Colocality and twisted sums of Banach spaces

[摘要] Using the relation between subspaces of Banach spaces and quotients of their duals, we introduce the concept of colocality to give a new method that guarantees the existence of nontrivial twisted sums in which finite quotients play a major role (Theorem 1.7). An interesting point is that no restrictions are imposed on the quotients, only on the various subspaces. New examples of nontrivial twisted sums are given. (c) 2005 Elsevier Inc. All rights reserved.

[发布日期] 2006-11-15

[关键词] Banach space;sequence space;locally bounded space;complemented subspace;three space problem;operator