t.
The Reachability Matrix can be derived from the Adjacency matrix if transitive multi-level
Usually there are several Adjacency matrices that have the same Reachability Matrix. However, in forming a digraph from a Reachability Matrix, a valuable digraph uniqueness can be achieved by applying the criterion that the digraph have the minimum possible number of edges that maintains reachability,represented by entries of 1 in the reachability matrix.