ABSTRACT
In this section X will be an R-oriented n-dimensional manifold, A a closed subset. Let U = X – A. We have seen that there is a canonical homomorphism i : H c q ( U ) → H c q ( X ) https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429502408/295d3acc-dfa3-4421-a2d3-a9c22ffb681c/content/eq1085.tif"/>
