Fredholm modules over categories, Connes periodicity and classes in cyclic cohomology

We replace a ring with a small $\mathbb{C}$-linear category $\mathcal{C}$, seen as a ring with several objects in the sense of Mitchell. We introduce Fredholm modules over this category and construct a Chern character taking values in the cyclic cohomology of $\mathcal{C}$. We show that this categor...

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Main Authors: Balodi, Mamta, Banerjee, Abhishek
Format: Article
Language:English
Published: Académie des sciences 2023-03-01
Series:Comptes Rendus. Mathématique
Online Access:https://comptes-rendus.academie-sciences.fr/mathematique/articles/10.5802/crmath.429/
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author Balodi, Mamta
Banerjee, Abhishek
author_facet Balodi, Mamta
Banerjee, Abhishek
author_sort Balodi, Mamta
collection DOAJ
description We replace a ring with a small $\mathbb{C}$-linear category $\mathcal{C}$, seen as a ring with several objects in the sense of Mitchell. We introduce Fredholm modules over this category and construct a Chern character taking values in the cyclic cohomology of $\mathcal{C}$. We show that this categorified Chern character is homotopy invariant and is well-behaved with respect to the periodicity operator in cyclic cohomology. For this, we also obtain a description of cocycles and coboundaries in the cyclic cohomology of $\mathcal{C}$ (and more generally, in the Hopf cyclic cohomology of a Hopf-module category) by means of DG-semicategories equipped with a trace on endomorphism spaces.
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record_format Article
series Comptes Rendus. Mathématique
spelling doaj-art-ab98b846e65e4d82b387dcee6e1f579e2025-02-07T11:07:00ZengAcadémie des sciencesComptes Rendus. Mathématique1778-35692023-03-01361G361765210.5802/crmath.42910.5802/crmath.429Fredholm modules over categories, Connes periodicity and classes in cyclic cohomologyBalodi, Mamta0Banerjee, Abhishek1Department of Mathematics, Indian Institute of Science, Bangalore - 560012, IndiaDepartment of Mathematics, Indian Institute of Science, Bangalore - 560012, IndiaWe replace a ring with a small $\mathbb{C}$-linear category $\mathcal{C}$, seen as a ring with several objects in the sense of Mitchell. We introduce Fredholm modules over this category and construct a Chern character taking values in the cyclic cohomology of $\mathcal{C}$. We show that this categorified Chern character is homotopy invariant and is well-behaved with respect to the periodicity operator in cyclic cohomology. For this, we also obtain a description of cocycles and coboundaries in the cyclic cohomology of $\mathcal{C}$ (and more generally, in the Hopf cyclic cohomology of a Hopf-module category) by means of DG-semicategories equipped with a trace on endomorphism spaces.https://comptes-rendus.academie-sciences.fr/mathematique/articles/10.5802/crmath.429/
spellingShingle Balodi, Mamta
Banerjee, Abhishek
Fredholm modules over categories, Connes periodicity and classes in cyclic cohomology
Comptes Rendus. Mathématique
title Fredholm modules over categories, Connes periodicity and classes in cyclic cohomology
title_full Fredholm modules over categories, Connes periodicity and classes in cyclic cohomology
title_fullStr Fredholm modules over categories, Connes periodicity and classes in cyclic cohomology
title_full_unstemmed Fredholm modules over categories, Connes periodicity and classes in cyclic cohomology
title_short Fredholm modules over categories, Connes periodicity and classes in cyclic cohomology
title_sort fredholm modules over categories connes periodicity and classes in cyclic cohomology
url https://comptes-rendus.academie-sciences.fr/mathematique/articles/10.5802/crmath.429/
work_keys_str_mv AT balodimamta fredholmmodulesovercategoriesconnesperiodicityandclassesincycliccohomology
AT banerjeeabhishek fredholmmodulesovercategoriesconnesperiodicityandclassesincycliccohomology