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Trinomial varieties are affine varieties given by a system of equations consisting of polynomials with three terms. Such varieties are total coordinate spaces of normal varieties with torus action of complexity one. For an affine variety…

Algebraic Geometry · Mathematics 2025-06-26 Mikhail Ignatev , Timofey Vilkin

For an arbitrary field K, let I be an ideal in the ring K[[x,y]] expressible as a polynomial in either the pair of ideals (x, y^4) and (x,y) or the pair (x,y^3) and (x^2, y). Let G be the group of automorphisms of K[[x,y]] sending the ideal…

Algebraic Geometry · Mathematics 2007-05-23 Heather Russell

The monography examines the problem of constructing a group of automorphisms of a graph. A graph automorphism is a mapping of a set of vertices onto itself that preserves adjacency. The set of such automorphisms forms a vertex group of a…

History and Overview · Mathematics 2024-07-18 Sergey Kurapov , Maxim Davidovsky

We show that the identity component of the group of diffeomorphisms of a closed oriented surface of positive genus admits many unbounded quasi-morphisms. As a corollary, we also deduce that this group is not uniformly perfect and its…

Geometric Topology · Mathematics 2020-03-31 Jonathan Bowden , Sebastian Hensel , Richard Webb

We prove that the tree almost automorphism groups admit exactly three commensurability classes of closed commensurated subgroups. Our proof utilizes an independently interesting characterization of subgroups of the tree almost automorphism…

Group Theory · Mathematics 2017-06-28 Adrien Le Boudec , Phillip Wesolek

We prove a new automorphy lifting theorem for l-adic representations where we impose a new condition at l, which we call `potential diagonalizability'. This result allows for `change of weight' and seems to be substantially more flexible…

Number Theory · Mathematics 2013-12-10 Thomas Barnet-Lamb , Toby Gee , David Geraghty , Richard Taylor

Toric subvarieties of projective space are classified up to projective automorphisms.

Representation Theory · Mathematics 2019-09-11 Friedrich Knop , Rainer Sinn

We obtain analogues of classical results on automorphism groups of holomorphic fiber bundles, in the setting of group schemes. Also, we establish a lifting property of the connected automorphism group, for torsors under abelian varieties.…

Algebraic Geometry · Mathematics 2011-06-30 Michel Brion

We give a combinatorial criterion that implies both the non-strong relative hyperbolicity and the one-endedness of a finitely generated group. We use this to show that many important classes of groups do not admit a strong relatively…

Geometric Topology · Mathematics 2007-05-23 James W. Anderson , Javier Aramayona , Kenneth J. Shackleton

A survey article that presents some recent algebraic and model-theoretic results on the automorphism groups of relatively free groups of infinite rank. The topics include topological aspects, generating sets, descripition of automorpisms…

Group Theory · Mathematics 2008-07-29 Vladimir Tolstykh

Nikulin-type orbifolds are certain singular 4-dimensional irreducible holomorphic symplectic varieties. We show that the monodromy group of Nikulin-type orbifolds is maximal and classify finite order symplectic automorphisms up to…

Algebraic Geometry · Mathematics 2026-04-21 Simon Brandhorst , Grégoire Menet , Stevell Muller

In the present work we obtain rigidity results analysing the set of regular points, in the sense of Oseledec's Theorem. It is presented a study on the possibility of an Anosov diffeomorphisms having all Lyapunov exponents defined…

Dynamical Systems · Mathematics 2022-03-18 Fernando Micena , Rafael de la Llave

We prove a topological rigidity result for simple, thick, hyperbolic P-manifolds of dimension 2: isomorphism of the fundamental groups implies homeomorphism of the P-manifolds. An immediate application is a diagram rigidity theorem for…

Group Theory · Mathematics 2007-05-23 J. -F. Lafont

This article initiates a geometric study of the automorphism groups of general graph products of groups, and investigates the algebraic and geometric structure of automorphism groups of cyclic product of groups. For a cyclic product of at…

Group Theory · Mathematics 2018-03-21 Anthony Genevois , Alexandre Martin

We introduce a torsor-theoretic obstruction to equivariant unirationality and show that it is also sufficient for actions of finite groups on toric varieties arising from automorphisms of the torus.

Algebraic Geometry · Mathematics 2025-06-10 Andrew Kresch , Yuri Tschinkel

In this paper we use formal group rings to construct an algebraic model of the $T$-equivariant oriented cohomology of smooth toric varieties. Then we compare our model with known results of equivariant cohomology of toric varieties to…

Algebraic Geometry · Mathematics 2015-03-27 Wanshun Wong

In this note we show that the nonnegative part of a proper complex toric variety has the homeomorphism type of a sphere, and consequently that the nonnegative part has a natural structure of a cell complex. This extends previous results of…

Algebraic Geometry · Mathematics 2025-04-21 Mike Roth

We address a natural question in noncommutative geometry, namely the rigidity observed in many examples, whereby noncommutative spaces (or equivalently their coordinate algebras) have very few automorphisms by comparison with their…

Rings and Algebras · Mathematics 2022-04-29 Nicholas Cooney , Jan E. Grabowski

In this paper we construct two groupoids from morphisms of groupoids, with one from a categorical viewpoint and the other from a geometric viewpoint. We show that for each pair of groupoids, the two kinds of groupoids of morphisms are…

Category Theory · Mathematics 2019-08-16 Bohui Chen , Cheng-Yong Du , Rui Wang

We investigate toric varieties defined by arrangements of hyperplanes and call them strongly symmetric. The smoothness of such a toric variety translates to the fact that the arrangement is crystallographic. As a result, we obtain a…

Algebraic Geometry · Mathematics 2015-01-14 M. Cuntz , Y. Ren , G. Trautmann