Modal definability in topology Master's thesis Acknowledgments During the year spent in Amsterdam at ILLC I have been lucky to be supported by many. The proper acknowledgment of everyone would have resulted in a separate book. I will only name a few, with the hope that the others will find my gratitude in between the lines. I am greatly indebted to Dr. Yde… (More)
Acknowledgments I am truly grateful to my two advisers, Jeroen Groenendijk and Dick de Jongh, without whom (needless to say, though I'll say it anyway) this thesis wouldn't have existed. I was fortunate enough to meet Jeroen early on in my days at the ILLC and to have established such a fruitful collaboration; Jeroen is an inspiring teacher and an inspired… (More)
In this paper the system IL for relative interpretability described in Visser (1988) is studied. 1 In IL formulae A| > B (read: A interprets B) are added to the provability logic L. The intended interpretation of a formula A| > B in an (arithmetical) theory T is: T + B is relatively interpretable in T + A. The system has been shown to be sound with respect… (More)
This article ~s a report on research m progress into the structure of fimte diagrams of mtuinomst~c proposmonal logic with the aid of automated reasoning systems for larger calculanons. A/ragment of a proposmonal logic is the set of formulae built up from a fimte number of proposinonal variables by means of a number of connectives of the logic, among which… (More)
The non-classical, nonmonotonic inference relation associated with the answer set semantics for logic programs gives rise to a relationship of strong equivalence between logical programs that can be verified in 3-valued Gödel logic, G3, the strongest non-classical intermediate propositional logic (Lifschitz, Pearce and Valverde, 2001). In this paper we will… (More)
We extend Angluin's (1980) theorem to characterize identiiability of indexed families of r.e. languages, as opposed to indexed families of recursive languages. We also prove some variants characterizing conservativity a n d t wo other similar restrictions, paralleling Zeug-mann, Lange, and Kapur's (1992, 1995) results for indexed families of recursive… (More)
We investigate fragments of intuitionistic propositional logic containing implication but not disjunction. These fragments are finite, but their size grows superexponentially with the number of generators. Exact models are used to characterize the fragments.