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## Geometrical Description of Orbits of Automorphism Group of Affine Toric Varieties

Moscow University Mathematics Bulletin. 2019. Vol. 74. No. 5. P. 209-211.

Let *X* be an affine toric variety over an algebraically closed field of characteristic zero. Orbits of connected component of identity of automorphism group in terms of dimensions of tangent spaces of the variety *X* are described. A formula to calculate these dimensions is presented.

Chebochko N., Kuznetsov M., Communications in Algebra 2017 Vol. 45 No. 7 P. 2969-2977

All classes of integrable cocycles in H2(L,L) are obtained for Lie algebra of type G2 over an algebraically closed field of characteristic 2. It is proved that there exist only two orbits of classes of integrable cocycles with respect to automorphism group. The global deformation is shown to exist for any nontrivial class of integrable cocycles. ...

Added: October 10, 2017

Perepechko A., Функциональный анализ и его приложения 2013 Т. 47 № 4 С. 45-52

We prove that the action of the special automorphism group on affine cones over del Pezzo surfaces of degree 4 and 5 is infinitely transitive. ...

Added: September 26, 2019

Shafarevich A., Results in Mathematics 2021 Vol. 76 No. 3 Article 145

Let KK be an algebraically closed field of characteristic zero and GaGa be the additive group of KK. We say that an irreducible algebraic variety X of dimension n over the field KK admits an additive action if there is a regular action of the group Gna=Ga×⋯×GaGan=Ga×⋯×Ga (n times) on X with an open orbit. In this paper we find all projective toric hypersurfaces admitting additive action. ...

Added: September 10, 2021

Perepechko A., Michałek M., Süß H., Mathematische Zeitschrift 2018 Vol. 290 No. 3-4 P. 1457-1478

We provide a new criterion for flexibility of affine cones over varieties covered by flexible affine varieties. We apply this criterion to prove flexibility of affine cones over secant varieties of Segre–Veronese embeddings and over certain Fano threefolds. We further prove flexibility of total coordinate spaces of Cox rings of del Pezzo surfaces. ...

Added: September 26, 2019

Kurnosov N., Ясинский Е., Automorphisms of hyperkähler manifolds and groups acting on CAT(0) spaces / Cornell University. Series arXiv "math". 2018.

We study groups of bimeromorphic and biholomorphic automorphisms of projective hyperkähler manifolds. Using an action of these groups on some non-positively curved space, we deduce many of their properties, including finite presentation, strong form of Tits' alternative and some structural results about groups consisting of transformations with infinite order. ...

Added: December 2, 2018

Shramov K., Automorphisms of cubic surfaces without points / Cornell University. Series arXiv "math". 2020.

We classify finite groups acting by birational transformations of a non-trivial Severi--Brauer surface over a field of characteristc zero that are not conjugate to subgroups of the automorphism group. Also, we show that the automorphism group of a smooth cubic surface over a field K of characteristic zero that has no K-points is abelian, and find a sharp ...

Added: August 19, 2020

Popov V., Embeddings of groups Aut(F_n) into automorphism groups of algebraic varieties / Cornell University. Series math "arxiv.org". 2021. No. 2106.02072.

For each integer n>0, we construct a series of irreducible algebraic varieties X, for which the automorphism group Aut(X) contains as a subgroup the automorphism group Aut(F_n) of a free group F_n of rank n. For n > 1, such groups Aut(X) are nonamenable, and for n > 2, they are nonlinear and contain the ...

Added: June 7, 2021

Prokhorov Y., Shramov K., Automorphism groups of Inoue and Kodaira surfaces / Cornell University. Series arXiv "math". 2018.

We prove that automorphism groups of Inoue and primary Kodaira surfaces are Jordan. ...

Added: June 8, 2019

Ye L., Faisceau Automorphe Unipotent pour G2,Nombres de Franel, et Stratification deThom-Boardman / Cornell University. Series math "arxiv.org". 2020.

Thesis of the author. ...

Added: December 16, 2019

Shramov K., European Journal of Mathematics 2019

We show that automorphism groups of Hopf and Kodaira surfaces have unbounded
finite subgroups. For elliptic fibrations on Hopf, Kodaira, bielliptic, and K3 surfaces,
we make some observations on finite groups acting along the fibers and on the base
of such a fibration. ...

Added: December 11, 2019

Cheltsov I., Prokhorov Y., Algebraic Geometry 2021 Vol. 8 No. 3 P. 319-357

We classify del Pezzo surfaces with Du Val singularities that have infinite automorphism groups, and describe the connected components of their automorphisms groups. ...

Added: September 7, 2021

Perepechko A., Математические заметки 2021 Т. 110 № 5 С. 744-750

Affine algebraic surfaces of Markov type of the form
x^2 + y^2 + z^2 − xyz = c
are studied. Their automorphism groups are found. ...

Added: October 12, 2021

Kuyumzhiyan K., Proceedings of the American Mathematical Society 2020 No. 148 P. 3723-3731

We prove the conjecture of Berest-Eshmatov-Eshmatov by showing that the group of automorphisms of a product of Calogero-Moser spaces C_n_i, where the n_i are pairwise distinct, acts m-transitively for each m. ...

Added: August 18, 2020

Zhukova N., Шеина К., Труды Математического центра им. Н.И. Лобачевского 2014 Т. 50 С. 74-76

We investigate Cartan foliations covered by fibrations. We obtain a sufficient condition for the full
basic automorphism group of a complete Cartan foliation covered by fibration to admit a
unique (finite-dimensional) Lie group structure in the category of
Cartan foliations. The explicit new formula for determining its basic automorphism
Lie group is given. Examples of computing the full basic ...

Added: November 12, 2014

Osipov D., Математические заметки 2015 Т. 98 № 1 С. 152-155

В статье вычисляется группа автоморфизмов дискретной группы Гейзенберга. ...

Added: January 26, 2018

Shramov K., Przyjalkowski V., Proceedings of the Steklov Institute of Mathematics 2019 Vol. 307 P. 198-209

We show that smooth well-formed weighted complete intersections have finite automorphism groups, with several obvious exceptions. ...

Added: August 12, 2020

Galkin S., Belmans P., Mukhopadhyay S., Experimental Mathematics 2019

We give the first examples of smooth Fano and Calabi–Yau varieties violating the (narrow) canonical strip hypothesis, which concerns the location of the roots of Hilbert polynomials of polarized varieties. They are given by moduli spaces of rank 2 bundles with fixed odd-degree determinant on curves of sufficiently high genus, hence our Fano examples have ...

Added: October 4, 2019

Avilov A., Математические заметки 2020 Т. 107 № 1 С. 3-10

The forms of the Segre cubic over non-algebraically closed fields, their automorphisms groups, and equivariant birational rigidity are studied. In particular, it is shown that all forms of the Segre cubic over any field have a point and are cubic hypersurfaces. ...

Added: May 11, 2020

Zhukova N., Moscow Mathematical Journal 2018

We introduce a category of rigid geometries on singular spaces which
are leaf spaces of foliations and are considered as leaf manifolds. We
single out a special category F_0 of leaf manifolds containing the orbifold
category as a full subcategory. Objects of F_0 may have non-Hausdorff
topology unlike the orbifolds. The topology of some objects of F_0 does
not satisfy ...

Added: April 2, 2018

Przyjalkowski V., Shramov K., Математический сборник 2021 Т. 212 № 3 С. 112-127

Показано, что действие любой редуктивной подгруппы в группе автоморфизмов квазигладкого хорошо сформированного взвешенного полного пересечения размерности не меньше 3 индуцировано действием подгруппы в группе автоморфизмов объемлющего взвешенного проективного пространства. Приведены примеры, показывающие, что группа автоморфизмов квазигладкого хорошо сформированного взвешенного полного пересечения Фано может быть бесконечной и даже нередуктивной. ...

Added: March 5, 2021

Sheina K., Basic automorphism of Cartan foliations covered by fibrations / Cornell University. Series arXiv "math". 2020. No. 04348v1.

The basic automorphism group of a Cartan foliation (M, F) is the quotient group of the automorphism group of (M, F) by the normal subgroup, which preserves every leaf invariant. For Cartan foliations covered by fibrations, we find sufficient conditions for the existence of a structure of a finite-dimensional Lie group in their basic automorphism groups. Estimates ...

Added: December 9, 2020

Tokyo: American Mathematical Society, World Scientific, 2017

Preface
The workshop “Algebraic Varieties and Automorphism Groups” was held at the Research Institute of Mathematical Sciences (RIMS), Kyoto University during July 7-11, 2014. There were over eighty participants including twenty people from overseas Canada, France, Germany, India, Korea, Poland, Russia, Singapore, Switzerland, and USA.
Recently, there have been remarkable developments in algebraic geometry and related fields, ...

Added: July 12, 2017

Avilov A., European Journal of Mathematics 2018 Vol. 4 No. 3 P. 761-777

We classify three-dimensional singular cubic hypersurfaces with an action of a finite group G, which are not G-rational and have no birational structure of G-Mori fiber space with the base of positive dimension. Also we prove the 𝔄5A5-birational superrigidity of the Segre cubic. ...

Added: September 16, 2018

Popov V., Proceedings of the Steklov Institute of Mathematics 2016 Vol. 292 P. 209-223

For every algebraically closed field k of characteristic different from 2, we prove
the following: (1) Finite-dimensional (not necessarily associative) k-algebras of general type
of a fixed dimension, considered up to isomorphism, are parametrized by the values of a tuple
of algebraically independent (over k) rational functions of the structure constants. (2) There
exists an “algebraic normal form” to ...

Added: March 29, 2016