Uniform dimension of mappings (Preliminary communication)
Uniform sequences of -mappings
Uniformization of Topological Spaces with Small Inductive Dimension Zero.
Unique -closure for some -groups of rational valued functions
Usually, an abelian -group, even an archimedean -group, has a relatively large infinity of distinct -closures. Here, we find a reasonably large class with unique and perfectly describable -closure, the class of archimedean -groups with weak unit which are “-convex”. ( is the group of rationals.) Any is -convex and its unique -closure is the Alexandroff algebra of functions on defined from the clopen sets; this is sometimes .
Universal acyclic resolutions for arbitrary coefficient groups
We prove that for every compactum X and every integer n ≥ 2 there are a compactum Z of dimension ≤ n+1 and a surjective -map r: Z → X such that for every abelian group G and every integer k ≥ 2 such that we have and r is G-acyclic.
Universal analytic preorders arising from surjective functions
Examples are presented of Σ₁¹-universal preorders arising by requiring the existence of particular surjective functions. These are: the relation of epimorphism between countable graphs; the relation of being a continuous image (or a continuous image of some specific kind) for continua; the relation of being continuous open image for dendrites.
Universal completely regular dendrites
We define a dendrite which is universal in the class of all completely regular dendrites with order of points not greater than n. In particular, the dendrite is universal in the class of all completely regular dendrites. The construction starts with the standard universal dendrite of order n described by J. J. Charatonik.
Universal continua
Universal mappings and weakly confluent mappings
Universal maps of Cartesian products
Universal meager -sets in locally compact manifolds
In each manifold modeled on a finite or infinite dimensional cube , , we construct a meager -subset which is universal meager in the sense that for each meager subset there is a homeomorphism such that . We also prove that any two universal meager -sets in are ambiently homeomorphic.
Universal measure zero, large Hausdorff dimension, and nearly Lipschitz maps
We prove that each analytic set in ℝⁿ contains a universally null set of the same Hausdorff dimension and that each metric space contains a universally null set of Hausdorff dimension no less than the topological dimension of the space. Similar results also hold for universally meager sets. An essential part of the construction involves an analysis of Lipschitz-like mappings of separable metric spaces onto Cantor cubes and self-similar sets.
Universal rational spaces [Book]
Universal spaces for locally finite-dimensional and strongly countable-dimensional metrizable spaces
Universal spaces in the theory of transfinite dimension, I
R. Pol has shown that for every countable ordinal α, there exists a universal space for separable metrizable spaces X with ind X = α . We prove that for every countable limit ordinal λ, there is no universal space for separable metrizable spaces X with Ind X = λ. This implies that there is no universal space for compact metrizable spaces X with Ind X = λ. We also prove that there is no universal space for compact metrizable spaces X with ind X = λ.
Universal spaces in the theory of transfinite dimension, II
We construct a family of spaces with “nice” structure which is universal in the class of all compact metrizable spaces of large transfinite dimension , or, equivalently, of small transfinite dimension ; that is, the family consists of compact metrizable spaces whose transfinite dimension is , and every compact metrizable space with transfinite dimension is embeddable in a space of the family. We show that the least possible cardinality of such a universal family is equal to the least possible...
Universalmengen bezüglich der Lage im
Various kinds of local connectedness.
Wallman compactification and zero-dimensionality.
Waraszkiewicz spirals revisited
We study compactifications of a ray with remainder a simple closed curve. We give necessary and sufficient conditions for the existence of a bijective (resp. surjective) mapping between two such continua. Using those conditions we present a simple proof of the existence of an uncountable family of plane continua no one of which can be continuously mapped onto any other (the first such family, so called Waraszkiewicz's spirals, was created by Z. Waraszkiewicz in the 1930's).