Recently, Shestakov-Umirbaev solved Nagata’s conjecture on an automorphism of a polynomial ring. To solve the conjecture, they defined notions called reductions of types I–IV for automorphisms of a polynomial ring. An automorphism admitting a reduction of type I was first found by Shestakov-Umirbaev. Using a computer, van den Essen–Makar-Limanov–Willems gave a family of such automorphisms. In t...

We present relations between growth, growth of diameters and the rate of vanishing of the spectral gap in Schreier graphs of automaton groups. In particular, we introduce a series of examples, called Hanoi Towers groups since they model the well known Hanoi Towers Problem, that illustrate some of the possible types of behavior. 1 Actions on rooted trees, automaton groups, and Hanoi Towers group...

This note gives an account of the algebraic construction of symbolic covers and representations of ergodic automorphisms of compact abelian groups. For expansive toral automorphisms this subject was initiated by A.M. Vershik.

Motions of the plane (shifts and rotations) correspond to automorphisms of the type I Arveson system of white noise. I prove that automorphisms corresponding to rotations cannot be extended to the type II Arveson system of Warren’s noise.

The conjugacy classes of the involutive automorphisms of the affine Kac-Moody algebras C (1) ℓ for ℓ ≥ 2 are determined using the matrix formulation of automorphisms of an affine Kac-Moody

Abstract We are interested in various aspects of spectral rigidity Cayley and Schreier graphs finitely generated groups. For each pair integers $d\geq 2$ $m \ge 1$, we consider an uncountable family groups automorphisms the rooted $d$-regular tree, which provide examples following interesting phenomena. $d=2$ any $m\geq 2$, get non-quasi-isometric with same Laplacian spectrum, a union two inter...