Let \(B\subseteq Y\) and let \(p:Y\to B\) be a deformation retraction. Prove that \[ p_*:\pi_1(Y)\to\pi_1(B) \] is an isomorphism.
A deformation retraction induces an isomorphism on fundamental groups
P-TOP-WORKSHOP-HR-W2
- Area
- Topology
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- draft
P-TOP-WORKSHOP-HR-W2
Let \(B\subseteq Y\) and let \(p:Y\to B\) be a deformation retraction. Prove that \[ p_*:\pi_1(Y)\to\pi_1(B) \] is an isomorphism.