The Asymmetric Traveling Salesman Problem
  Starting with M(a), an n X n asymmetric cost matrix, Jonker and Volgenannt transformed it into a 2n X 2n symmetric cost matrix, M(s)where M(s) has unusual properties. One such property is that an optimal tour in M(s) yields an optimal tour in M(a). Modifying M(s), we apply the modified Floyd-Warshall algorithm to M(s). Due to the structure of M(s), we hopefully)can always obtain an optimal tour in M(a) in polynomial time.If theorem 1 in this paper is valid, since the asymmetric traveling salesman problem is NP-hard, P would equal NP. 
Howard Kleiman