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Displaying 881 – 900 of 975

Zone and double zone diagrams in abstract spaces

Daniel Reem, Simeon Reich (2009)

Colloquium Mathematicae

A zone diagram of order n is a relatively new concept which was first defined and studied by T. Asano, J. Matoušek and T. Tokuyama. It can be interpreted as a state of equilibrium between n mutually hostile kingdoms. Formally, it is a fixed point of a certain mapping. These authors considered the Euclidean plane with finitely many singleton-sites and proved the existence and uniqueness of zone diagrams there. In the present paper we generalize this concept in various ways. We consider general sites...

Zur Darstellung von Polynomen auf De Morgan Algebren

Dietmar W. Dorninger, Dietmar Schweigert (1980)

Czechoslovak Mathematical Journal

Zur Konstruktion vollständiger Polaritätsverbände.

Morike Kamara (1978)

Journal für die reine und angewandte Mathematik

$δ$ -ideals in pseudo-complemented distributive lattices

M. Sambasiva Rao (2012)

Archivum Mathematicum

The concept of $δ$ -ideals is introduced in a pseudo-complemented distributive lattice and some properties of these ideals are studied. Stone lattices are characterized in terms of $δ$ -ideals. A set of equivalent conditions is obtained to characterize a Boolean algebra in terms of $δ$ -ideals. Finally, some properties of $δ$ -ideals are studied with respect to homomorphisms and filter congruences.

$λ$ -lattices

Václav Snášel (1997)

Mathematica Bohemica

In this paper, we generalize the notion of supremum and infimum in a poset.

$ϱ$ -ideals in the lattice of semi $ϱ$ -ideals

Jaromír Duda (1981)

Archivum Mathematicum

$σ$ -elements in multiplicative lattices

C. Jayaram, E. W. Johnson (1998)

Czechoslovak Mathematical Journal

$Σ$ -isomorphic algebraic structures

Ivan Chajda, Petr Emanovský (1995)

Mathematica Bohemica

For an algebraic structure $= (A, F, R)$ or type and a set $Σ$ of open formulas of the first order language $L ()$ we introduce the concept of $Σ$ -closed subsets of . The set $ℂ_{Σ} ()$ of all $Σ$ -closed subsets forms a complete lattice. Algebraic structures , of type are called $Σ$ -isomorphic if $ℂ_{Σ} () ≅ ℂ_{Σ} ()$ . Examples of such $Σ$ -closed subsets are e.g. subalgebras of an algebra, ideals of a ring, ideals of a lattice, convex subsets of an ordered or quasiordered set etc. We study $Σ$ -isomorphic algebraic structures in dependence on the...