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arXiv · 1409.2717

The Higson-Roe exact sequence and $\ell^2$ eta invariants

Moulay-Tahar Benameur·Indrava Roy
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Abstract

The goal of this paper is to solve the problem of existence of an $\ell^2$ relative eta morphism on the Higson-Roe structure group. Using the Cheeger-Gromov $\ell^2$ eta invariant, we construct a group morphism from the Higson-Roe maximal structure group constructed in [HiRo:10] to the reals. When we apply this morphism to the structure class associated with the spin Dirac operator for a metric of positive scalar curvature, we get the spin $\ell^2$ rho invariant. When we apply this morphism to the structure class associated with an oriented homotopy equivalence, we get the difference of the $\ell^2$ rho invariants of the corresponding signature operators. We thus get new proofs for the classical $\ell^2$ rigidity theorems of Keswani obtained in [Ke:00].

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Moulay-Tahar Benameur, Indrava Roy. 2014-09-09. The Higson-Roe exact sequence and $\ell^2$ eta invariants. https://arxiv.org/abs/1409.2717

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