Given an undirected graph G = (V, E) and vertices s, , t t ; s2,t2, the problem is to determine whether or not G admits two vertex disjoint paths P, and P2 connecting s, with t, and s2 with t2, respectively. This problem is solved by an O ( n . m ) algorithm (n = IVJ, m = JElL An important by-product of the paper is a theorem stating that if G is 4â€¦Â (More)