We consider the dynamics of semi-hyperbolic semigroups generated by finitely many rational maps on the Riemann sphere. Assuming that the nice open set condition holds it is proved that there exists a geometric measure on the Julia set with exponent h equal to the Hausdorff dimension of the Julia set. Both h-dimensional Hausdorff and packing measures are finite and positive on the Julia set and ...

Given a closed connected Riemannian manifold M and a connected Riemannian manifold N , we study fiberwise, i.e. M × {z}, z ∈ N , volume decreasing diffeomorphisms on the product M × N . Our main theorem shows that in the presence of certain cohomological condition on M and N such diffeomorphisms must map a fiber diffeomorphically onto another fiber and are therefore fiberwise volume preserving....

In this article we prove the problem on isometric mappings of S posed by Th. M. Rassias. We prove that any map f : S → S, p ≥ n > 1, preserving two angles θ and mθ (mθ < π, m > 1) is an isometry. With the assumption of continuity we prove that any map f : S → S preserving an irrational angle is an isometry.

Given a closed connected Riemannian manifold M and a connected Riemannian manifold N , we study slice, i.e. M × {z}, z ∈ N , volume contracting diffeomorphisms on the product M ×N . Our main theorem shows that in the presence of certain cohomological condition on M and N such diffeomorphisms must map a slice diffeomorphically onto another slice and are therefore slice volume preserving. As a fi...

We consider the growth of some indicators of arithmetical complexity of rational orbits of (piecewise) affine maps of the plane, with rational parameters. The exponential growth rates are expressed by a set of exponents; one exponent describes the growth rate of the so-called logarithmic height of the points of an orbit, while the others describe the growth rate of the size of such points, meas...

S. Janson [Poset limits and exchangeable random posets, Combinatorica 31 (2011), 529–563] defined limits of finite posets in parallel to the emerging theory of limits of dense graphs. We prove that each poset limit can be represented as a kernel on the unit interval with the standard order, thus answering an open question of Janson. We provide two proofs: real-analytic and combinatorial. The co...

A category with finite products and finite coproducts is said to be distributive if the canonical map A×B + A×C → A× (B + C) is invertible for all objects A, B, and C. Given a distributive category D , we describe a universal functor D → Dex preserving finite products and finite coproducts, for which Dex is extensive; that is, for all objects A and B the functor Dex/A × Dex/B → Dex/(A + B) is a...