Ideal Perturbation Lemma
Abstract
Description
We explain the essence of perturbation problems. The key to understanding is the structure of chain homotopy equivalence -- the standard one must be replaced by a finer notion which we call a strong chain homotopy equivalence. We prove an Ideal Perturbation Lemma and show how both new and classical results follow from this ideal statement.
Introduction substantially revised and some typos corrected
Introduction substantially revised and some typos corrected