Proper congruences do not imply a modular congruence lattice
Proper hypersubstitutions of some generalizations of lattices and Boolean algebras
Properties of complements in the lattice of convergence structures.
Properties of monotone mappings in partially ordered sets.
Properties of Prealgebraic Lattices Investigated by Means of Formal Concept Analysis
Properties of relatively pseudocomplemented directoids
The concept of a relatively pseudocomplemented directoid was introduced recently by the first author. It was shown that the class of relatively pseudocomplemented directoids forms a variety whose axiom system contains seven identities. The aim of this paper is three-fold. First we show that these identities are not independent and their independent subset is presented. Second, we modify the adjointness property known for relatively pseudocomplemented semilattices in the way which is suitable for...
Propiedades topológicas de los grupos de isometría de un grupo reticulado.
This paper deals with the topological properties of groups of isometries of lattice-ordered groups and f-rings. The topologies considered are order-topology and the topology defined by null-sequences.
Propos sur la théorie du mesurage
Prüfer -groups
P-sets and minimal right ideals in ℕ*
Recall that a P-set is a closed set X such that the intersection of countably many neighborhoods of X is again a neighborhood of X. We show that if 𝔱 = 𝔠 then there is a minimal right ideal of (βℕ,+) that is also a P-set. We also show that the existence of such P-sets implies the existence of P-points; in particular, it is consistent with ZFC that no minimal right ideal is a P-set. As an application of these results, we prove that it is both consistent with and independent of ZFC that the shift...
Pseudo -algebras and -monoids
It is shown that pseudo -algebras are categorically equivalent to certain bounded -monoids. Using this result, we obtain some properties of pseudo -algebras, in particular, we can characterize congruence kernels by means of normal filters. Further, we deal with representable pseudo -algebras and, in conclusion, we prove that they form a variety.
Pseudo-closure-operators
Pseudocompactness and the cozero part of a frame
A characterization of the cozero elements of a frame, without reference to the reals, is given and is used to obtain a characterization of pseudocompactness also independent of the reals. Applications are made to the congruence frame of a -frame and to Alexandroff spaces.
Pseudocomplemented and Stone Posets
We show that every pseudocomplemented poset can be equivalently expressed as a certain algebra where the operation of pseudocomplementation can be characterized by means of remaining two operations which are binary and nullary. Similar characterization is presented for Stone posets.
Pseudocomplemented directoids
Directoids as a generalization of semilattices were introduced by J. Ježek and R. Quackenbush in 1990. We modify the concept of a pseudocomplement for commutative directoids and study several basic properties: the Glivenko equivalence, the set of the so-called boolean elements and an axiomatization of these algebras.
Pseudo-complemented distributive groupoids
Pseudocomplemented ordered sets
The aim of this paper is to transfer the concept of pseudocomplement from lattices to ordered sets and to prove some basic results holding for pseudocomplemented ordered sets.
Pseudocomplements in sum-ordered partial semirings
We study a particular way of introducing pseudocomplementation in ordered semigroups with zero, and characterise the class of those pseudocomplemented semigroups, termed g-semigroups here, that admit a Glivenko type theorem (the pseudocomplements form a Boolean algebra). Some further results are obtained for g-semirings - those sum-ordered partially additive semirings whose multiplicative part is a g-semigroup. In particular, we introduce the notion of a partial Stone semiring and show that several...
Pseudodimension of relational structures
Pseudo-galois Extensions of Boolean Algebras