Talk:Reducible Poincaré Complexes (Ex)
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Revision as of 17:58, 30 May 2012 by Andrzej Czarnecki (Talk | contribs)
1. Let's quickly prove the mentioned theorem of Wall. Assume that is connected. The collection of top-dimensional -cells is such that is connected - otherwise any two connected components would give two independent classes in . Assume that is pointed and that all attaching maps are pointed as well. We can take to be the -skeleton of and the unique -cell to have the attaching map
begginning with the pinching map.