Embedding Non-Ground Logic Programs into Autoepistemic Logic for Knowledge Base Combination

In the context of the Semantic Web, several approaches to the combination of ontologies, given in terms of theories of classical first-order logic and rule bases, have been proposed. They either cast rules into classical logic or limit the interaction between rules and ontologies. Autoepistemic logic (AEL) is an attractive formalism which allows to overcome these limitations, by serving as a uniform host language to embed ontologies and nonmonotonic logic programs into it. For the latter, so far only the propositional setting has been considered. In this paper, we present three embeddings of normal and three embeddings of disjunctive non-ground logic programs under the stable model semantics into first-order AEL. While the embeddings all correspond with respect to objective ground atoms, differences arise when considering non-atomic formulas and combinations with first-order theories. We compare the embeddings with respect to stable expansions and autoepistemic consequences, considering the embeddings by themselves, as well as combinations with classical theories. Our results reveal differences and correspondences of the embeddings and provide useful guidance in the choice of a particular embedding for knowledge combination.Comment: 52 pages, submitte

Evaluatieonderzoek (her)ontwikkeling bedrijventerreinen Enschede 2000‐2010

De rekenkamercommissie van de gemeente Enschede heeft het CSTM opdracht gegeven het Enschedese bedrijventerreinenbeleid in de periode 2000‐2010 te evalueren om te bezien in hoeverre door de inzet van instrumenten in deze periode de doelstellingen zijn behaald

Ruby in the dust : poetry and history n Padm¯avat by the Southasian sufipoet Muhammad J¯ayas¯ı

Ruby in the Dust presents an innovative reading of the Indian mystical romance Padmāvat (1540). It describes the semantic polyphony of Jāyasī’s seminal work from the perspective of the poet’s role in the literary field, as mediator between the interests of his spiritual and worldly patrons. The contextual outlook of De Bruijn’s interpretation corrects the identification with modern, nationalist notions of Hindu and Muslim identity that have dominated readings of Padmāvat until now. De Bruijn’s reading reveals the confluence of poetry and history that inspired the many retellings of the tale of Padmāvatī and Ratansen in Persian and other Indian languages9789400600317 (eisbn

Evaluatie Impulsprogramma Zwerfafval 2007-2009

In het najaar van 2009 heeft CSTM in opdracht van de samenwerkende partners\ud (VROM, VNO-NCW, VNG, Stichting Nederland Schoon en SenterNovem) een evaluatieonderzoek uitgevoerd naar de effectiviteit van het Impulsprogramma Zwerfafval 2007-2009. De doelstelling van het evaluatieonderzoek was het geven van inzicht in de behaalde resultaten van het Impulsprogramma zwerfafval, het evalueren van deze resultaten ten opzichte van de gestelde doelen, en het formuleren van aanbevelingen voor een effectieve voortzetting van het impulsprogramma

Distances on Rhombus Tilings

The rhombus tilings of a simply connected domain of the Euclidean plane are known to form a flip-connected space (a flip is the elementary operation on rhombus tilings which rotates 180{\deg} a hexagon made of three rhombi). Motivated by the study of a quasicrystal growth model, we are here interested in better understanding how "tight" rhombus tiling spaces are flip-connected. We introduce a lower bound (Hamming-distance) on the minimal number of flips to link two tilings (flip-distance), and we investigate whether it is sharp. The answer depends on the number n of different edge directions in the tiling: positive for n=3 (dimer tilings) or n=4 (octogonal tilings), but possibly negative for n=5 (decagonal tilings) or greater values of n. A standard proof is provided for the n=3 and n=4 cases, while the complexity of the n=5 case led to a computer-assisted proof (whose main result can however be easily checked by hand).Comment: 18 pages, 9 figures, submitted to Theoretical Computer Science (special issue of DGCI'09

Probability distributions for quantum stress tensors in four dimensions

We treat the probability distributions for quadratic quantum fields, averaged with a Lorentzian test function, in four-dimensional Minkowski vacuum. These distributions share some properties with previous results in two-dimensional spacetime. Specifically, there is a lower bound at a finite negative value, but no upper bound. Thus arbitrarily large positive energy density fluctuations are possible. We are not able to give closed form expressions for the probability distribution, but rather use calculations of a finite number of moments to estimate the lower bounds, the asymptotic forms for large positive argument, and possible fits to the intermediate region. The first 65 moments are used for these purposes. All of our results are subject to the caveat that these distributions are not uniquely determined by the moments. However, we also give bounds on the cumulative distribution function that are valid for any distribution fitting these moments.We apply the asymptotic form of the electromagnetic energy density distribution to estimate the nucleation rates of black holes and of Boltzmann brains.Comment: 26 pages, 2 figure