Communications on Pure and Applied Mathematics is published monthly one volume per year by John Wiley & Sons Inc. Copyright © 1997 John Wiley & Sons Inc. All rights reserved. The journal publishes papers originating at or solicited by the Courant Institute of Mathematical Sciences . It features recent developments in applied mathematics mathematical physics and mathematical analysis. The topics include partial differential equations electrohydrogenonics computer science and applied mathematics. CPAM is devoted to mathematical contributions to the sciences; both theoretical and applied papers of original or expository type are included. Authors of papers accepted for publication are expected to submit their contributions formatted electronically in AMSTeX LaTeX or TeX.