Displaying similar documents to “A Note on a Theorem of Lion”

A Finite Axiomatization of Nondeterministic Regular Expressions

Flavio Corradini, Rocco De Nicola, Anna Labella (2010)

RAIRO - Theoretical Informatics and Applications

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An alternative (tree-based) semantics for a class of regular expressions is proposed that assigns a central rôle to the + operator and thus to nondeterminism and nondeterministic choice. For the new semantics a consistent and complete axiomatization is obtained from the original axiomatization of regular expressions by Salomaa and by Kozen by dropping the idempotence law for + and the distribution law of • over +.

Regular spaces of small extent are ω-resolvable

István Juhász, Lajos Soukup, Zoltán Szentmiklóssy (2015)

Fundamenta Mathematicae

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We improve some results of Pavlov and Filatova, concerning a problem of Malykhin, by showing that every regular space X that satisfies Δ(X) > e(X) is ω-resolvable. Here Δ(X), the dispersion character of X, is the smallest size of a non-empty open set in X, and e(X), the extent of X, is the supremum of the sizes of all closed-and-discrete subsets of X. In particular, regular Lindelöf spaces of uncountable dispersion character are ω-resolvable. We also prove that...

Protecting regular polygons.

Kemnitz, Arnfried, Szabó, László, Ujváry-Menyhárt, Zoltán (2000)

Beiträge zur Algebra und Geometrie

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