arXiv subjects
Publications and source records attributed to Dominic van der Zypen.
Let $(P,\leq)$ be a partially ordered set and let $τ$ be a compact topology on $P$ that is finer than the interval topology. Then $τ$ is contained in the order (convergence) topology on $(P,τ)$. So any Priestley topology is contained in the order topology.
A partially ordered set P is representable if there is a bounded distributive lattice such that its ordered set of prime ideals is order-isomorphic to P. We show that if the order components of a poset P are representable, then so is P. Moreover, we provide an example disproving the converse.
We characterise the Priestley spaces corresponding to affine complete bounded distributive lattices. Moreover we prove that the class of affine complete bounded distributive lattices is closed under products and free products. We show that every (not necessarily bounded) distributive lattice can be embedded in an affine complete one and that $\mathbb{Q} \cap [0,1]$ is initial in the class of affine complete lattices.
Let X be a topological space. The closure of Δ= {(x, x) : x \in X} in X \times X is a symmetric relation on X. We characterise those equivalence relations on an infinite set that arise as the closure of the diagonal with respect to a T_1-topology.
The ordering relation of a bounded distributive lattice L is a (distributive) (0, 1)-sublattice of L \times L. This construction gives rise to a functor Φfrom the category of bounded distributive lattices to itself. We examine the interaction of Φwith Priestley duality and characterise those bounded distributive lattices L such that there is a bounded distributive lattice K such that Φ(K) is (isomorphic to) L.
We revisit the known problem whether each compact topology is contained in a maximal compact topology and collect some partial answers to this question. For instance we show that each compact topology is contained in a compact topology in which convergent sequences have unique limits. We also answer a question of D.E. Cameron by showing that each sequentially compact topology is contained in a maximal sequentially compact topology. We finally observe that each sober compact T_1-topology is contained in a maximal compact topology and that each sober compact T_1-topology which is locally compact or sequential is the infimum of a family of maximal compact topologies.