Affiliation: | 1. Department of Chemical Engineering , The University of Texas at Austin , Austin, Texas, 78712;2. Instituto de Investigaciones en Matemáticas Aplicadas y en Sistemas, Universidad Nacional Autónoma de México , México, D.F., 20;3. Department of Computer Sciences , The University of Texas at Austin , Austin, Texas, 78712;4. Computervision Corp. , Bedford, Mass, 01730 |