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Tightness and π-character in centered spaces

Murray Bell (1999)

Colloquium Mathematicae

We continue an investigation into centered spaces, a generalization of dyadic spaces. The presence of large Cantor cubes in centered spaces is deduced from tightness considerations. It follows that for centered spaces X, πχ(X) = t(X), and if X has uncountable tightness, then t(X) = supκ : 2 κ ⊂ X. The relationships between 9 popular cardinal functions for the class of centered spaces are justified. An example is constructed which shows, unlike the dyadic and polyadic properties, that the centered...

Uncountably many wild knots whose cyclic branched covering are S3.

José María Montesinos-Amilibia (2003)

Revista Matemática Complutense

There is a disk in S3 whose interior is PL embedded and whose boundary has a tame Cantor set of locally wild points, such that the n-fold cyclic coverings of S3 branched over the boundary of the disk are all S3. An uncountable set of inequivalent wild knots with these properties is exhibited.

Universal reparametrization of a family of cycles : a new approach to meromorphic equivalence relations

David Mathieu (2000)

Annales de l'institut Fourier

We study analytic families of non-compact cycles, and prove there exists an analytic space of finite dimension, which gives a universal reparametrization of such a family, under some assumptions of regularity. Then we prove an analogous statement for meromorphic families of non-compact cycles. That is a new approach to Grauert’s results about meromorphic equivalence relations.

Weak-bases and D -spaces

Dennis K. Burke (2007)

Commentationes Mathematicae Universitatis Carolinae

It is shown that certain weak-base structures on a topological space give a D -space. This solves the question by A.V. Arhangel’skii of when quotient images of metric spaces are D -spaces. A related result about symmetrizable spaces also answers a question of Arhangel’skii. Theorem.Any symmetrizable space X is a D -space ( hereditarily ) . Hence, quotient mappings, with compact fibers, from metric spaces have a D -space image. What about quotient s -mappings? Arhangel’skii and Buzyakova have shown that...

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