JHC Whitehead - Bulletin of the American Mathematical Society, 1948 - ams.org
1. Introduction. Let A, BQA and Bf be compacta, which are1 ANR's (absolute neighbourhood
retracts). Let B'QA'where A'is a compactum, and let/:(A, B)~>(A\B') be a map such that ƒ|(A …