Commutativeness of Fundamental Groups of Topological Groups
In this article we prove that fundamental groups based at the unit point of topological groups are commutative [11].
Compacidad Y Decibilidad De Logicas Monadicas Con Cuantificadores Cardinales.
Compact and ...-compact formulas in L..., ...
Compact covering mappings and cofinal families of compact subsets of a Borel set
Among other results we prove that the topological statement “Any compact covering mapping between two Π⁰₃ spaces is inductively perfect” is equivalent to the set-theoretical statement ""; and that the statement “Any compact covering mapping between two coanalytic spaces is inductively perfect” is equivalent to “Analytic Determinacy”. We also prove that these statements are connected to some regularity properties of coanalytic cofinal sets in (X), the hyperspace of all compact subsets of a Borel...
Compact covering mappings between Borel ѕpaces
Compact scattered spaces in forcing extensions
We consider the cardinal sequences of compact scattered spaces in models where CH is false. We describe a number of models of in which no such space can have ℵ₂ countable levels.
Compact sets without converging sequences in the random real model.
Compact spaces homeomorphic to a ray of ordinals
Compacta are maximally -resolvable
It is well-known that compacta (i.e. compact Hausdorff spaces) are maximally resolvable, that is every compactum contains many pairwise disjoint dense subsets, where denotes the minimum size of a non-empty open set in . The aim of this note is to prove the following analogous result: Every compactum contains many pairwise disjoint -dense subsets, where denotes the minimum size of a non-empty set in .
Compactifications of ℕ and Polishable subgroups of
We study homeomorphism groups of metrizable compactifications of ℕ. All of those groups can be represented as almost zero-dimensional Polishable subgroups of the group . As a corollary, we show that all Polish groups are continuous homomorphic images of almost zero-dimensional Polishable subgroups of . We prove a sufficient condition for these groups to be one-dimensional and also study their descriptive complexity. In the last section we associate with every Polishable ideal on ℕ a certain Polishable...
Compactness and chromatic number
Compactness and homogeneity of saturated structures. I.
Compactness and homogeneity of saturated structures. II.
Compactness and homomorphisms of algebraic structures
Compactness and Löwenheim-Skolem properties in categories of pre-institutions
The abstract model-theoretic concepts of compactness and Löwenheim-Skolem properties are investigated in the "softer" framework of pre-institutions [18]. Two compactness results are presented in this paper: a more informative reformulation of the compactness theorem for pre-institution transformations, and a theorem on natural equivalences with an abstract form of the first-order pre-institution. These results rely on notions of compact transformation, which are introduced as arrow-oriented generalizations...
Compactness in Metric Spaces
In this article, we mainly formalize in Mizar [2] the equivalence among a few compactness definitions of metric spaces, norm spaces, and the real line. In the first section, we formalized general topological properties of metric spaces. We discussed openness and closedness of subsets in metric spaces in terms of convergence of element sequences. In the second section, we firstly formalize the definition of sequentially compact, and then discuss the equivalence of compactness, countable compactness,...
Compactness of Powers of ω
We characterize exactly the compactness properties of the product of κ copies of the space ω with the discrete topology. The characterization involves uniform ultrafilters, infinitary languages, and the existence of nonstandard elements in elementary extensions. We also have results involving products of possibly uncountable regular cardinals.
Compactness=JEP in any logic
Comparing sets of the Baire space by means of general recursive operators
Comparing alternative definitions of Boolean-valued fuzzy sets