Complementary classification approaches for protein sequences

'Department of Computer and Information Science, New Jersey Institute of Technology, Newark, NJ 07102, Cold Spring Harbor Laboratory, 100 Bungtown Road, Cold Spring Harbor, NY 11724, Courant Institute of Mathematical Sciences, New York University, 251 Mercer Street, New York, NY 10012, 'image Processing Section, Laboratory of Mathematical Biology, Division of Basic Sciences, National Cancer Institute, National Institutes of Health, Frederick, MD 21702 and 'Department of Mathematics, University of Maryland, College Park, MD 20742, USA