Showing papers by "Peter Baumgartner published in 2004"

Darwin: A Theorem Prover for the Model Evolution Calculus

Abstract: Darwin is the first implementation of the Model Evolution Calculus by Baumgartner and Tinelli. The Model Evolution Calculus lifts the DPLL procedure to first-order logic. Darwin is meant to be a fast and clean implementation of the calculus, showing its eectiveness and providing a base for further improvements and extensions. Based on a brief summary of the Model Evolution Calculus, we describe in the main part of the paper Darwin’s proof procedure and its data structures and algorithms, discussing the main design decisions and features that influence Darwin’s performance. We also report on practical experiments carried out with problems from the CADE-18 and CADE-19 system competitions, as well as on results on parts of the TPTP Problem Library.

Living Book -- Deduction, Slicing, and Interaction

Abstract: Living Book is a system for the management of personalized and scenario-specific teaching material. The main goal of the system is to support active, explorative, and self-determined learning in lectures, tutorials, and self-study. Living Book includes a course on "logic for computer scientists," with uniform access to various tools such as theorem provers and an interactive tableau editor. It is routinely used in teaching undergraduate courses at our university. This paper describes Living Book, together with its use of theorem-proving technology as a core component in the knowledge management system (KMS) and the use of this new concept in academic teaching. The KMS provides a scenario management component in which teachers may describe those parts of given documents that are relevant in order to achieve a certain learning goal. The task of the KMS is to assemble new documents from a database of elementary units called "slices" (definitions, theorems, and so on) in a scenario-based way (such as, "I want to prepare for an exam and need to learn about resolution"). The computation of such assemblies is carried out by a model-generating theorem prover for first-order logic with a default negation principle. Its input consists of metadata that describes the dependencies between different slices and logic-programming style rules that describe the scenario-specific composition of slices. Additionally, users may assess what units they know or don't know. This information is stored in a user model, which is taken into account to compute a model that specifies the assembly of a personalized document. This paper introduces the e-learning context we are faced with, motivates our choice of logic, and sketches the newly developed calculus used in the KMS. Furthermore, the application and evaluation of Living Book are presented.

Model Based Deduction for Database Schema Reasoning

Abstract: We aim to demonstrate that automated deduction techniques, in particular those following the model computation paradigm, are very well suited for database schema/query reasoning. Specifically, we present an approach to compute completed paths for database or XPath queries. The database schema and a query are transformed to disjunctive logic programs with default negation, using a description logic as an intermediate language. Our underlying deduction system, KRHyper, then detects if a query is satisfiable or not. In case of a satisfiable query, all completed paths – those that fulfill all given constraints – are returned as part of the computed models.

Logic Programming Infrastructure for Inferences on FrameNet

Abstract: The growing size of electronically available text corpora like companies’ intranets or the WWW has made information access a hot topic within Computational Linguistics. Despite the success of statistical or keyword based methods, deeper Knowledge Representation (KR) techniques along with “inference” are often mentioned as mandatory, e.g. within the Semantic Web context, to enable e.g. better query answering based on “semantical” information. In this paper we try to contribute to the open question how to operationalize semantic information on a larger scale. As a basis we take the frame structures of the Berkeley FrameNet II project, which is a structured dictionary to explain the meaning of words from a lexicographic perspective. Our main contribution is a transformation of the FrameNet II frames into the answer set programming paradigm of logic programming.

Optimizing the evaluation of XPath using description logics

Abstract: The growing use of XML in commercial as well as non-commercial domains to transport information poses new challenges to concepts to access this information. Common ways to access parts of a document use XPath-expressions. We provide a transformation of DTDs into a knowledge base in Description Logic. We use reasoning capabilities grounded in description logics to decide if a given XPath can be satisfied by a document, and to guide the search of XML-Processors into possibly successful branches of the document, thus avoiding parts of the document that will not yield results. The extension towards object oriented subclassing schemes opens this approach towards OODB-queries. In contrast to other approaches we do not use any kind of graph representing the document structure, and no steps towards incorporation of the XML/OODB-processor itself will be taken.

Pre-Campanian Terranes in Nicoya area (Costa Rica, Middle America)

Abstract: Detailed field mapping, isotopic and palaeontologic dating in the Nicoya area has revealed coeval preCampanian, middle to late Cretaceous sedimentary/magmatic sequences of different geodynamic palaeoenvironments. 1The Nicoya Complex is a pile of plateau basalts and intrusives of Berriasian to Campanian igneous ages, including Middle Jurassic to Santonian radiolaritic sediments only. This unit is the subject of another abstract (this volume). 2The Matambu Terrane comprises a basaltic basement of unknown origin and age, overlain by bituminous, siliceous shales of late Albian age (Loma Chumico Formation). This formation seems to be thermally affected by younger basaltic flows and intrusives of Cenomanian to early Campanian age that may be part of the Nicoya (plateau) Complex. The Loma Chumico Formation is overlain by pelagic, hemipelagic and turbiditic siliceous and calcareous shales and mudstones assigned to the redefined Sabana Grande Formation (palaeontologically undated, but estimated as Cenomanian to Coniancian in age). Upsection, the Nambi Formation (Flores et al. 2003) is characterized by volcaniclastic turbidities that document erosion of the (nearby) Nicoya Complex. A preliminary Sr/Sr isotopic analysis of Inoceramus gave a value of 0.70738 that can be interpreted as a Coniacian age. The top of Nambi is marked by the presence of reworked Campanian shallow water bioclasts, announcing the transition to the overlap sediments (see below). 3The Manzanillo Terrane is floored by a basaltic basement intruded by the Tortugual Komatiitic Suite (Alvarado et al. 1997) of Turonian (89 ma) age. The sedimentary cover is characterized by a thick hemipelagic-turbiditic sequence containing arc-derived volcaniclastic deposits called Berrugate Formation (Flores et al. 2003). This formation has been dated by radiolarian biochronology as Coniancian in age (Dictyomitra koslovae, Pseudoaulophacus florensis, Pseudoaulophacus lenticulatus and Theocampe salillum associated with Stichomitra communis), but may range up to the lower Campanian. The Manzanillo Terrane documents pre-Campanian evolved arc volcanism that must have resulted from active subduction of “normal” ocean floor. This ocean floor was located between the exotic Nicoya Complex (1) /Matambu Terrane (2), and the Manzanillo Terrane (3). The Manzanillo Terrane could represent a fore-arc area at the foot of the western edge of the future Caribbean Plate. Subduction stopped when (1) and (2) reached the trench and collided with the Caribbean Plate during the Campanian. Di Marco et al. (1995) provided evidence for Late Campanian-Maastrichtian southern hemisphere palaeolatitudes in two sections of the Figure 1 Terranes proposed in Nicoya area

In2Math - Interaktive Mathematik- und Informatikgrundausbildung

Abstract: Das In2Math Projekt wurde vom BMBF gefördert und hatte eine Laufzeit von drei Jahren (2001 bis 2003). Die beteiligten Partner sind die Universität Koblenz-Landau (Prof. Dr. Ulrich Furbach, Koordinator), Humboldt-Universität zu Berlin (Dr. Marco Roczen), die Universität Paderborn (Prof. Dr. Benno Fuchssteiner), die Hochschule für Technik und Wirtschaft des Saarlandes (Prof. Dr. Barbara Grabowski), sowie die Universität des Saarlandes (Prof. Dr. Jörg Siekmann, PD Dr. Erika Melis). Des weiteren waren die Unterauftragnehmer DFKI Saarbrücken, die SciFace GmbH, die SIT GmbH, der Springer-Verlag und die Firma ergosign beteiligt.