Distributivity and wellfounded semilattices.
Duality for Hilbert algebras with supremum: An application
We modify slightly the definition of -partial functions given by Celani and Montangie (2012); these partial functions are the morphisms in the category of -space and this category is the dual category of the category with objects the Hilbert algebras with supremum and morphisms, the algebraic homomorphisms. As an application we show that finite pure Hilbert algebras with supremum are determined by the monoid of their endomorphisms.
Embedding in globals of finite semilattices
Embedding of semilattices into distributive lattices
Endomorphism semigroups of Brouwerian semilattices.
Filters and annihilators in implication algebras
Finite atomistic lattices that can be represented as lattices of quasivarieties
We prove that a finite atomistic lattice can be represented as a lattice of quasivarieties if and only if it is isomorphic to the lattice of all subsemilattices of a finite semilattice. This settles a conjecture that appeared in the context of [11].
Fixed points with respect to the L-slice homomorphism
Given a locale and a join semilattice with bottom element , a new concept called -slice is defined,where is as an action of the locale on the join semilattice . The -slice adopts topological properties of the locale through the action . It is shown that for each , is an interior operator on .The collection is a Priestly space and a subslice of -. If the locale is spatial we establish an isomorphism between the -slices and . We have shown that the fixed set of ,...
Flat semilattices
Free lattices over halflattices
Further results on neutral consensus functions
We use a set theoretic approach to consensus by viewing an object as a set of smaller pieces called “bricks”. A consensus function is neutral if there exists a family D of sets such that a brick s is in the output of a profile if and only if the set of positions with objects that contain s belongs to D. We give sufficient set theoretic conditions for D to be a lattice filter and, in the case of a finite lattice, these conditions turn out to be necessary. Ourfinal result, which involves a finite...
Genomorphisms of lattices and semilattices
GMV-algebras and meet-semilattices with sectionally antitone permutations
Going down in (semi)lattices of finite Moore families and convex geometries
In this paper we first study what changes occur in the posets of irreducible elements when one goes from an arbitrary Moore family (respectively, a convex geometry) to one of its lower covers in the lattice of all Moore families (respectively, in the semilattice of all convex geometries) defined on a finite set. Then we study the set of all convex geometries which have the same poset of join-irreducible elements. We show that this set—ordered by set inclusion—is a ranked join-semilattice and we...
Graph isomorphism of ordered sets
Hilbert algebras as implicative partial semilattices
The infimum of elements a and b of a Hilbert algebra are said to be the compatible meet of a and b, if the elements a and b are compatible in a certain strict sense. The subject of the paper will be Hilbert algebras equipped with the compatible meet operation, which normally is partial. A partial lower semilattice is shown to be a reduct of such an expanded Hilbert algebra i ?both algebras have the same ?lters.An expanded Hilbert algebra is actually an implicative partial semilattice (i.e., a relative...
Hyperarchimedische Teilbarkeitshalbgruppen
Ideals, congruences and annihilators on nearlattices
By a nearlattice is meant a join-semilattice having the property that every principal filter is a lattice with respect to the semilattice order. We introduce the concept of (relative) annihilator of a nearlattice and characterize some properties like distributivity, modularity or -distributivity of nearlattices by means of certain properties of annihilators.
Ideals in distributive posets
We prove that any ideal in a distributive (relative to a certain completion) poset is an intersection of prime ideals. Besides that, we give a characterization of n-normal meet semilattices with zero, thus generalizing a known result for lattices with zero.
Incomparably continuable sets of semilattices
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.