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Mosc. Math. J., 2025 Volume 25, Number 1, Pages 1–12 (Mi mmj899)

Torsion in the group of self-homotopy equivalences of a CW-complex

Mahmoud Benkhalifa

Department of Mathematics. College of Sciences, University of Sharjah, UAE

Abstract: Let $X$ be a simply connected CW-complex of dimension $n$. This paper aims to establish a link between the groups $\mathcal{E}(X)$ and $\Gamma_n(X)$. Here, $\mathcal{E}(X)$ represents the group of self-homotopy equivalences of $X$, while the group $\Gamma_n(X)$, which was intruduced by Whitehead, is the image of $\pi_n$ of the $(n-1)$-skeleton of $X$ in $\pi_n$ of the $n$-skeleton of $X$. This pursuit provides significant insights into discerning the presence of torsion elements within $\mathcal{E}(X)$.

Key words and phrases: whitehead's exact sequence, group of self-homotopy equivalences.

MSC: 55P10

Language: English

DOI: 10.17323/1609-4514-2025-25-1-1-12



© Steklov Math. Inst. of RAS, 2026