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A note on Sugihara algebras.

Josep M. Font, Gonzalo Rodríguez Pérez (1992)

Publicacions Matemàtiques

In [4] Blok and Pigozzi prove syntactically that RM, the propositional calculus also called R-Mingle, is algebraizable, and as a consequence there is a unique quasivariety (the so-called equivalent quasivariety semantics) associated to it. In [3] it is stated that this quasivariety is the variety of Sugihara algebras. Starting from this fact, in this paper we present an equational base for this variety obtained as a subvariety of the variety of R-algebras, found in [7] to be associated in the same...

A note on the computational complexity of hierarchical overlapping clustering

Mirko Křivánek (1985)

Aplikace matematiky

In this paper the computational complexity of the problem of the approximation of a given dissimilarity measure on a finite set X by a k -ultrametric on X and by a Robinson dissimilarity measure on X is investigared. It is shown that the underlying decision problems are NP-complete.

A note on the intersection ideal ℳ ∩ 𝒩

Tomasz Weiss (2013)

Commentationes Mathematicae Universitatis Carolinae

We prove among other theorems that it is consistent with Z F C that there exists a set X ⊆ 2 ω which is not meager additive, yet it satisfies the following property: for each F σ measure zero set F , X + F belongs to the intersection ideal ℳ ∩ 𝒩 .

A note on the structure of WUR Banach spaces

Spiros A. Argyros, Sophocles Mercourakis (2005)

Commentationes Mathematicae Universitatis Carolinae

We present an example of a Banach space E admitting an equivalent weakly uniformly rotund norm and such that there is no Φ : E → c 0 ( Γ ) , for any set Γ , linear, one-to-one and bounded. This answers a problem posed by Fabian, Godefroy, Hájek and Zizler. The space E is actually the dual space Y * of a space Y which is a subspace of a WCG space.

Currently displaying 261 – 280 of 724