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Producto, convexificación y completación de espacios métricos generalizados y probabilísticos.

Claudi Alsina (1978)

Stochastica

En 1967 E. Trillas introdujo la noción de espacio métrico generalizado, al considerar métricas abstractas valoradas en semigrupos ordenados, unificando con este punto de vista algebraico-reticular las estructuras métricas reales de M. Fréchet ([5]) y los espacios métricos probabilísticos de K. Menger ([6]) (así como los espacios Booleanos de Blumenthal ([4]) y las métricas naturales definidas en grupos ordenados). En el presente artículo se abordan los problemas de la topología del orden, del producto,...

Pseudoradial Spaces: Finite Products and an Example From CH

Simon, Petr, Tironi, Gino (1998)

Serdica Mathematical Journal

∗ The first named author’s research was partially supported by GAUK grant no. 350, partially by the Italian CNR. Both supports are gratefully acknowledged. The second author was supported by funds of Italian Ministery of University and by funds of the University of Trieste (40% and 60%).Aiming to solve some open problems concerning pseudoradial spaces, we shall present the following: Assuming CH, there are two semiradial spaces without semi-radial product. A new property of pseudoradial spaces...

Structure resolvability

Rolando Jimenez, Viacheslav I. Malykhin (1998)

Commentationes Mathematicae Universitatis Carolinae

We introduce the general notion of structure resolvability and structure irresolvability, generalizing the usual concepts of resolvability and irresolvability.

The characterizations of upper approximation operators based on special coverings

Pei Wang, Qingguo Li (2017)

Open Mathematics

In this paper, we discuss the approximation operators [...] apr¯NS a p r ¯ N S and [...] apr¯S a p r ¯ S which are based on NS(U) and S. We not only obtain some properties of NS(U) and S, but also give examples to show some special properties. We also study sufficient and necessary conditions when they become closure operators. In addition, we give general and topological characterizations of the covering for two types of covering-based upper approximation operators being closure operators.

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