by Donald Goldfarb, Zhiying Jin, James B. Orlin.
Includes bibliographical references (p. 15-16).
Supported in part by NSF. DMS 94-14438 DMS 95-27124 Supported in part by DOE. DE-FG02-92ER25126 Supported as well by grants from UPS and ONR. N00014-96-1-0051