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Alternative titles of this paper would have been `Index theory without index' or `The Baum-Connes conjecture without Baum.' In 1989, Rieffel introduced an analytic version of deformation quantization based on the use of continuous fields of…

Mathematical Physics · Physics 2009-11-07 N. P. Landsman

In [10] it was shown that there is a mapping class group-equivariant deformation retraction of the Teichm\"uller space of a closed surface onto a CW complex with dimension equal to the virtual cohomological dimension of the mapping class…

Geometric Topology · Mathematics 2025-09-09 Ingrid Irmer

We define a differential graded algebra associated to Legendrian knots in thickened convex surfaces $\Sigma\times \mathbb{R}$. The algebra is defined in the same spirit as the Chekanov-Eliashberg DGA for Legendrians in $\mathbb{R}^3$, but…

Symplectic Geometry · Mathematics 2026-05-14 Nancy Mae Eagles , Zijian Rong

We prove sharp $\ell^2$-decoupling inequalities for non-degenerate complex curves via the bilinear argument due to Guo--Li--Yung--Zorin-Kranich, which in turn is inspired by the efficient congruencing argument of Wooley. Secondly,…

Classical Analysis and ODEs · Mathematics 2026-03-03 Robert Schippa

Differential calculus on discrete spaces is studied in the manner of non-commutative geometry by representing the differential calculus by an operator algebra on a suitable Krein space. The discrete analogue of a (pseudo-)Riemannian metric…

Mathematical Physics · Physics 2007-05-23 Eric Forgy , Urs Schreiber

We show that the crossed modules and bicovariant different calculi on two Hopf algebras related by a cocycle twist are in 1-1 correspondence. In particular, for quantum groups which are cocycle deformation-quantisations of classical groups…

Quantum Algebra · Mathematics 2009-10-31 Shahn Majid , Robert Oeckl

Recently developed applications in the field of machine learning and computational physics rely on automatic differentiation techniques, that require stable and efficient linear algebra gradient computations. This technical note provides a…

Numerical Analysis · Mathematics 2025-11-19 Jan Naumann

We develop a valuation-theoretic framework for studying tangent cones of torsion-free sheaves on algebraic varieties. To analyze these objects, we introduce a slope stability theory, including the Harder-Narasimhan filtrations, for finitely…

Algebraic Geometry · Mathematics 2026-02-03 Yohei Hada

A geometric derivation of $W_\infty$ Gravity based on Fedosov's deformation quantization of symplectic manifolds is presented. To lowest order in Planck's constant it agrees with Hull's geometric formulation of classical nonchiral…

High Energy Physics - Theory · Physics 2015-06-26 Carlos Castro

We construct a canonical stabilizer reduction $\widetilde{X}$ for any derived $1$-algebraic stack $X$ over $\mathbb{C}$ as a sequence of derived Kirwan blow-ups, under mild natural conditions that include the existence of a good moduli…

Algebraic Geometry · Mathematics 2023-03-28 Jeroen Hekking , David Rydh , Michail Savvas

Let $C\subset{\mathbb P}^{g-1}$ be a canonically embedded nonsingular nonhyperelliptic curve of genus $g$ and let $X\subset{\mathbb P}^{g-1}$ be a quadric containing $C$. Our main result states among other things that the Hilbert scheme of…

Algebraic Geometry · Mathematics 2017-02-03 Marco Boggi , Eduard Looijenga

In this paper, we investigate decentralized non-convex optimization with orthogonal constraints. Conventional algorithms for this setting require either manifold retractions or other types of projection to ensure feasibility, both of which…

Machine Learning · Computer Science 2024-12-10 Youbang Sun , Shixiang Chen , Alfredo Garcia , Shahin Shahrampour

It is well-known that DG-enhancements of D(QCoh(X)) are all equivalent to each other, see [23]. Here we present an explicit model which leads to applications in deformation theory. In particular, we shall describe three models for derived…

Algebraic Geometry · Mathematics 2018-08-16 Francesco Meazzini

Let $A = \Bbbk Q / I$ be the path algebra of any finite quiver $Q$ modulo any two-sided ideal $I$ of relations and let $R$ be any reduction system satisfying the diamond condition for $I$. We introduce an intrinsic notion of deformation of…

Quantum Algebra · Mathematics 2023-04-18 Severin Barmeier , Zhengfang Wang

This note aims to clarify the deep relationship between birational modifications of a variety and semiorthogonal decompositions of its derived category of coherent sheaves. The result is a conjecture on the existence and properties of…

Algebraic Geometry · Mathematics 2024-03-28 Daniel Halpern-Leistner

We study autoequivalences of the derived category of coherent sheaves of a variety arising from a variation of GIT quotient. We show that these automorphisms are spherical twists, and describe how they result from mutations of…

Algebraic Geometry · Mathematics 2016-08-16 Daniel Halpern-Leistner , Ian Shipman

Although the deformation of the Heisenberg algebra by a minimal length has become a central tool in quantum gravity phenomenology, it has never been rigorously obtained and is often derived using heuristic reasoning. In this study, we move…

General Relativity and Quantum Cosmology · Physics 2025-03-12 Naveed Ahmad Shah , S. S. Z. Ashraf , Aasiya Shaikh , Yas Yamin , P. K. Sahoo , Aaqid Bhat , Suhail Ahmad Lone , Mir Faizal , M. A. H. Ahsan

In this work we present different infinite dimensional algebras which appear as deformations of the asymptotic symmetry of the three-dimensional Chern-Simons gravity for the Maxwell algebra. We study rigidity and stability of the infinite…

High Energy Physics - Theory · Physics 2020-04-17 P. Concha , H. R. Safari

We analyse D-branes on orbifolds with discrete torsion, extending earlier results. We analyze certain Abelian orbifolds of the type C^3/ \Gamma, where \Gamma is given by Z_m x Z_n, for the most general choice of discrete torsion parameter.…

High Energy Physics - Theory · Physics 2009-10-31 David Berenstein , Robert G. Leigh

In this paper we apply a method devised in \cite{HartLarsSilv1D,LarsSilv1D} to the three-dimensional simple Lie algebra $\sll$. One of the main points of this deformation method is that the deformed algebra comes endowed with a canonical…

Rings and Algebras · Mathematics 2007-05-23 Daniel Larsson , Sergei D. Silvestrov