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Note on bi-Lipschitz embeddings into normed spaces

Jiří Matoušek (1992)

Commentationes Mathematicae Universitatis Carolinae

Let ( X , d ) , ( Y , ρ ) be metric spaces and f : X Y an injective mapping. We put f Lip = sup { ρ ( f ( x ) , f ( y ) ) / d ( x , y ) ; x , y X , x y } , and dist ( f ) = f Lip . f - 1 Lip (the distortion of the mapping f ). We investigate the minimum dimension N such that every n -point metric space can be embedded into the space N with a prescribed distortion D . We obtain that this is possible for N C ( log n ) 2 n 3 / D , where C is a suitable absolute constant. This improves a result of Johnson, Lindenstrauss and Schechtman [JLS87] (with a simpler proof). Related results for embeddability into p N are obtained by a similar method.

Note on dense covers in the category of locales

Jan Paseka (1994)

Commentationes Mathematicae Universitatis Carolinae

In this note we are going to study dense covers in the category of locales. We shall show that any product of finitely regular locales with some dense covering property has this property as well.

Note on the selection properties of set-valued semimartingales

Mariusz Michta (1996)

Discussiones Mathematicae, Differential Inclusions, Control and Optimization

Set-valued semimartingales are introduced as an extension of the notion of single-valued semimartingales. For such multivalued processes their semimartingale selection properties are investigated.

Notes on approximation in the Musielak-Orlicz sequence spaces of multifunctions

Andrzej Kasperski (1995)

Commentationes Mathematicae Universitatis Carolinae

We introduced the notion of ( 𝐗 , dist , 𝒱 ) -boundedness of a filtered family of operators in the Musielak-Orlicz sequence space X ϕ of multifunctions. This notion is used to get the convergence theorems for the families of 𝐗 -linear operators, 𝐗 -dist-sublinear operators and 𝐗 -dist-convex operators. Also, we prove that X ϕ is complete.

Notes on c f p -covers

Shou Lin, Peng Fei Yan (2003)

Commentationes Mathematicae Universitatis Carolinae

The main purpose of this paper is to establish general conditions under which T 2 -spaces are compact-covering images of metric spaces by using the concept of c f p -covers. We generalize a series of results on compact-covering open images and sequence-covering quotient images of metric spaces, and correct some mapping characterizations of g -metrizable spaces by compact-covering σ -maps and m s s c -maps.

Notes on Retracts of Coset Spaces

J. van Mill, G. J. Ridderbos (2005)

Bulletin of the Polish Academy of Sciences. Mathematics

We study retracts of coset spaces. We prove that in certain spaces the set of points that are contained in a component of dimension less than or equal to n, is a closed set. Using our techniques we are able to provide new examples of homogeneous spaces that are not coset spaces. We provide an example of a compact homogeneous space which is not a coset space. We further provide an example of a compact metrizable space which is a retract of a homogeneous compact space, but which is not a retract of...

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