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A Note on Differentiability of Lipschitz Maps

Rafał Górak (2010)

Bulletin of the Polish Academy of Sciences. Mathematics

We show that every Lipschitz map defined on an open subset of the Banach space C(K), where K is a scattered compactum, with values in a Banach space with the Radon-Nikodym property, has a point of Fréchet differentiability. This is a strengthening of the result of Lindenstrauss and Preiss who proved that for countable compacta. As a consequence of the above and a result of Arvanitakis we prove that Lipschitz functions on certain function spaces are Gâteaux differentiable.

A note on discrete sets

Santi Spadaro (2009)

Commentationes Mathematicae Universitatis Carolinae

We give several partial positive answers to a question of Juhász and Szentmiklóssy regarding the minimum number of discrete sets required to cover a compact space. We study the relationship between the size of discrete sets, free sequences and their closures with the cardinality of a Hausdorff space, improving known results in the literature.

A note on D-spaces

Shou Lin (2006)

Commentationes Mathematicae Universitatis Carolinae

Every semi-stratifiable space or strong Σ -space has a σ -cushioned (mod k )-network. In this paper it is showed that every space with a σ -cushioned (mod k )-network is a D-space, which is a common generalization of some results about D-spaces.

A note on f.p.p. and f * . p . p .

Hisao Kato (1993)

Colloquium Mathematicae

In [3], Kinoshita defined the notion of f * . p . p . and he proved that each compact AR has f * . p . p . In [4], Yonezawa gave some examples of not locally connected continua with f.p.p., but without f * . p . p . In general, for each n=1,2,..., there is an n-dimensional continuum X n with f.p.p., but without f * . p . p . such that X n is locally (n-2)-connected (see [4, Addendum]). In this note, we show that for each n-dimensional continuum X which is locally (n-1)-connected, X has f.p.p. if and only if X has f * . p . p .

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