Algebraic Topology · Problem 4K.5

Homotopy Theory — Allen Hatcher

Mathematics — Topology · dold-thom-theorem

Problem

A map p:E→Bp: E \to B with BB not necessarily path-connected is defined to be a quasifibration if the following equivalent conditions are satisfied: (i) For all b∈Bb \in B and x0∈p−1(b)x_0 \in p^{-1}(b), the map p∗:πi(E,p−1(b),x0)→πi(B,b)p_*: \pi_i(E, p^{-1}(b), x_0) \to \pi_i(B, b) is an isomorphism for i>0i > 0 and π0(p−1(b),x0)→π0(E,x0)→π0(B,b)\pi_0(p^{-1}(b), x_0) \to \pi_0(E, x_0) \to \pi_0(B, b) is exact. (ii) The inclusion of the fiber p−1(b)p^{-1}(b) into the homotopy fiber FbF_b of pp over bb is a weak homotopy equivalence for all b∈Bb \in B. (iii) The restriction of pp over each path-component of BB is a quasifibration according to the definition in this section. Show these three conditions are equivalent, and prove Lemma 4K.3 for quasifibrations over non-path-connected base spaces.

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