Talk:Relative homology

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Could someone add relative cohomology? Charles Matthews 21:32, 19 October 2005 (UTC)

What is the definition of a morphism of pairs of topological spaces (as implied by the reference to a "category" of such pairs)? - 74.112.133.181 01:29, 12 May 2007 (UTC)

If (X,A) and (X',A') are both pairs, then a morphism between them is a continuous map which maps A to (a subset of) A'. - Saibod 18:33, 14 May 2007 (UTC)

Is it always true that or only when ? 69.234.22.18 21:09, 19 October 2007 (UTC)

only when n ≠ 0. the equality is true for all n if the right hand side is replaced by reduced homology. Mct mht (talk) 10:56, 14 December 2007 (UTC)

This should be made clear in the article. I'll edit it to reflect that. Hurkyl (talk) 04:08, 21 February 2008 (UTC)

The literature often requires (X,A) to be a good pair. I.e., A is closed and is a deformation retract of a neighborhood in X. Shouldn't this be mentioned, I wonder?69.202.65.222 (talk) 23:10, 14 September 2008 (UTC)

IIRC, the relative homology is a functor between Top² and Ab_∗. I think that this is more important than the functoriality of and that it should be added in the proper section. --SMP - talk (en) - talk (ca) 11:50, 21 June 2009 (UTC)