Nilpotent endomorphisms of expansive group actions

Rational Endomorphisms of a Nilpotent Group

Let G be a group. An endomorphism φ of G is called rational if there exist a1, . . . , ar ∈ G and h1, . . . , hr ∈ Z, such that φ(x) = (xa1)1 . . . (xar)r for all x ∈ G. We denote by Endr(G) the group of invertible rational endomorphisms of G. In this note, we prove that G is nilpotent of class c (c ≥ 3) if and only if Endr(G) is nilpotent of class c − 1. Mathematics Subject Classification: 20E...

Nilpotent Families of Endomorphisms of ...

Homoclinic Group, Ie Group, and Expansive Algebraic Actions

We give algebraic characterizations for expansiveness of algebraic actions of countable groups. The notion of p-expansiveness is introduced for algebraic actions, and we show that for countable amenable groups, a finitely presented algebraic action is 1-expansive exactly when it has finite entropy. We also study the local entropy theory for actions of countable amenable groups on compact groups...

Nilpotent Orbits, Normality, and Hamiltonian Group Actions

Let M be a G-covering of a nilpotent orbit in 0 where G isa complex semisimple Lie group and g = Lie(G). We prove that under Poisson bracket the space R[2] of homogeneous functions on M of degree 2 is the unique maximal semisimple Lie subalgebra of R = R{M) containing g . The action of g' ~ R[2] exponentiates to an action of the corresponding Lie group G' on a G'-cover M' of a nilpotent orbit i...

On the structure of nilpotent endomorphisms and applications

The nilpotent endomorphisms over a finite free module over a domain with principal ideal are characterized. One may apply these results to the study of the maximal Cohen-Macaulay modules over the ring R := A[[x]]/(x), n ≥ 2, where A is a DVR. Subject Classification: 15A21, 13C14.