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A note on $G_delta$-sets and associated low separation axioms
In this paper we obtain some low separation axioms by utilizing the notions of $G_delta$-closure and $G_delta$-open sets.
BA - Obecná matematika
- 2005 •
- D
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D - Stať ve sborníku
Fractional coloring of planar graphs of girth five
A graph G is (a : b)-colorable if there exists an assignment of b-element subsets of {1, ..., a} to vertices of G such that sets assigned to adjacent vertices is an element of V(G), the graph G has a s...
Pure mathematics
- 2020 •
- Jimp •
- Link
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Jimp - Článek v periodiku v databázi Web of Science
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Characterization of Volterra spaces
In this paper we deal with a characterization of weak Volterra and Volterra spaces which is based on a general concept derived from a given nonempty system E of nonempty subsets of a topological space. It is shown that a system of all preopen G
BA - Obecná matematika
- 2013 •
- Jx •
- Link
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Jx - Nezařazeno - Článek v odborném periodiku (Jimp, Jsc a Jost)
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Gμ-covers and ω1-strongly compact cardinals
Lindelof numbers of sets Z subset of beta(lambda) lambda are examined in G delta-topologies (and in G mu- topologies). The results are in a close connection by means of extensions of weakly complete filters, by ta...
Pure mathematics
- 2023 •
- Jimp •
- Link
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Jimp - Článek v periodiku v databázi Web of Science
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Trichotomies for ideals of compact sets
We prove several trichotomy results for ideals of compact sets. Typically, we show that a ``sufficiently rich'' niversally Baire ideal is either F-sigma-delta-hard, or G-delta-sigma-hard, or else a sigma-ideal....
BA - Obecná matematika
- 2006 •
- Jx
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Jx - Nezařazeno - Článek v odborném periodiku (Jimp, Jsc a Jost)
A note on fragmentability and weak-g(delta) sets
In terms of fragmentability, we describe a new class of Banach spaces which may be c(0)-saturated but do not contain weak-G(delta) open bounded subsets. In particular, none of these spaces is isomorphic to a separable polyhedral spa...
BA - Obecná matematika
- 2012 •
- Jx •
- Link
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Jx - Nezařazeno - Článek v odborném periodiku (Jimp, Jsc a Jost)
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Group rings that are UJ rings
The set Delta(R) of all elements r of a ring R such that 1 + ru is a unit for every unit u extends the Jacobson radical J(R). R is a UJ ring (Delta U ring, respectively) if its units are of the form 1 +J(R) (1 + Delta
Pure mathematics
- 2021 •
- Jimp •
- Link
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Jimp - Článek v periodiku v databázi Web of Science
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Developable hyperspaces are metrizable
Developability of hyperspace topologies (locally finite,(bounded) Vietoris, Fell, respectively) on the nonempty closed sets is characterized. Submetrizability and having a G/delta-diagonal in the hyperspace setting...
BA - Obecná matematika
- 2003 •
- Jx
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Jx - Nezařazeno - Článek v odborném periodiku (Jimp, Jsc a Jost)
The biased odd cycle Game
In this paper we consider biased Maker-Breaker games played on the edge set of a given graph $G$. We prove that for every $delta>0$ and large enough $n$, there exists a constant $k$ for which if $delta(G)g...
BA - Obecná matematika
- 2013 •
- Jx •
- Link
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Jx - Nezařazeno - Článek v odborném periodiku (Jimp, Jsc a Jost)
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Adjoint functors and tree duality
A family T of digraphs is a complete set of obstructions for a digraph H if for an arbitrary digraph G the existence of a homomorphism from G to H is equivalent to the non-existence of a homomorphism from any member of T to...
BA - Obecná matematika
- 2009 •
- Jx
Rok uplatnění
Jx - Nezařazeno - Článek v odborném periodiku (Jimp, Jsc a Jost)
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