Reasoning about temporal relations : a maximal tractable subclass of Allen\u27s interval algebra

We introduce a new subclass of Allen\u27s interval algebra we call "ORD-Horn subclass", which is a strict superset of the "pointisable subclass". We prove that reasoning in the ORD-Horn subclass is a polynomial-time problem and show that the path-consistency method is sufficient for deciding satisfiability. Further, using an extensive machine-generated case analysis, we show that the ORD-Horn subclass is a maximal tractable subclass of the full algebra (assuming P neq NP). In fact, it is the unique greatest tractable subclass amongst the subclasses that contain all basic relations

An empirical analysis of terminological representation systems

The family of terminological representation systems has its roots in the representation system KL-ONE. Since the development of this system more than a dozen similar representation systems have been developed by various research groups. These systems vary along a number of dimensions.In this paper, we present the results of an empirical analysis of six such systems. Surprisingly, the systems turned out to be quite diverse leading to problems when transporting knowledge bases from one system to another. Additionally, the runtime performance between different systems and knowledge bases varied more than we expected. Finally, our empirical runtime performance results give an idea of what runtime performance to expect from such representation systems. These findings complement previously reported analytical results about the computational complexity of reasoning in such systems

Reasoning about temporal relations : a maximal tractable subclass of Allen's interval algebra

We introduce a new subclass of Allen's interval algebra we call "ORD-Horn subclass", which is a strict superset of the "pointisable subclass". We prove that reasoning in the ORD-Horn subclass is a polynomial-time problem and show that the path-consistency method is sufficient for deciding satisfiability. Further, using an extensive machine-generated case analysis, we show that the ORD-Horn subclass is a maximal tractable subclass of the full algebra (assuming P neq NP). In fact, it is the unique greatest tractable subclass amongst the subclasses that contain all basic relations

An empirical analysis of optimization techniques for terminological representation systems : or: \u27Making KRIS get a move on\u27

We consider different methods of optimizing the classification process of terminological representation systems, and evaluate their effect on three different types of test data. Though these techniques can probably be found in many existing systems, until now there has been no coherent description of these techniques and their impact on the performance of a system. One goal of this paper is to make such a description available for future implementors of terminological systems. Building the optimizations that came off best into the KRIS system greatly enhanced its efficiency

Terminological knowledge representation : a proposal for a terminological logic

This paper contains a proposal for a terminological logic. The formalisms for representing knowledge as well as the needed inferences are described

On the expressivity of feature logics with negation, functional uncertainty, and sort equations

Feature logics are the logical basis for so-called unification grammars studied in computational linguistics. We investigate the expressivity of feature terms with complements and the functional uncertainty construct needed for the description of long-distance dependencies and obtain the following results: satisfiability of feature terms is undecidable, sort equations can be internalized, consistency of sort equations is decidable if there is at least one atom, and consistency of sort equations is undecidable if there is no atom

“Geographiedidaktische Forschungen” (GDF) from 1977 to 2017–A Possible Mirror of the Development and the Discourses on Geography Didactics in Germany Over the Past 40 Years?

Der vorliegende Beitrag wirft anlässlich des vierzigjährigen Bestehens der Schriftenreihe „Geo graphiedidaktische Forschungen“ des Hochschulverbandes für Geographiedidaktik (HGD) einen Blick zurück auf die Entwicklung der Reihe und beleuchtet zugleich mit Blick nach vorne zukünf tige Handlungsfelder. Dabei liegt der Fokus neben Informationen zur Zielstellung, zu den Grün dungskontexten sowie zu formalen und personellen Veränderungen der Schriftenreihe auf einer Dokumentation der 67 bislang erschienenen Bände, ihrer thematischen Schwerpunkte und Bei tragsformate. Im Rahmen des Beitrags soll zudem der Frage nachgegangen werden, inwiefern die Schriftenreihen einen Spiegel geographiedidaktischer Entwicklungen und Diskurse in Deutschland repräsentiert.In the occasion of the 40th anniversary of the publication series "Geographiedidaktische For schungen" by Hochschulverband für Geographiedidaktik (HGD) this article gives a look back at the development of the series and, at the same time, highlights on future areas of action. In addition to information on the objectives, founding contexts and formal and personal changes in the series, the focus is on the documentation of the 67 volumes published so far, their thematic focuses and contribution format

On the expressivity of feature logics with negation, functional uncertainty, and sort equations

Feature logics are the logical basis for so-called unification grammars studied in computational linguistics. We investigate the expressivity of feature terms with complements and the functional uncertainty construct needed for the description of long-distance dependencies and obtain the following results: satisfiability of feature terms is undecidable, sort equations can be internalized, consistency of sort equations is decidable if there is at least one atom, and consistency of sort equations is undecidable if there is no atom

Reasoning about Temporal Relations: A Maximal Tractable Subclass of Allen's Interval Algebra

We introduce a new subclass of Allen's interval algebra we call "ORDHorn subclass," which is a strict superset of the "pointisable subclass." We prove that reasoning in the ORD-Horn subclass is a polynomial-time problem and show that the path-consistency method is sufficient for deciding satisfiability. Further, using an extensive machine-generated case analysis, we show that the ORD-Horn subclass is a maximal tractable subclass of the full algebra (assuming<F NaN> P6=NP). In fact, it is the unique greatest tractable subclass amongst the subclasses that contain all basic relations. This work has been supported by the German Ministry for Research and Technology (BMFT) under grant ITW 8901 8 as part of the WIP project and under grant ITW 9201 as part of the TACOS project. 1 1 Introduction Temporal information is often conveyed qualitatively by specifying the relative positions of time intervals such as ". . . point to the figure while explaining the performance of the system . . . "..