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We define and study a relative perverse $t$-structure associated with any finitely presented morphism of schemes $f: X\to S$, with relative perversity equivalent to perversity of the restrictions to all geometric fibres of $f$. The…

Algebraic Geometry · Mathematics 2023-05-11 David Hansen , Peter Scholze

We survey nearby and vanishing cycles for both perverse sheaves and D-modules under analytic setting. Following ideas of A. Beilinson, M. Kashiwara and M. Saito, we explain in detail the proof of the comparison theorem between them in the…

Algebraic Geometry · Mathematics 2020-01-07 Lei Wu

We study the category $DM(S)$ of Beilinson motives (as described by Cisinski and Deglise) over a more or less general base scheme $S$, and establish several nice properties for a version $t_{hom}(S)$ of the perverse homotopy $t$-structure…

Algebraic Geometry · Mathematics 2015-04-08 Mikhail V. Bondarko

This article constructs Von Neumann invariants for constructible complexes and coherent D-modules on compact complex manifolds, generalizing the work of the author on coherent L 2-cohomology. We formulate a conjectural generalization of…

Algebraic Geometry · Mathematics 2022-03-15 Philippe Eyssidieux

We introduce and study the category of twisted modules over a triangular differential graded bocs. We show that in this category idempotents split, that it admits a natural structure of a Frobenius category, that a twisted module is…

Representation Theory · Mathematics 2019-06-25 R. Bautista , E. Pérez , L. Salmerón

Given a compact oriented manifold of dimension $n$ with a conically smooth stratification, we show that the moduli of $\mathcal{D}(k)$-valued constructible sheaves and the moduli of perverse sheaves are $(2-n)$-shifted Lagrangian. The…

Algebraic Geometry · Mathematics 2026-03-06 Merlin Christ , Enrico Lampetti

We show that the faithful highest weight hearts in an algebraic triangulated category are the serially faithful glued hearts, equivalently the hearts containing a dual pair of full exceptional collections in the sense of Bodzenta--Bondal…

Representation Theory · Mathematics 2026-05-04 Alessio Cipriani , Jon Woolf

Continuing our previous work on graded twisting of Hopf algebras and monoidal categories, we introduce a graded twisting construction for equivariant comodule algebras and module categories. As an example we study actions of quantum…

Quantum Algebra · Mathematics 2021-06-09 Julien Bichon , Sergey Neshveyev , Makoto Yamashita

We develop a unified approach for identifying spaces of stability conditions of triangulated categories arising from weighted marked surfaces with moduli spaces of quadratic differentials. This approach is based on the notion of a perverse…

Representation Theory · Mathematics 2024-06-26 Merlin Christ , Fabian Haiden , Yu Qiu

It is proved that for a commutative noetherian ring with dualizing complex the homotopy category of projective modules is equivalent, as a triangulated category, to the homotopy category of injective modules. Restricted to compact objects,…

Commutative Algebra · Mathematics 2007-05-23 Srikanth Iyengar , Henning Krause

We study the equivariant cohomology of spherical perverse sheaves on the affine Grassmannian of a connected reductive group $G$ with support in the affine Grassmannian of any Levi subgroup $L$ of $G$. In doing so, we extend the work of…

Representation Theory · Mathematics 2023-09-19 Mark Macerato

Perverse schobers are categorifications of perverse sheaves. In prior work we constructed a perverse schober on a partial compactification of the stringy K\"ahler moduli space (SKMS) associated by Halpern-Leistner and Sam to a…

Algebraic Geometry · Mathematics 2026-02-19 Špela Špenko , Michel Van den Bergh

We give a framework to produce constructible functions from natural functors between categories, without need of a morphism of moduli spaces to model the functor. We show using the Riemann-Hilbert correspondence that any natural (derived)…

Algebraic Geometry · Mathematics 2021-10-18 Nero Budur , Botong Wang

Let $G$ be a connected reductive algebraic group over an algebraically closed field $\Bbbk$ of characteristic $p \ge 0$, and let $\mathcal{N}$ be its nilpotent cone. Under mild hypotheses, we construct for each nilpotent $G$-orbit $C$ and…

Representation Theory · Mathematics 2022-03-10 Pramod N. Achar , William Hardesty

We study structurable algebras of skew-dimension one. We present two different equivalent constructions for such algebras: one in terms of non-linear isotopies of cubic norm structures, and one in terms of hermitian cubic norm structures.…

Rings and Algebras · Mathematics 2017-12-05 Tom De Medts

We develop a generalization to non-Witt spaces of the intersection homology theory of Goresky-MacPherson. The second author has described the self-dual sheaves compatible with intersection homology, and the other authors have described a…

Geometric Topology · Mathematics 2013-08-20 Pierre Albin , Markus Banagl , Eric Leichtnam , Rafe Mazzeo , Paolo Piazza

This note studies perverse sheaves of categories, or schobers, on Riemann surfaces, following ideas of Kapranov and Schechtman. For certain wall crossings in geometric invariant theory, I construct a schober on the complex plane, singular…

Algebraic Geometry · Mathematics 2018-11-20 W. Donovan

We briefly introduce the theory of perverse sheaves with special attention to the topological situation where strata can have odd dimension. This is part of a project to use perverse sheaves on the topological reductive Borel-Serre…

Algebraic Geometry · Mathematics 2016-12-06 Leslie Saper

Contraherent cosheaves are globalizations of contraadjusted or cotorsion modules over commutative rings obtained by gluing together over a scheme, with the colocalization functors $\operatorname{Hom}_R(S,{-})$ used for the gluing (where $S$…

Category Theory · Mathematics 2025-12-03 Leonid Positselski

We consider a natural generalisation of symmetric Nakayama algebras, namely, symmetric special biserial algebras with at most one non-uniserial indecomposable projective module. We describe the basic algebras explicitly by quiver and…

Representation Theory · Mathematics 2013-10-14 Nicole Snashall , Rachel Taillefer