A remark on the orbit spaces under multiplicative group actions
A remarkable contraction of semisimple Lie algebras
Recently, E.Feigin introduced a very interesting contraction of a semisimple Lie algebra (see arXiv:1007.0646 and arXiv:1101.1898). We prove that these non-reductive Lie algebras retain good invariant-theoretic properties of . For instance, the algebras of invariants of both adjoint and coadjoint representations of are free, and also the enveloping algebra of is a free module over its centre.
A restriction theorem and the Poincare series for U-invariants.
A Smooth Four-Dimensional G-Hilbert Scheme
2000 Mathematics Subject Classification: 14C05, 14L30, 14E15, 14J35.When the cyclic group G of order 15 acts with some specific weights on affine four-dimensional space, the G-Hilbert scheme is a crepant resolution of the quotient A^4 / G. We give an explicit description of this resolution using G-graphs.
A Very Simple Proof of Bott's Theorem.
Abelian group actions on algebraic varieties with one fixed point.
Abelian Varieties, l-adic Representations and Lie Algebras.
Action du groupe additif
Actions of group schemes (I)
Actions of parabolic subgroups in GL_n on unipotent normal subgroups and quasi-hereditary algebras
Let R be a parabolic subgroup in . It acts on its unipotent radical and on any unipotent normal subgroup U via conjugation. Let Λ be the path algebra of a directed Dynkin quiver of type with t vertices and B a subbimodule of the radical of Λ viewed as a Λ-bimodule. Each parabolic subgroup R is the group of automorphisms of an algebra Λ(d), which is Morita equivalent to Λ. The action of R on U can be described using matrices over the bimodule B. The advantage of this description is that each...
Affine lines on logarithmic Q-homology planes.
AK-invariant, some conjectures, examples and counterexamples
In my talk I am going to remind you what is the AK-invariant and give examples of its usefulness. I shall also discuss basic conjectures about this invariant and some positive and negative results related to these conjectures.
Algebraic automorphisms of smooth affine surfaces.
Algebraic leaves of algebraic foliations over number fields
We prove an algebraicity criterion for leaves of algebraic foliations defined over number fields. Namely, consider a number field embedded in , a smooth algebraic variety over , equipped with a rational point , and an algebraic subbundle of the its tangent bundle , defined over . Assume moreover that the vector bundle is involutive, i.e., closed under Lie bracket. Then it defines an holomorphic foliation of the analytic manifold , and one may consider its leaf through . We prove...
Algebraic Legendrian varieties [Book]
Algebraic SL(2)-actions: deformations of infinite isotropy subgroups
Algebraic zip data.
Algebras with finitely generated invariant subalgebras
We classify all finitely generated integral algebras with a rational action of a reductive group such that any invariant subalgebra is finitely generated. Some results on affine embeddings of homogeneous spaces are also given.
Almost proper GIT-stacks and discriminant avoidance.
An Equivariant Lefschetz Formula for Finite Reductive Groups.