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Implicative hyper K -algebras

Mohammad Mehdi Zahedi, A. Borumand Saeid, R. A. Borzooei (2005)

Czechoslovak Mathematical Journal

In this note we first define the notions of (weak, strong) implicative hyper K -algebras. Then we show by examples that these notions are different. After that we state and prove some theorems which determine the relationship between these notions and (weak) hyper K -ideals. Also we obtain some relations between these notions and (weak) implicative hyper K -ideals. Finally, we study the implicative hyper K -algebras of order 3, in particular we obtain a relationship between the positive implicative...

Incidence structures of type ( p , n )

František Machala (2003)

Czechoslovak Mathematical Journal

Every incidence structure 𝒥 (understood as a triple of sets ( G , M , I ) , I ⊆ G × M ) admits for every positive integer p an incidence structure 𝒥 p = ( G p , M p , I p ) where G p ( M p ) consists of all independent p -element subsets in G ( M ) and I p is determined by some bijections. In the paper such incidence structures 𝒥 are investigated the 𝒥 p ’s of which have their incidence graphs of the simple join form. Some concrete illustrations are included with small sets G and M .

Incomparably continuable sets of semilattices

Jaroslav Ježek, Václav Slavík (2000)

Mathematica Bohemica

A finite set of finite semilattices is said to be incomparably continuable if it can be extended to an infinite set of pairwise incomparable (with respect to embeddability) finite semilattices. After giving some simple examples we show that the set consisting of the four-element Boolean algebra and the four-element fork is incomparably continuable.

Indecomposable matrices over a distributive lattice

Yi Jia Tan (2006)

Czechoslovak Mathematical Journal

In this paper, the concepts of indecomposable matrices and fully indecomposable matrices over a distributive lattice L are introduced, and some algebraic properties of them are obtained. Also, some characterizations of the set F n ( L ) of all n × n fully indecomposable matrices as a subsemigroup of the semigroup H n ( L ) of all n × n Hall matrices over the lattice L are given.

Independent axiom systems for nearlattices

João Araújo, Michael Kinyon (2011)

Czechoslovak Mathematical Journal

A nearlattice is a join semilattice such that every principal filter is a lattice with respect to the induced order. Hickman and later Chajda et al independently showed that nearlattices can be treated as varieties of algebras with a ternary operation satisfying certain axioms. Our main result is that the variety of nearlattices is 2 -based, and we exhibit an explicit system of two independent identities. We also show that the original axiom systems of Hickman as well as that of Chajda et al are...

Indexed annihilators in lattices

Ivan Chajda (1995)

Archivum Mathematicum

The concept of annihilator in lattice was introduced by M. Mandelker. Although annihilators have some properties common with ideals, the set of all annihilators in L need not be a lattice. We give the concept of indexed annihilator which generalizes it and we show the basic properties of the lattice of indexed annihilators. Moreover, distributive and modular lattices can be characterized by using of indexed annihilators.

Induced pseudoorders

Ivan Chajda, Miroslav Haviar (1991)

Acta Universitatis Palackianae Olomucensis. Facultas Rerum Naturalium. Mathematica

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