### Abstract

Let $G$ be a compact Lie group. We present a criterion for the orbit spaces of two $G$-spaces to be homotopy equivalent and use it to obtain a quick proof of Webb's conjecture for compact Lie groups. We establish two Minami type formulae which present the $p$-localised spectrum

$\Sigma^\infty BG_+$ as an alternating sum of $p$-localised spectra $\Sigma^\infty BH_+$ for subgroup $H$ of $G$. The subgroups $H$ are calculated from the collections of the non-trivial elementary abelian $p$-subgroups of $G$ and the non-trivial $p$-radical subgroups of $G$. We also show that the Bousfield-Kan spectral sequences of the normaliser decompositions associated to these collections and to any $p$-local cohomology theory $h^*$, collapse at their $E_2$-pages to their vertical axes, and converge to $h^*(BG)$. An important tool is a topological version of Quillen's Theorem A which we prove.

$\Sigma^\infty BG_+$ as an alternating sum of $p$-localised spectra $\Sigma^\infty BH_+$ for subgroup $H$ of $G$. The subgroups $H$ are calculated from the collections of the non-trivial elementary abelian $p$-subgroups of $G$ and the non-trivial $p$-radical subgroups of $G$. We also show that the Bousfield-Kan spectral sequences of the normaliser decompositions associated to these collections and to any $p$-local cohomology theory $h^*$, collapse at their $E_2$-pages to their vertical axes, and converge to $h^*(BG)$. An important tool is a topological version of Quillen's Theorem A which we prove.

Original language | English |
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Pages (from-to) | 115-167 |

Number of pages | 53 |

Journal | Fundamenta Mathematicae |

Volume | 213 |

Issue number | 2 |

DOIs | |

Publication status | Published - 2011 |