Equivariant toric geometry and Euler-Maclaurin formulae

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Main Authors: Cappell, Sylvain E., Maxim, Laurenţiu, Schürmann, Jörg, Shaneson, Julius L.
Format: Preprint
Published: 2023
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author Cappell, Sylvain E.
Maxim, Laurenţiu
Schürmann, Jörg
Shaneson, Julius L.
author_facet Cappell, Sylvain E.
Maxim, Laurenţiu
Schürmann, Jörg
Shaneson, Julius L.
contents We consider equivariant versions of the motivic Chern and Hirzebruch characteristic classes of a quasi-projective toric variety, and extend many known results from non-equivariant to the equivariant setting. The corresponding generalized equivariant Hirzebruch genus of a torus-invariant Cartier divisor is also calculated. Further global formulae for equivariant Hirzebruch classes are obtained in the simplicial context by using the Cox construction and the equivariant Lefschetz-Riemann-Roch theorem. Alternative proofs of all these results are given via localization at the torus fixed points in equivariant K- and homology theories. In localized equivariant K-theory, we prove a weighted version of a classical formula of Brion for a full-dimensional lattice polytope. We also generalize to the context of motivic Chern classes the Molien formula of Brion-Vergne. Similarly, we compute the localized Hirzebruch class, extending results of Brylinski-Zhang for the localized Todd class. We also elaborate on the relation between the equivariant toric geometry via the equivariant Hirzebruch-Riemann-Roch and Euler-Maclaurin type formulae for full-dimensional simple lattice polytopes. Our results provide generalizations to arbitrary coherent sheaf coefficients, and algebraic geometric proofs of (weighted versions of) the Euler-Maclaurin formulae of Cappell-Shaneson, Brion-Vergne, Guillemin, etc., via the equivariant Hirzebruch-Riemann-Roch formalism. Our approach, based on motivic characteristic classes, allows us to obtain such Euler-Maclaurin formulae also for (the interior of) a face, or for the polytope with several facets removed. We also prove such results in the weighted context, and for Minkovski summands of the given full-dimensional lattice polytope. Some of these results are extended to local Euler-Maclaurin formulas for the tangent cones at the vertices of the given lattice polytope.
format Preprint
id arxiv_https___arxiv_org_abs_2303_16785
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Equivariant toric geometry and Euler-Maclaurin formulae
Cappell, Sylvain E.
Maxim, Laurenţiu
Schürmann, Jörg
Shaneson, Julius L.
Algebraic Geometry
Algebraic Topology
14M25, 14C17, 14C40, 52B20, 65B15, 19L47, 55N91
We consider equivariant versions of the motivic Chern and Hirzebruch characteristic classes of a quasi-projective toric variety, and extend many known results from non-equivariant to the equivariant setting. The corresponding generalized equivariant Hirzebruch genus of a torus-invariant Cartier divisor is also calculated. Further global formulae for equivariant Hirzebruch classes are obtained in the simplicial context by using the Cox construction and the equivariant Lefschetz-Riemann-Roch theorem. Alternative proofs of all these results are given via localization at the torus fixed points in equivariant K- and homology theories. In localized equivariant K-theory, we prove a weighted version of a classical formula of Brion for a full-dimensional lattice polytope. We also generalize to the context of motivic Chern classes the Molien formula of Brion-Vergne. Similarly, we compute the localized Hirzebruch class, extending results of Brylinski-Zhang for the localized Todd class. We also elaborate on the relation between the equivariant toric geometry via the equivariant Hirzebruch-Riemann-Roch and Euler-Maclaurin type formulae for full-dimensional simple lattice polytopes. Our results provide generalizations to arbitrary coherent sheaf coefficients, and algebraic geometric proofs of (weighted versions of) the Euler-Maclaurin formulae of Cappell-Shaneson, Brion-Vergne, Guillemin, etc., via the equivariant Hirzebruch-Riemann-Roch formalism. Our approach, based on motivic characteristic classes, allows us to obtain such Euler-Maclaurin formulae also for (the interior of) a face, or for the polytope with several facets removed. We also prove such results in the weighted context, and for Minkovski summands of the given full-dimensional lattice polytope. Some of these results are extended to local Euler-Maclaurin formulas for the tangent cones at the vertices of the given lattice polytope.
title Equivariant toric geometry and Euler-Maclaurin formulae
topic Algebraic Geometry
Algebraic Topology
14M25, 14C17, 14C40, 52B20, 65B15, 19L47, 55N91
url https://arxiv.org/abs/2303.16785