In this paper a simple proof of the completeness theorem of the intuitionistic predicate calculus with respect to the topological semantics is shown. From a technical point of view the proof of the completeness theorem is based on a Rasiowa-Sikirski-like theorem for the countable Heyting algebras which allows to embadd any countable Heyting algebra into a suitable topology in a such way that a ...

In this series of lectures, we will a) introduce the basics of ominimality, b) describe the manifold topology of groups definable in o-minimal structures, and c) present a structure theorem for the special case of semi-linear groups, exemplifying their relation with real Lie groups. The structure of these lectures is as follows: (1) Basics of o-minimality: definition, Cell Decomposition Theorem...

A: Well, yes, Yuri asked me if I wanted to write a logic column, and suggested to talk to you for some inspiration. Q: Sure, we can talk. Do you already have an idea what you will write about? A: I was thinking, perhaps I could write about first-order topological properties. Q: I suppose that is first-order as in " first-order logic " , but what's about the topol-ogy? I'm afraid I do not know m...

An l-group G is an abelian group equipped with a translation invariant lattice order. Baker and Beynon proved that G is finitely generated projective iff it is finitely presented. A unital l-group is an l-group G with a distinguished order unit, i.e., an element 0 ≤ u ∈ G whose positive integer multiples eventually dominate every element of G. While every finitely generated projective unital l-...

The paper is devoted to the study of topologies on the group Aut(X, B) of all Borel automorphisms of a standard Borel space (X, B). Several topologies are introduced and all possible relations between them are found. One of these topologies, τ , is a direct analogue of the uniform topology widely used in ergodic theory. We consider the most natural subsets of Aut(X, B) and find their closures. ...

For even dimensional manifolds, we prove some twisted anomaly cancellation formulas which generalize some well-known cancellation formulas. For odd dimensional manifolds, we obtain some modularly invariant characteristic forms by the Chern-Simons transgression and we also get some twisted anomaly cancellation formulas. Subj. Class.: Differential geometry; Algebraic topology MSC: 58C20; 57R20; 5...

Countable compactifications of topological spaces have been studied in [1], [5], [7], and [9]. In [7], Magill showed that a locally compact, T2 topological space X has a countable T2 compactification if and only if it has n-point T2 compactifications for every integer n ≥ 1. We generalize this theorem to T2-ordered compactifications of ordered topological spaces. Before starting our generalizat...

0. Introduction. If (X,≤) is a partially ordered set and A ⊆ X, then the decreasing hull d(A) of A in X is defined to be d(A) = {x ∈ X : x ≤ a for some a ∈ A}. If the poset X is not understood from the context, we may write dX(A). A subset A ⊆ X is a decreasing set if A = d(A). The intersection or union of any collection of decreasing sets in X is again a decreasing set in X. The increasing hul...

In this paper we study important quantities defined from solutions of first order linear systems of ordinary differential equations. It will be proved that many quantities, such as solutions, eigenvalues of one-dimensional Dirac operators, Lyapunov exponents and rotation numbers, depend on the coefficients in a very strong way. That is, they are not only continuous in coefficients with respect ...

One of the many gifts from Alan to Set-theoretic Topology is the use of elementarity. For a while this was even known as “Dow’s method of elementary submodels”. But Alan would be, was, and still is the first to protest that the Löwenheim-Skolem theorem predates him by a few decades. We have for the longest time been familiar with recursive constructions where often beforehand a sequence of situ...