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Absolute end points of irreducible continua

Janusz Jerzy Charatonik (1993)

Mathematica Bohemica

A concept of an absolute end point introduced and studied by Ira Rosenholtz for arc-like continua is extended in the paper to be applied arbitrary irreducible continua. Some interrelations are studied between end points, absolute end points and points at which a given irreducible continuum is smooth.

Absolute n-fold hyperspace suspensions

Sergio Macías, Sam B. Nadler, Jr. (2006)

Colloquium Mathematicae

The notion of an absolute n-fold hyperspace suspension is introduced. It is proved that these hyperspaces are unicoherent Peano continua and are dimensionally homogeneous. It is shown that the 2-sphere is the only finite-dimensional absolute 1-fold hyperspace suspension. Furthermore, it is shown that there are only two possible finite-dimensional absolute n-fold hyperspace suspensions for each n ≥ 3 and none when n = 2. Finally, it is shown that infinite-dimensional absolute n-fold hyperspace suspensions...

Absolutely terminal continua and confluent mappings

Janusz Jerzy Charatonik (1991)

Commentationes Mathematicae Universitatis Carolinae

Interrelations between three concepts of terminal continua and their behaviour, when the underlying continuum is confluently mapped, are studied.

Addition theorems and D -spaces

Aleksander V. Arhangel'skii, Raushan Z. Buzyakova (2002)

Commentationes Mathematicae Universitatis Carolinae

It is proved that if a regular space X is the union of a finite family of metrizable subspaces then X is a D -space in the sense of E. van Douwen. It follows that if a regular space X of countable extent is the union of a finite collection of metrizable subspaces then X is Lindelöf. The proofs are based on a principal result of this paper: every space with a point-countable base is a D -space. Some other new results on the properties of spaces which are unions of a finite collection of nice subspaces...

Algebraic properties of quasi-finite complexes

M. Cencelj, J. Dydak, J. Smrekar, A. Vavpetič, Ž. Virk (2007)

Fundamenta Mathematicae

A countable CW complex K is quasi-finite (as defined by A. Karasev) if for every finite subcomplex M of K there is a finite subcomplex e(M) such that any map f: A → M, where A is closed in a separable metric space X satisfying XτK, has an extension g: X → e(M). Levin's results imply that none of the Eilenberg-MacLane spaces K(G,2) is quasi-finite if G ≠ 0. In this paper we discuss quasi-finiteness of all Eilenberg-MacLane spaces. More generally, we deal with CW complexes with finitely many...

An approach to covering dimensions

Miroslav Katětov (1995)

Commentationes Mathematicae Universitatis Carolinae

Using certain ideas connected with the entropy theory, several kinds of dimensions are introduced for arbitrary topological spaces. Their properties are examined, in particular, for normal spaces and quasi-discrete ones. One of the considered dimensions coincides, on these spaces, with the Čech-Lebesgue dimension and the height dimension of posets, respectively.

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