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Equivariant category and topological complexity of wedges

Published online by Cambridge University Press:  15 September 2025

Cesar A. Ipanaque Zapata
Affiliation:
Departamento de Matemática, Instituto de Matemática e Estatística, Universidade de São Paulo, Rua do Matão 1010, São Paulo, Brasil
Denise De Mattos*
Affiliation:
Departamento de Matemática, Instituto de Ciências Matemáticas e de Computação, Universidade de São Paulo, Avenida Trabalhador São-carlense, 400, São Carlos, Brasil
*
Corresponding author: Denise De Mattos; Email: deniseml@icmc.usp.br

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 $X\vee Y$. As a direct application, we have that the wedge $\bigvee _{i=1}^m X_i$ is $G$-contractible if and only if each $X_i$ is $G$-contractible, for each $i=1,\ldots ,m$. One further application is to compute the equivariant category of the quotient $X/A$, for a $G$-space $X$ and an invariant subset $A$ such that the inclusion $A\hookrightarrow X$ is $G$-homotopic to a constant map $\overline {x_0}\,:\,A\to X$, for some $x_0\in X^G$. 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 $G$-connected $G$-CW-complexes $X$ and $Y$ under certain conditions.

Information

Type
Research Article
Copyright
© The Author(s), 2025. Published by Cambridge University Press on behalf of Glasgow Mathematical Journal Trust

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References

Aguilar, M., Gitler, S. and Prieto, C., Algebraic topology from a homotopical viewpoint (Universitext, Springer-Verlag, New York, 2002), xxx+478.10.1007/b97586CrossRefGoogle Scholar
Bayeh, M. and Soumen, S., Some aspects of equivariant LS-category, Topol. Appl. 196 (2015), 133154.10.1016/j.topol.2015.09.006CrossRefGoogle Scholar
Bayeh, M. and Sarkar, S., Orbit class and its applications, Fund. Math. 245(1) (2019), 5577.10.4064/fm551-4-2018CrossRefGoogle Scholar
Bredon, G., Introduction to compact transformation groups (Academic PressNew York-London1972), xiii+459.Google Scholar
Colman, H. and Grant, M., Equivariant topological complexity, Algebr. Geom. Topol. 12(4) (2013), 22992316.10.2140/agt.2012.12.2299CrossRefGoogle Scholar
Cornea, O., Lupton, G., Oprea, J. and Tanré, D., Lusternik-Schnirelmann category (Math. Surveys Monogr., 103 American Mathematical Society, Providence, RI, 2003), xviii+330.10.1090/surv/103CrossRefGoogle Scholar
Dugundji, J., Topology (Allyn and Bacon, Inc.Boston, MA, 1966), xvi+447.Google Scholar
Dranishnikov, A., Topological complexity of wedges and covering maps, Proc. Am. Math. Soc. 142(12) (2014), 43654376.10.1090/S0002-9939-2014-12146-0CrossRefGoogle Scholar
Dranishnikov, A. and Sadykov, R., The topological complexity of the free product, Math. Z. 293 (2019), 407416.10.1007/s00209-018-2206-yCrossRefGoogle Scholar
Fadell, E., The equivariant Ljusternik-Schnirelmann method for invariant functionals and relative cohomological index theories. in Topological Methods in Nonlinear Analysis, vol. 95 Sm. Math. Sup., (Presses Univ. Montreal, Montreal, Que., 1985), 4170.Google Scholar
Hatcher, A., Algebraic topology (Cambridge University PressCambridge, 2002), xii+544.Google Scholar
James, I., On category, in the sense of Lusternik-Schnirelmann, Topology 17(4) (1978), 331348. Elsevier10.1016/0040-9383(78)90002-2CrossRefGoogle Scholar
Lyusternik, L. A. and Shnirel’man, L. G., Topological methods in variational problems and their application to the differential geometry of surfaces, Uspekhi Matematicheskikh Nauk. 2(1) (1947), 166217, Russian Academy of Sciences, Steklov Mathematical Institute of Russian Academy of Sciences.Google Scholar
Lubawski, W. and Marzantowicz, W., Invariant topological complexity, Bull. Lond. Math. Soc. 47(1) (2015), 101117.10.1112/blms/bdu090CrossRefGoogle Scholar
Marzantowicz, W., A G-Lusternik-Schnirelman category of space with an action of a compact Lie group, Topology 28(4) (1989), 403412, Elsevier.10.1016/0040-9383(89)90002-5CrossRefGoogle Scholar
May, J. P., M. Cole, G. Comezaña, S. Costenoble, A. D. Elmendorf, J. P. C. Greenlees, L. G. Lewis, Jr., R. J. Piacenza, G. Triantafillou, and S. Waner. Equivariant homotopy and cohomology theory, in CBMS Regional Conf. Ser. in Math., 91 Published for the Conference Board of the Mathematical Sciences, Washington, DC (American Mathematical Society, Providence, RI, 1996), xiv+366.10.1090/cbms/091CrossRefGoogle Scholar
tom Dieck, T., Transformation groups (De Gruyter Stud. Math., 8 Walter de Gruyter & Co., Berlin, 1987), x+312.Google Scholar
Zapata, C. A. I., Non-contractible configuration spaces, Morfismos 22(1) (2018), 2739.Google Scholar
Zapata, C. A. I., Espaços de configurações no problema de planificação de movimento simultâneo livre de colisões, PhD Thesis (Instituto de Ciências Matemáticas e de Computação, Universidade de São Paulo, São Carlos), 321. doi: 10.11606/T.55.2022.tde-23052022-194647.Google Scholar