We study ${{\mathbb{Z}}_{p}}$ actions on compact connected Riemann surfaces via their associated Eichler traces.We determine the set of possible Eichler traces and determine the relationship between 2 actions if they have the same trace.

The regular star-polyhedron $\left\{ 5,\,\frac{5}{2} \right\}$ is isomorphic to the abstract polyhedron $\left\{ 5,\,5|3 \right\}$, where the last entry “3” in its symbol denotes the size of a hole, given by the imposition of a certain extra relation on the group of the hyperbolic honeycomb $\left\{ 5,\,5 \right\}$. Here, analogous formulations are found for the groups of the regular 4-dimensional star-polytopes, and for those of the non-discrete regular 4-dimensional honeycombs. In all cases, the extra group relations to be imposed on the corresponding Coxeter groups are those arising from “deep holes”; thus the abstract description of $\left\{ 5,\,{{3}^{k}},\,\frac{5}{2} \right\}\,\text{is}\,\left\{ 5,\,{{3}^{k}},\,5|3 \right\}\,\text{for}\,k\,=\,1\,\text{or}\,\text{2}$. The non-discrete quasi-regular honeycombs in ${{\mathbb{E}}^{3}}$, on the other hand, are not determined in an analogous way.

A reverse iterated function system (r.i.f.s.) is defined to be a set of expansive maps $\left\{ {{T}_{1}},...,{{T}_{m}} \right\}$ on a discrete metric space $M$. An invariant set $F$ is defined to be a set satisfying $F\,=\,\bigcup _{j=1}^{m}\,{{T}_{j}}F$, and an invariant measure $\mu $ is defined to be a solution of $\mu \,=\,\sum{_{j=1}^{m}\,{{p}_{j}}\mu {}^\circ T_{j}^{-1}}$ for positive weights ${{p}_{j}}$. The structure and basic properties of such invariant sets and measures is described, and some examples are given. A blowup$\mathcal{F}$ of a self-similar set $F$ in ${{\mathbb{R}}^{n}}$ is defined to be the union of an increasing sequence of sets, each similar to $F$. We give a general construction of blowups, and show that under certain hypotheses a blowup is the sum set of $F$ with an invariant set for a r.i.f.s. Some examples of blowups of familiar fractals are described. If $\mu $ is an invariant measure on ${{\mathbb{Z}}^{+}}$ for a linear r.i.f.s., we describe the behavior of its analytic transform, the power series $\sum{_{n=0}^{\infty }\mu (n){{z}^{n}}}$ on the unit disc.

The aim of this paper is to study small Hankel operators $h$ on the Hardy space or on weighted Bergman spaces,where $\Omega $ is a finite type domain in ${{\mathbb{C}}^{2}}$ or a strictly pseudoconvex domain in ${{\mathbb{C}}^{n}}$. We give a sufficient condition on the symbol $f$ so that $h$ belongs to the Schatten class ${{S}_{p}}$, $1\,\le \,p\,<\,+\infty $.