Ergodic decomposition of probability laws

Summary The main results of the paper concern integral representations of convex sets of probability laws. Various types of simplices are introduced and characterized. Invariance with respect to Markovian operators plays a key rôle.     

The characteristic semigroup of a topological space

The main result of this paper is that two T₂ topological spaces are homeomorphic if and only if their corresponding characteristic semigroups are isomorphic. Certain classes of topological spaces are then characterized in terms of their characteristic semigroups.     

Ergodic decomposition of group actions on rooted trees

We prove a general result about the decomposition into ergodic components of group actions on boundaries of spherically homogeneous rooted trees. Namely, we identify the space of ergodic components with the boundary of the orbit tree associated with the action, and show that the canonical system of ergodic invariant probability measures coincides with the system of uniform measures on the boundaries of minimal invariant subtrees of the tree. Special attention is paid to the case of groups generated by finite automata. Few examples, including the lamplighter group, Sushchansky group, and so-called universal group, are considered in order to demonstrate applications of the theorem.     

Conservative markov processes on a topological space

A Markov operator preservingC(X) is known to induce a decomposition of the locally compact spaceX to conservative and dissipative parts. Two notions of ergodicity are defined and the existence of subprocesses is studied. A sufficient condition for the existence of a conservative subprocess is given, and then the process is assumed to be conservative. When it has no subprocesses, sufficient conditions for the existence of a σ-finite invariant measure are given, and are extended to continuous-time processes. When the invariant measure is unique, ratio limit theorems are proved for the discrete and continuous time processes. Examples show that some combinations of conservative processes are not necessarily conservative. This paper is a part of the authors’s Ph.D. thesis prepared at the Hebrew University under the direction of Professor S. R. Foguel, to whom the author is grateful for his helpful advice and kind encouragement.     

The topological structure of a certain Menger space

In this paper we will reconsider the topological structure of Menger probabilistic normed spaces (briefly PN-spaces) under the t-norm M. We will prove that this topology is compatible with the topology induced by a countable and separating family of semi-norms, and hence the well-known theorems of classical functional analysis (such as the principle of uniform boundedness, open mapping and closed graph theorems) are valid in this context also. We will meanwhile obtain a method by which one may construct easily a large class of PN-spaces. Finally, using this method, we see that a certain subspace of bounded linear operators between PN-spaces, i.e. the class of strongly bounded linear operators, has a natural PN structure.     

灰拓扑空间的连通性

研究灰拓扑空间的连通性,给出了灰拓扑空间连通定义和有关定理,并且研究了灰连通分支。     

Models of topological space geometries

We study a special class of models of R³-spaces in the sense of Betten. We single out some of the properties of these models, and use these properties as additional axioms for general R³-spaces. Then we investigate the consequences of these new axioms in general R³-spaces. We prove the continuity of the geometric operations which involve planes, and we characterize the planes in incidence geometric terms. Using these results, we study the topology of the space of planes and of line pencils, and we prove the continuity of collineations. The obtained results are applied to our concrete examples.     

Analytic and harmonic maps into a topological space

The relationship between the harmonicity and analyticity of a continuous map from the open unit disc to the underlying space of a real algebra is investigated.     

Ergodic theorems for hybrid sequences in a Hilbert space with applications

In this paper, we introduce the notion of generalized hybrid sequences, extending the notion of nonexpansive sequences introduced and studied in our previous work Djafari Rouhani (1981, 1990, 1990, 1997, 2002, 2004, 2002)  , , , , ,  and , and prove ergodic and convergence theorems for such sequences in a Hilbert space H$H$. Subsequently, we apply our results to prove new fixed point theorems for generalized hybrid mappings, first introduced in Kocourek et al. (2010)  [14], Takahashi and Takeuchi (2011)  [20], defined on arbitrary nonempty subsets of H$H$.     

On the Urysohn number of a topological space II

Abstract

Some variations of Arhangel'skii inequality ∣X∣ = 2^χ(X)L(X) for every Hausdorff space X [3], given in [2] and [6] are improved.     

A decomposition of continuity in ideal topological spaces

We introduce the notions of w-I-continuous and w*-I-continuous functions in ideal topological spaces and investigate some of their properties. Additionally, we obtain a decomposition of continuous functions.