Displaying similar documents to “Compacta which are quasi-homeomorphic with a disk”

Borsuk's quasi-equivalence is not transitive

Andrzej Kadlof, Nikola Koceić Bilan, Nikica Uglešić (2007)

Fundamenta Mathematicae

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Borsuk's quasi-equivalence relation on the class of all compacta is considered. The open problem concerning transitivity of this relation is solved in the negative. Namely, three continua X, Y and Z lying in ℝ³ are constructed such that X is quasi-equivalent to Y and Y is quasi-equivalent to Z, while X is not quasi-equivalent to Z.

Versatile asymmetrical tight extensions

Olivier Olela Otafudu, Zechariah Mushaandja (2017)

Topological Algebra and its Applications

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We show that the image of a q-hyperconvex quasi-metric space under a retraction is q-hyperconvex. Furthermore, we establish that quasi-tightness and quasi-essentiality of an extension of a T0-quasi-metric space are equivalent.

Quasi-equivalence of compacta and spaces of components.

José M. Rodríguez Sanjurjo (1980)

Collectanea Mathematica

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Let X, Y be two compacta with Sh(X) = Sh (Y). Then, the spaces of components of X, Y are homeomorphic. This does not happen, in general, when X, Y are quasi-equivalent. In this paper we give a sufficient condition for the existence of a homeomorphism between the spaces of components of two quasi-equivalent compacta X, Y which maps each component in a quasi-equivalent component.

Quasi-linear maps

D. J. Grubb (2008)

Fundamenta Mathematicae

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A quasi-linear map from a continuous function space C(X) is one which is linear on each singly generated subalgebra. We show that the collection of quasi-linear functionals has a Banach space pre-dual with a natural order. We then investigate quasi-linear maps between two continuous function spaces, classifying them in terms of generalized image transformations.

On Quasi-Normality of Two-Sided Multiplication

Amouch, M. (2009)

Serdica Mathematical Journal

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2000 Mathematics Subject Classification: 47B47, 47B10, 47A30. In this note, we characterize quasi-normality of two-sided multiplication, restricted to a norm ideal and we extend this result, to an important class which contains all quasi-normal operators. Also we give some applications of this result.