Department of Mathematics, Center for Mathematical Reserch, A.C., Apdo. Postal 402, 36000 Guanajuato, GTO, Mexico
Copyright © 2010 Omar Muñiz-Pérez. This is an open access article distributed under the
Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
We show that every U-space and every Banach space X satisfying are P(3)-convex, and we study the nonuniform version of P-convexity, which we call p-convexity.