Kaiserslautern - Fachbereich Informatik
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Typical instances, that is, instances that are representative for a particular situ-ation or concept, play an important role in human knowledge representationand reasoning, in particular in analogical reasoning. This wellADknown obser-vation has been a motivation for investigations in cognitive psychology whichprovide a basis for our characterization of typical instances within conceptstructures and for a new inference rule for justified analogical reasoning withtypical instances. In a nutshell this paper suggests to augment the proposi-tional knowledge representation system by a non-propositional part consistingof concept structures which may have directly represented instances as ele-ments. The traditional reasoning system is extended by a rule for justifiedanalogical inference with typical instances using information extracted fromboth knowledge representation subsystems.
Unification in an Extensional Lambda Calculus with Ordered Function Sorts and Constant Overloading
(1999)
We develop an order-sorted higher-order calculus suitable forautomatic theorem proving applications by extending the extensional simplytyped lambda calculus with a higher-order ordered sort concept and constantoverloading. Huet's well-known techniques for unifying simply typed lambdaterms are generalized to arrive at a complete transformation-based unificationalgorithm for this sorted calculus. Consideration of an order-sorted logicwith functional base sorts and arbitrary term declarations was originallyproposed by the second author in a 1991 paper; we give here a correctedcalculus which supports constant rather than arbitrary term declarations, aswell as a corrected unification algorithm, and prove in this setting resultscorresponding to those claimed there.
Most automated theorem provers suffer from the problemthat the resulting proofs are difficult to understand even for experiencedmathematicians. An effective communication between the system andits users, however, is crucial for many applications, such as in a mathematical assistant system. Therefore, efforts have been made to transformmachine generated proofs (e.g. resolution proofs) into natural deduction(ND) proofs. The state-of-the-art procedure of proof transformation fol-lows basically its completeness proof: the premises and the conclusionare decomposed into unit literals, then the theorem is derived by mul-tiple levels of proofs by contradiction. Indeterminism is introduced byheuristics that aim at the production of more elegant results. This inde-terministic character entails not only a complex search, but also leads tounpredictable results.In this paper we first study resolution proofs in terms of meaningful op-erations employed by human mathematicians, and thereby establish acorrespondence between resolution proofs and ND proofs at a more ab-stract level. Concretely, we show that if its unit initial clauses are CNFsof literal premises of a problem, a unit resolution corresponds directly toa well-structured ND proof segment that mathematicians intuitively un-derstand as the application of a definition or a theorem. The consequenceis twofold: First it enhances our intuitive understanding of resolutionproofs in terms of the vocabulary with which mathematicians talk aboutproofs. Second, the transformation process is now largely deterministicand therefore efficient. This determinism also guarantees the quality ofresulting proofs.
Using an experience factory is one possible concept for supporting and improving reuse in software development. (i.e., reuse of products, processes, quality models, ...). In the context of the Sonderforschungsbereich 501: "Development of Large Systems with Generic methods" (SFB501), the Software Engineering Laboratory (SE Lab) runs such an experience factory as part of the infrastructure services it offers. The SE Lab also provides several tools to support the planning, developing, measuring, and analyzing activities of software development processes. Among these tools, the SE Lab runs and maintains an experience base, the SFB-EB. When an experience factory is utilized, support for experience base maintenance is an important issue. Furthermore, it might be interesting to evaluate experience base usage with regard to the number of accesses to certain experience elements stored in the database. The same holds for the usage of the tools provided by the SE LAB. This report presents a set of supporting tools that were designed to aid in these tasks. These supporting tools check the experience base's consistency and gather information on the usage of SFB-EB and the tools installed in the SE Lab. The results are processed periodically and displayed as HTML result reports (consistency checking) or bar charts (usage profiles).
Comprehensive reuse and systematic evolution of reuse artifacts as proposed by the Quality Improvement Paradigm (QIP) do not only require tool support for mere storage and retrieval. Rather, an integrated management of (potentially reusable) experience data as well as project-related data is needed. This paper presents an approach exploiting object-relational database technology to implement the QIP-driven reuse repository of the SFB 501. Requirements, concepts, and implementational aspects are discussed and illustrated through a running example, namely the reuse and continuous improvement of SDL patterns for developing distributed systems. Based on this discussion, we argue that object-relational database management systems (ORDBMS) are best suited to implement such a comprehensive reuse repository. It is demonstrated how this technology can be used to support all phases of a reuse process and the accompanying improvement cycle. Although the discussions of this paper are strongly related to the requirements of the SFB 501 experience base, the basic realization concepts, and, thereby, the applicability of ORDBMS, can easily be extended to similar applications, i. e., reuse repositories in general.
Versions- und Konfigurationsmanagement sind zentrale Instrumente zur intellektuellen Beherrschung komplexer Softwareentwicklungen. In stark wiederverwendungsorientierten Softwareentwicklungsansätzen -wie vom SFB bereitgestellt- muß der Begriff der Konfiguration von traditionell produktorientierten Artefakten auf Prozesse und sonstige Entwicklungserfahrungen erweitert werden. In dieser Veröffentlichung wird ein derartig erweitertes Konfigurationsmodell vorgestellt. Darüberhinau wird eine Ergänzung traditioneller Projektplanungsinformationen diskutiert, die die Ableitung maßgeschneiderter Versions- und Konfigurationsmanagementmechanismen vor Projektbeginn ermöglichen.
Struktur und Werkzeuge des experiment-spezifischen Datenbereichs der SFB501 Erfahrungsdatenbank
(1999)
Software-Entwicklungsartefakte müssen zielgerichtet während der Durchführung eines Software- Projekts erfasst werden, um für die Wiederverwendung aufbereitet werden zu können. Die methodische Basis hierzu bildet im Sonderforschungsbereich 501 das Konzept der Erfahrungsdatenbank. In ihrem experiment-spezifischen Datenbereich werden für jedes Entwicklungsprojekt alle Software-Entwicklungsartefakte abgelegt, die während des Lebenszyklus eines Projektes anfallen. In ihrem übergreifenden Datenbereich werden all die jenigen Artefakte aus dem experiment-spezifischen Datenbereich zusammengefasst, die für eine Wiederverwendung in nachfolgenden Projekten in Frage kommen. Es hat sich gezeigt, dass bereits zur Nutzung der Datenmengen im experiment- spezifischen Datenbereich der Erfahrungsdatenbank ein systematischer Zugriff notwendig ist. Ein systematischer Zugriff setzt jedoch eine normierte Struktur voraus. Im experiment-spezifischen Bereich werden zwei Arten von Experimenttypen unterschieden: "Kontrollierte Experimente" und "Fallstudien". Dieser Bericht beschreibt die Ablage- und Zugriffsstruktur für den Experimenttyp "Fallstudien". Die Struktur wurde aufgrund der Erfahrungen in ersten Fallstudien entwickelt und evaluiert.