The universal property of bordism of commuting involutions

Fuente: arXiv
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Autori principali: Hausmann, Markus, Schwede, Stefan
Natura: Preprint
Pubblicazione: 2024
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author Hausmann, Markus
Schwede, Stefan
author_facet Hausmann, Markus
Schwede, Stefan
contents We propose a formalism to capture the structure of the equivariant bordism rings of smooth manifolds with commuting involutions. We introduce the concept of an oriented el$_2^{RO}$-algebra, an algebraic structure featuring representation graded rings for all elementary abelian 2-groups, connected by restriction homomorphisms, a pre-Euler class, and an inverse Thom class; this data is subject to one exactness property. Besides equivariant bordism, oriented global ring spectra also give rise to oriented el$_2^{RO}$-algebras, so examples abound. Inverting the inverse Thom classes yields a global 2-torsion group law. In this sense, our oriented el$_2^{RO}$-algebras are delocalized generalizations of global 2-torsion group laws. Our main result shows that equivariant bordism for elementary abelian 2-groups is an initial oriented el$_2^{RO}$-algebra. Several other interesting equivariant homology theories can also be characterized, on elementary abelian 2-groups, by similar universal properties. We prove that stable equivariant bordism is an initial el$_2^{RO}$-algebra with an invertible orientation; that Bredon homology with constant mod 2 coefficients is an initial el$_2^{RO}$-algebra with an additive orientation; and that Borel equivariant homology with mod 2 coefficients is an initial el$_2^{RO}$-algebra with an orientation that is both additive and invertible.
format Preprint
id arxiv_https___arxiv_org_abs_2406_00404
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle The universal property of bordism of commuting involutions
Hausmann, Markus
Schwede, Stefan
Algebraic Topology
55N22, 55N91, 55P91, 57R85
We propose a formalism to capture the structure of the equivariant bordism rings of smooth manifolds with commuting involutions. We introduce the concept of an oriented el$_2^{RO}$-algebra, an algebraic structure featuring representation graded rings for all elementary abelian 2-groups, connected by restriction homomorphisms, a pre-Euler class, and an inverse Thom class; this data is subject to one exactness property. Besides equivariant bordism, oriented global ring spectra also give rise to oriented el$_2^{RO}$-algebras, so examples abound. Inverting the inverse Thom classes yields a global 2-torsion group law. In this sense, our oriented el$_2^{RO}$-algebras are delocalized generalizations of global 2-torsion group laws. Our main result shows that equivariant bordism for elementary abelian 2-groups is an initial oriented el$_2^{RO}$-algebra. Several other interesting equivariant homology theories can also be characterized, on elementary abelian 2-groups, by similar universal properties. We prove that stable equivariant bordism is an initial el$_2^{RO}$-algebra with an invertible orientation; that Bredon homology with constant mod 2 coefficients is an initial el$_2^{RO}$-algebra with an additive orientation; and that Borel equivariant homology with mod 2 coefficients is an initial el$_2^{RO}$-algebra with an orientation that is both additive and invertible.
title The universal property of bordism of commuting involutions
topic Algebraic Topology
55N22, 55N91, 55P91, 57R85
url https://arxiv.org/abs/2406.00404