Quantization and the Issue of Time for Various Two-Dimensional Models of Gravity

It is shown that the models of 2D Liouville Gravity, 2D Black Hole- and $R^2$-Gravity are {\em embedded} in the Katanaev-Volovich model of 2D NonEinsteinian Gravity. Different approaches to the formulation of a quantum theory for the above systems are then presented: The Dirac constraints can be solved exactly in the momentum representation, the path integral can be integrated out, and the constraint algebra can be {\em explicitely} canonically abelianized, thus allowing also for a (superficial) reduced phase space quantization. Non--trivial dynamics are obtained by means of time dependent gauges. All of these approaches lead to the {\em same} finite dimensional quantum mechanical system.Comment: 4 pages, LaTeX, Talk given at the Journ\'ees Relativistes '93, TUW930

All Symmetries of Non-Einsteinian Gravity in d=2d =2

The covariant form of the field equations for two--dimensional $R^2$--gravity with torsion as well as its Hamiltonian formulation are shown to suggest the choice of the light--cone gauge. Further a one--to--one correspondence between the Hamiltonian gauge symmetries and the diffeomorphisms and local Lorentz transformations is established, thus proving that there are no hidden local symmetries responsible for the complete integrability of the model. Finally the constraint algebra is shown to have no quantum anomalies so that Dirac's quantization should be applicable.Comment: LaTex, 16 pages, TUW9207, (Some smaller corrections, cross-references updated

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

Selling Beaver Skins in North America and Europe, 1720-1760: The Uses of Fur-Trade Imperialism

Historians have tended to assume that, during the last decades of French rule in Canada, competition in the fur trade and the imperial contest in North America ran along the same lines. The posts of the rival empire on Hudson Bay or south of Lake Ontario are thought to have posed the main threat to the fortunes of the Montreal-based traders established in the heart of Indian lands. This article assesses the evidence for price competition between such distant antagonists in the trade in beaver. Owing to the Compagnie des Indes' pricing policies, this commodity usually fetched a lower price in the French trading system than it did in the one centred on London. There is little sign of a response in the distribution of beaver receipts to changes in the intercolonial price differential. This suggests that Canadian merchants exaggerated the force of foreign competition in order to lend weight to their appeals to the state for an increase in the price of beaver. The paper concludes that the obsession with the external foe, which the official sources have transmitted to historians, has obscured the internal dynamic of the Canadian fur trade during these years.Les historiens supposent généralement que pendant les dernières décennies du Régime français au Canada, la concurrence dans le commerce des fourrures suivait les lignes deforce de la rivalité impériale en Amérique du Nord. Situés sur la baie d'Hudson ou au sud du lac Ontario, les postes de l'empire adverse auraient constitué la principale menace pour les commerçants montréalais établis au coeur du pays indien. Cet article cherche les traces d'une telle concurrence à distance dans le commerce du castor. Il s'agit là d'une fourrure que les politiques de la Compagnie française des Indes rendaient moins chère dans le système commercial français que dans celui centré sur Londres. Or la distribution des recettes du castor entre les concurrents se montre peu sensible aux fluctuations dans cette différence intercoloniale des prix ; il semble bien que les marchands canadiens aient brandi l'épouvantait du concurrent étranger afin d'ajouter du poids à leurs demandes faites à l'Etat d'augmenter le prix du castor. Une conclusion s'impose : cette obsession d'un ennemi externe, transmise aux historiens par les sources officielles, a obscurci la dynamique interne du commerce canadien des fourrures au cours de cette période

Assessment and analysis of students skills and competences

У даній роботі розглянута задача нечіткого логічного висновку для прийняття рішень в задачах підбору контингенту студентів виходячи з вимог потенційних роботодавців, що дозволяє зменшити час на обробку інформації про кандидатів на конкретну посаду.This paper considers the problem of the fuzzy logic inference in order to support the decision making procedure of students’ selection based on the requirements of the potential employers. This approach allows reducing the time spent on the processing of the information about candidates for a certain position. The fuzzy characteristics of the input data set are implemented, the set of fuzzy logic inference rules is defined, the algorithm of fuzzy logic inference, which allows selecting students that better suite for a certain competence, is outlined. For the example we have considered the problem of selection of the best candidate for the position “Junior Front-End Developer” among the set of four sample candidates. By using the set of required skills in the field of front-end web development, we have applied the proposed approach to estimate the scores of such skills for each candidate in order to pick the candidates with the best score

Weak Arithmetical Interpretations for the Logic of Proofs

Artemov established an arithmetical interpretation for the Logics of Proofs LPCS, which yields a classical provability semantics for the modal logic S4. These Logics of Proofs are parameterized by so-called constant specifications CS that state which axioms can be used in the reasoning process, and the arithmetical interpretation relies on the constant specifications being finite. In this paper, we remove this restriction by introducing weak arithmetical interpretations that are sound and complete for a wide class of constant specifications, including infinite ones. In particular, they interpret the full Logic of Proofs LP. Keywords: Logic of Proofs, arithmetical interpretation, BHK semantic

Techniques to Analyze sRNA Protein Cofactor Self-Assembly In Vitro

Post-transcriptional control of gene expression by small regulatory noncoding RNA (sRNA) needs protein accomplices to occur. Past research mainly focused on the RNA chaperone Hfq as cofactor. Nevertheless, recent studies indicated that other proteins might be involved in sRNA-based regulations. As some of these proteins have been shown to self-assemble, we describe in this chapter protocols to analyze the nano-assemblies formed. Precisely, we focus our analysis on Escherichia coli Hfq as a model, but the protocols presented here can be applied to analyze any polymer of proteins. This chapter thus provides a guideline to develop commonly used approaches to detect prokaryotic protein self-assembly, with a special focus on the detection of amyloidogenic polymers

Methodological concepts for integrated assessment of agricultural and environmental policies in SEAMLESS-IF

Agricultural and Food Policy, Environmental Economics and Policy, Farm Management, Land Economics/Use,