11 research outputs found
Bitopological Duality for Distributive Lattices and Heyting Algebras
We introduce pairwise Stone spaces as a natural bitopological generalization of Stone spaces—the duals of Boolean algebras—and show that they are exactly the bitopological duals of bounded distributive lattices. The category PStone of pairwise Stone spaces is isomorphic to the category Spec of spectral spaces and to the category Pries of Priestley spaces. In fact, the isomorphism of Spec and Pries is most naturally seen through PStone by first establishing that Pries is isomorphic to PStone, and then showing that PStone is isomorphic to Spec. We provide the bitopological and spectral descriptions of many algebraic concepts important for the study of distributive lattices. We also give new bitopological and spectral dualities for Heyting algebras, co-Heyting algebras, and bi-Heyting algebras, thus providing two new alternatives of Esakia’s duality
A non-commutative Priestley duality
We prove that the category of left-handed strongly distributive skew lattices
with zero and proper homomorphisms is dually equivalent to a category of
sheaves over local Priestley spaces. Our result thus provides a non-commutative
version of classical Priestley duality for distributive lattices and
generalizes the recent development of Stone duality for skew Boolean algebras.
From the point of view of skew lattices, Leech showed early on that any
strongly distributive skew lattice can be embedded in the skew lattice of
partial functions on some set with the operations being given by restriction
and so-called override. Our duality shows that there is a canonical choice for
this embedding.
Conversely, from the point of view of sheaves over Boolean spaces, our
results show that skew lattices correspond to Priestley orders on these spaces
and that skew lattice structures are naturally appropriate in any setting
involving sheaves over Priestley spaces.Comment: 20 page
Ordered Locales
We extend the Stone duality between topological spaces and locales to include order: there is an adjunction between the category of preordered topological spaces satisfying the so-called open cone condition, and the newly defined category of ordered locales. The adjunction restricts to an equivalence of categories between spatial ordered locales and sober T 0-ordered spaces with open cones.</p
Ultraposet, Distributive Lattice, and Coherent Locale
In this paper, we provide an alternative description of the duality result
for distributive lattices and coherent locales using ultraposet. In particular,
we show that there are fully faithful embeddings from the opposite of the
category of distributive lattices into the category of ultraposets with
ultrafunctors, and from the category of coherent locales into the category of
ultraposets with left ultrafunctors. We also define the notion of
zero-dimensional ultraposets, which characterises the essential image of these
embeddings.Comment: 36 pages excluding appendi
Representations and Completions for Ordered Algebraic Structures
The primary concerns of this thesis are completions and representations for various classes of
poset expansion, and a recurring theme will be that of axiomatizability. By a representation we
mean something similar to the Stone representation whereby a Boolean algebra can be homomorphically
embedded into a field of sets. So, in general we are interested in order embedding
posets into fields of sets in such a way that existing meets and joins are interpreted naturally as
set theoretic intersections and unions respectively.
Our contributions in this area are an investigation into the ostensibly second order property
of whether a poset can be order embedded into a field of sets in such a way that arbitrary meets
and/or joins are interpreted as set theoretic intersections and/or unions respectively. Among
other things we show that unlike Boolean algebras, which have such a ‘complete’ representation
if and only if they are atomic, the classes of bounded, distributive lattices and posets with
complete representations have no first order axiomatizations (though they are pseudoelementary).
We also show that the class of posets with representations preserving arbitrary joins is
pseudoelementary but not elementary (a dual result also holds).
We discuss various completions relating to the canonical extension, whose classical construction
is related to the Stone representation. We claim some new results on the structure of
classes of poset meet-completions which preserve particular sets of meets, in particular that they
form a weakly upper semimodular lattice. We make explicit the construction of \Delta_{1}-completions
using a two stage process involving meet- and join-completions.
Linking our twin topics we discuss canonicity for the representation classes we deal with,
and by building representations using a meet-completion construction as a base we show that
the class of representable ordered domain algebras is finitely axiomatizable. Our method has
the advantage of representing finite algebras over finite bases