English

Equivariant category and Topological complexity of wedges

Algebraic Topology 2026-02-10 v5

Abstract

We prove the formula \begin{equation*} \text{cat}_G(X\vee Y)=\max\{\text{cat}_G(X),\text{cat}_G(Y)\} \end{equation*} for the equivariant category of the wedge XYX\vee Y. As a direct application, we have that the wedge i=1mXi\bigvee_{i=1}^m X_i is GG-contractible if and only if each XiX_i is GG-contractible, for each i=1,,mi=1,\ldots,m. One further application is to compute the equivariant category of the quotient X/AX/A, for a GG-space XX and an invariant subset AA such that the inclusion AXA\hookrightarrow X is GG-homotopic to a constant map x0:AX\overline{x_0}:A\to X, for some x0XGx_0\in X^G. Additionally, we discuss the equivariant and invariant topological complexities for wedges. For instance, as applications of our results, we obtain the following equalities: \begin{align*} \text{TC}_G(X\vee Y)&=\max\{\text{TC}_G(X),\text{TC}_G(Y),\text{cat}_G(X\times Y)\}, \text{TC}^G(X\vee Y)&=\max\{\text{TC}^G(X),\text{TC}^G(Y),_{X\vee Y}\text{cat}_{G\times G}(X\times Y)\}, \end{align*} for GG-connected GG-CW-complexes XX and YY under certain conditions. Keywords: (Equivariant) Lusternik-Schnirelmann category, equivariant and invariant topological complexities, GG-spaces, wedge product, smash product

Keywords

Cite

@article{arxiv.1809.08956,
  title  = {Equivariant category and Topological complexity of wedges},
  author = {Cesar A Ipanaque Zapata and Denise de Mattos},
  journal= {arXiv preprint arXiv:1809.08956},
  year   = {2026}
}

Comments

26 pages. We added a section in which we also discuss the equivariant and invariant topological complexities. Minor changes. New title. Final version. Comments are welcome