by Gabriel R. Bitran and Thomas L. Magnanti."3-97-76."--handwritten on t.p. Cover title.Bibliography: p. 38-42.Supported in part by the U.S. Army Research Office (Durham) under contract no. DAHC04-732-0032 Supported in part by a Grant-in-Aid from Coca-Cola, U.S.A, administered at M.I.T. as OSP 27857