The induced fundamental group homomorphism of the identity map is the identity map of the fundamental group/Statement

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Statement

Let [ilmath](X,\mathcal{ J })[/ilmath] be a topological space, let [ilmath]\text{Id}_X:X\rightarrow X[/ilmath] be the identity map, given by [ilmath]\text{Id}_X:x\mapsto x[/ilmath] and let [ilmath]p\in X[/ilmath] be given (this will be the basepoint of [ilmath]\pi_1(X,p)[/ilmath]) then[1]:

  • the induced map on the fundamental group [ilmath]\pi_1(X,p)[/ilmath] is equal to the identity map on [ilmath]\pi_1(X,p)[/ilmath]
    • That is to say [ilmath](\text{Id}_X)_*\eq\text{Id}_{\pi_1(X,p)}:\pi_1(X,p)\rightarrow\pi_1(X,p)[/ilmath] where [ilmath]\text{Id}_{\pi_1(X,p)} [/ilmath] is given by [ilmath]\text{Id}_{\pi_1(X,p)}:[f]\mapsto [f][/ilmath]

References

  1. Introduction to Topological Manifolds - John M. Lee