Context: Inheritance is the cornerstone of object-oriented development, supporting conceptual modeling, subtype polymorphism and software reuse. But inheritance can be used in subtle ways that make complex systems hard to understand and extend, due to the presence of implicit dependencies in the inher-

This paper describes a tool for acquiring unknown words, which operates in a bilingual human-machine dialogue system. When the user’s utterance includes a word which is not in the system’s lexicon, the system initiates a subdialogue to find out about the new word, by querying the user about the syntactic validity of a number of example sentences generated automatically from the grammar’s test s...

Refactoring is a method for improving the structure of programs/specifications as to enhance readability, modularity and reusability. Refactorings are required to be behaviour-preserving in that – to an external observer – no difference between the program before and after refactoring is visible. In this paper, we develop refactorings for an object-oriented specification formalism combining a s...

Selection criteria in OODB refer to object properties as well as to type membership. The latter stimulated research on type hierarchy indexing, i.e, fast access to object sets based on type membership criteria. A recent proposal in this context is the multikey type index. It is based on a symmetrical multikey search structure with n dimensions for n indexed object properties and one additional ...

We survey nearly 1300 OWL ontologies and RDFS schemas. The collection of statistical data allows us to perform analysis and report some trends. Though most of the documents are syntactically OWL Full, very few stay in OWL Full when they are syntactically patched by adding type triples. We also report the frequency of occurrences of OWL language constructs and the shape of class hierarchies in t...

Object-oriented case representations require approaches for similarity assessment that allow to compare two differently structured objects, in particular, objects belonging to different object classes. Currently, such similarity measures are developed more or less in an ad-hoc fashion. It is mostly unclear, how the structure of an object-oriented case model, e.g., the class hierarchy, influence...

In this paper I address the phenomenon of syncretism in German and show how Flickinger (2000)’s approach to related issues in English can be adapted to provide a compact, disjunction-free representation of German nominal paradigms by means of combined case/number/gender type hierarchies. In particular, I will discuss the issue of case identity constraints in German coordinate structures, which ...

The monadic second-order quantiier alternation hierarchy over the class of nite graphs is shown to be strict. The proof is based on automata theoretic ideas and starts from a restricted class of graph-like structures, namely nite two-dimensional grids. Considering grids where the width is a function of the height, we prove that the diierence between the levels k +1 and k of the monadic hierarch...

We show that the Borel hierarchy of the class of context free ω-languages, or even of the class of ω-languages accepted by Büchi 1-counter automata, is the same as the Borel hierarchy of the class of ω-languages accepted by Turing machines with a Büchi acceptance condition. In particular, for each recursive non null ordinal α, there exist some Σ α -complete and some Π α -complete ω-languages ac...

This paper is concerned with an effective hierarchy of guaranteed processes. A process satisfies a guarantee requirement when that requirement holds at some forthcoming point of every computation. Cy being the class of w-languages accepted by the base of this process hierarchy, this class of processes, namely Or, is a class of universal machines. Translated in these terms, our results throw lig...