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L vector spaces and L fields
We construct in ZFC (the Zermelo-Fraenkel system with choice) an L topological vector space—a topological vector space that is an L space—and an L...
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Application of selection principles in the study of the properties of function spaces
For a Tychonoff space X , we denote by C p ( X ) the space of all real-valued continuous functions on X with the topology of pointwise convergence.
In...
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On constructions with 2-cardinals
We propose develo** the theory of consequences of morasses relevant in mathematical applications in the language alternative to the usual one,...
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Extendability to summable ideals
We continue our work on the ideal version of the Lévy–Steinitz theorem on conditionally convergent series of vectors. In particular, we prove that...
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Menger remainders of topological groups
In this paper we discuss what kind of constrains combinatorial covering properties of Menger, Scheepers, and Hurewicz impose on remainders of...
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Two point sets with additional properties
A subset of the plane is called a two point set if it intersects any line in exactly two points. We give constructions of two point sets possessing...
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Flow Graphs: Analysis with Near Sets
This paper introduces a framework for flow graphs induced by perceptual systems as well as analysis of such graphs using near set theory. A...
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Why the Logical Hexagon?
The logical hexagon (or hexagon of opposition) is a strange, yet beautiful, highly symmetrical mathematical figure, mysteriously intertwining...
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Cardinal coefficients associated to certain orders on ideals
We study cardinal invariants connected to certain classical orderings on the family of ideals on ω . We give topological and analytic...
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On Union Ultrafilters
We present some new results on union ultrafilters. We characterize stability for union ultrafilters and, as the main result, we construct a new kind...
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Small universal families for graphs omitting cliques without GCH
When no single universal model for a set of structures exists at a given cardinal, then one may ask in which models of set theory does there exist a...
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Brown Representability Test Problems in Locally Grothendieck Categories
Open questions concerning Brown representability have recently led Rosický and Muro to formulate two test problems for Grothendieck categories. We...
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Equivalent complete norms and positivity
In the first part of the article we characterize automatic continuity of positive operators. As a corollary we consider complete norms for which a...
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Modellierung vager und ungenauer Informationen
The use of linguistic terms like “profitable” or “well-priced” is common in business administration. However, they cannot be quantified with...
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Filtrations for the Roots of Ext
We survey the set–theoretic methods of module theory that make it possible to equip roots of the contravariant Ext functor with filtrations built...
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The depth of ultraproducts of Boolean algebras
We show that if μ is a compact cardinal then the depth of ultraproducts of less than μ many Boolean algebras is at most μ plus the ultraproduct of...