Abstract Diagonal (multiplication) operators acting between a particular class of countable inductive spectra Fréchet sequence spaces, called (LF)-spaces, are investigated. We prove results concerning boundedness, compactness, power and mean ergodicity. Furthermore, we determine when diagonal operator is Montel reflexive. analyze the in terms system weights defining spaces.

we show that in {bf zf} set theory without choice, the ultrafilter mbox{principle} ({bf up}) is equivalent to several compactness theorems for alexandroff discrete spaces and to rudin's lemma, a basic tool in topology and the theory of quasi-continuous domains. important consequences of rudin's lemma are various lift lemmas, saying that certain properties of posets are inherited by th...

This note aims at presenting the most general framework for a class U of random upper semicontinuous functions, namely random elements whose sample paths are upper semicontinuous (u.s.c.) functions, defined on some locally compact, Hausdorff and second countable base space, extending Matheron’s framework for random closed sets. It is shown that while the natural embedding process does not provi...

We prove that there is a coincidence index for the inclusion F (x) ∈ Φ(x) when Φ is convex-valued and satisfies certain compactness assumptions on countable sets. For F we assume only that it provides a coincidence index for single-valued finite-dimensional maps (e.g. F is a Vietoris map). For the special case F = id, the obtained fixed point index is defined if Φ is countably condensing; the a...

We study the model-theoretic aspects of a probability logic suited for talking about measure spaces. This nonclassical logic has a model theory rather different from that of classical predicate logic. In general, not every satisfiable set of sentences has a countable model, but we show that one can always build a model on the unit interval. Also, the probability logic under consideration is not...