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We make further observations on the features of Galois cohomology in the general model theoretic context. We make explicit the connection between forms of definable groups and first cohomology sets with coefficients in a suitable…

Logic · Mathematics 2021-05-28 Omar Leon Sanchez , David Meretzky , Anand Pillay

We present a Galois theory of parameterized linear differential equations where the Galois groups are linear differential algebraic groups, that is, groups of matrices whose entries are functions of the parameters and satisfy a set of…

Classical Analysis and ODEs · Mathematics 2007-05-23 Phyllis J. Cassidy , Michael F. Singer

Using the theory of group action, we first introduce the concept of the automorphism group of an exponential family or a graphical model, thus formalizing the general notion of symmetry of a probabilistic model. This automorphism group…

Artificial Intelligence · Computer Science 2012-07-24 Hung Hai Bui , Tuyen N. Huynh , Sebastian Riedel

Using the theory of group action, we first introduce the concept of the automorphism group of an exponential family or a graphical model, thus formalizing the general notion of symmetry of a probabilistic model. This automorphism group…

Artificial Intelligence · Computer Science 2013-09-27 Hung Bui , Tuyen Huynh , Sebastian Riedel

In this paper, we discuss a group-theoretical generalization of the well-known Gauss formula involving the functionthat counts the number of automorphisms of a finite group. This gives several characterizations of finite cyclic groups.

Group Theory · Mathematics 2022-12-20 Georgiana Fasolă , Marius Tărnăuceanu

We study model theory of fields with actions of a fixed finite group scheme. We prove the existence and simplicity of a model companion of the theory of such actions, which generalizes our previous results about truncated iterative…

Logic · Mathematics 2020-06-08 Daniel Max Hoffmann , Piotr Kowalski

We analyze definably compact groups in o-minimal expansions of ordered groups as a combination of semi-linear groups and groups definable in o-minimal expansions of real closed fields. The analysis involves structure theorems about their…

Logic · Mathematics 2012-02-28 Pantelis Eleftheriou , Ya'acov Peterzil

For $G$ an algebraic group definable over a model of $\operatorname{ACVF}$, or more generally a definable subgroup of an algebraic group, we study the stable completion $\widehat{G}$ of $G$, as introduced by Loeser and the second author.…

Logic · Mathematics 2021-01-08 Martin Hils , Ehud Hrushovski , Pierre Simon

We investigate the possible structures imposed on a finite group by its possession of an automorphism sending a large fraction of the group elements to their cubes, the philosophy being that this should force the group to be, in some sense,…

Group Theory · Mathematics 2007-10-24 Peter Hegarty

We study groups definable in existentially closed geometric fields with commuting derivations. Our main result is that such a group can be definably embedded in a group interpretable in the underlying geometric field. Compared to earlier…

Logic · Mathematics 2026-04-13 Anand Pillay , Françoise Point , Silvain Rideau-Kikuchi

In this article we introduce the notion of projective isomonodromy, which is a special type of monodromy evolving deformation of linear differential equations, based on the example of the Darboux-Halphen equation. We give an algebraic…

Classical Analysis and ODEs · Mathematics 2012-06-04 Claude Mitschi , Michael F. Singer

This paper is dedicated to the problem of infinite transitivity for algebraically generated automorphism groups of the affine plane. We provide a necessary and sufficient condition of infinite transitivity for a large family of subgroups…

Algebraic Geometry · Mathematics 2022-02-07 Alisa Chistopolskaya , Gregory Taroyan

Consider a smooth connected algebraic group $G$ acting on a normal projective variety $X$ with an open dense orbit. We show that Aut($X$) is a linear algebraic group if so is $G$; for an arbitrary $G$, the group of components of Aut($X$) is…

Algebraic Geometry · Mathematics 2019-11-21 Michel Brion

Humans develop certain cognitive abilities to recognize objects and their transformations without explicit supervision, highlighting the importance of unsupervised representation learning. A fundamental challenge in unsupervised…

Computer Vision and Pattern Recognition · Computer Science 2025-04-08 Kayato Nishitsunoi , Yoshiyuki Ohmura , Takayuki Komatsu , Yasuo Kuniyoshi

We prove automorphy lifting theorems for 2-dimensional Galois representations of absolute Galois groups of totally real fields when the residual representation is of "exceptional" type. This exceptional case is when we are in characteristic…

Number Theory · Mathematics 2015-03-13 Chandrashekhar B. Khare , Jack A. Thorne

In Remarks on Galois Cohomology and Definability [2], Pillay introduced definable Galois cohomology, a model-theoretic generalization of Galois cohomology. Let $M$ be an atomic and strongly $\omega$-homogeneous structure over a set of…

Logic · Mathematics 2026-01-12 David Meretzky

We prove that infinite definably simple locally finite groups of finite centraliser dimension are simple groups of Lie type over locally finite fields. Then, we identify conditions on automorphisms of a stable group that make it resemble…

Logic · Mathematics 2019-06-12 Ulla Karhumäki

In this paper we show, using Deligne-Lusztig theory and Kawanaka's theory of generalised Gelfand-Graev representations, that the decomposition matrix of the special linear and unitary group in non defining characteristic can be made…

Representation Theory · Mathematics 2017-06-30 David Denoncin

We study the semicontinuity of automorphism groups for perturbations of domains in complex space or in complex manifolds. We provide a new approach to the study of such results for domains having minimal boundary smoothness. The emphasis in…

Complex Variables · Mathematics 2011-09-15 Robert E. Greene , Kang-Tae Kim , Steven G. Krantz , AeRyeong Seo

Assume that $X$ and $Y$ are arithmetic schemes, i.e., integral schemes of finite types over $Spec(\mathbb{Z})$. Then $X$ is said to be quasi-galois closed over $Y$ if $X$ has a unique conjugate over $Y$ in some certain algebraically closed…

Algebraic Geometry · Mathematics 2009-10-10 Feng-Wen An