Bulletin of the Belgian Mathematical Society - Simon Stevin

Realizing homotopy group actions

David Blanc and Debasis Sen

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For any finite group $G$, we define the notion of a \emph{Bredon homotopy action} of $G$, modelled on the diagram of fixed point sets \ensuremath{(\mathbf{X}\sp{H})\sb{H\leq G}} for a $G$-space $\mathbf{X}$, together with a pointed homotopy action of the group \ensuremath{N\sb{G}H/H} on \ensuremath{\mathbf{X}\sp{H}/(\bigcup\sb{H<K} \mathbf{X}\sp{K}).} We then describe a procedure for constructing a suitable diagram \ensuremath{\underline{\mbox{X}}:{\EuScript O}_{G}\op\to{\EuScript Top}} from this data, by solving a sequence of elementary lifting problems. If successful, we obtain a $G$-space \ensuremath{\mathbf{X}'}\ realizing the given homotopy information, determined up to Bredon $G$-homotopy type. Such lifting methods may also be used to understand other homotopy questions about group actions, such as transferring a $G$-action along a map \ensuremath{f:\mathbf{X}\to \mathbf{Y}. }

Article information

Bull. Belg. Math. Soc. Simon Stevin, Volume 21, Number 4 (2014), 685-710.

First available in Project Euclid: 23 October 2014

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Digital Object Identifier

Mathematical Reviews number (MathSciNet)

Zentralblatt MATH identifier

Primary: 55P91: Equivariant homotopy theory [See also 19L47]
Secondary: 55S35: Obstruction theory 55R35: Classifying spaces of groups and $H$-spaces 58E40: Group actions

Group actions equivariant homotopy type Bredon theory obstructions homotopy actions


Blanc, David; Sen, Debasis. Realizing homotopy group actions. Bull. Belg. Math. Soc. Simon Stevin 21 (2014), no. 4, 685--710. doi:10.36045/bbms/1414091009. https://projecteuclid.org/euclid.bbms/1414091009

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