English

On the discontinuity of the $\pi_1$-action

Algebraic Topology 2020-04-14 v1 General Topology

Abstract

We show the classical π1\pi_1-action on the nn-th homotopy group can fail to be continuous for any nn when the homotopy groups are equipped with the natural quotient topology. In particular, we prove the action π1(X)×πn(X)πn(X)\pi_1(X)\times\pi_n(X)\to\pi_n(X) fails to be continuous for a one-point union X=AHnX=A\vee \mathbb{H}_n where AA is an aspherical space such that π1(A)\pi_1(A) is a topological group and Hn\mathbb{H}_n is the (n1)(n-1)-connected, n-dimensional Hawaiian earring space Hn\mathbb{H}_n for which πn(Hn)\pi_n(\mathbb{H}_n) is a topological abelian group.

Keywords

Cite

@article{arxiv.1807.07976,
  title  = {On the discontinuity of the $\pi_1$-action},
  author = {Jeremy Brazas},
  journal= {arXiv preprint arXiv:1807.07976},
  year   = {2020}
}

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13 pages