Algebraic Topology · Problem 3F.3

Cohomology — Allen Hatcher

Mathematics — Topology · ext-A-Q-vanishing

Problem

Show that Ext(A,Q)=0\mathrm{Ext}(A, \mathbb{Q}) = 0 for all AA. [Consider the homology with Q\mathbb{Q} coefficients of a Moore space M(A,n)M(A, n).]

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