[All BiBTeX entries for this year]

H.A. (Erik) Proper. * Interactive Query Formulation using Spider Queries. *Technical report, Asymetrix Research Laboratory, University of Queensland, Brisbane, Queensland, Australia, 1994.

Effective information disclosure in the context of databases with a large con-ceptual schema is known to be a non-trivial problem. In particular the formula-tion of ad-hoc queries is a major problem in such contexts. Existing approaches for tackling this problem include graphical query interfaces, query by navigation, query by construction, and point to point queries. In this article we propose the spi-der query mechanism as a final corner stone for an easy to use computer supported query formulation mechanism for InfoAssisant.

The basic idea behind a spider query is to build a (partial) query of all information considered to be relevant with respect to a given object type. The result of this process is always a tree that fans out over existing conceptual schema (a spider).

We also provide a brief discussion on the integration of the spider quer mech-anism with the existing query by navigation, query by construction, and point to point query mechanisms.

ITT group. * Documentatie bij Funmath Parser. *Technical report: CSI-N9401, December, Radboud University Nijmegen, 1994.

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S. van Bakel, and M. Fernï¿½ndez. * Strong Normalization of Typeable Rewrite Systems. *Technical report: CSI-R9402, January, Radboud University Nijmegen, 1994.

This paper studies normalization properties of rewrite systems that are typeable using intersection types. It introduces a notion of partial type assignment on Applicative Term Rewrite Systems, that consists of assigning intersection types to function symbols, and specifying the way in which types can be assigned to nodes and edges between nodes in the tree representation of terms.Two operations on types are specified ï¿½ substitution and expansion ï¿½ that are used to define type assignment on terms and rewrite rules, and are proven to be sound on both terms and rewrite rules.Using a more liberal approach to recursion, a general scheme for recursive definitions will be presented, that generalizes primitive recursion. It will be proved that, for all systems that satisfy this scheme, every typeable term is strongly normalizable.

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J.J. Sarbo, and J.I. Farkas. * Concept Sublattices ï¿½ Theory and Applications. *Technical report: CSI-R9404, March, Radboud University Nijmegen, 1994.

We consider the the following problem: Given a ``universe'' of primitive and composed entities, where non-primitive entities may contain other ones (e.g. diagrams in plane geometry).How should we represent these entities, such that their containment relation is decidable?As an answer to this problem we propose a representation based on a Galois connection. Examples illustrating the application of the basic idea in automatic reasoning and modelling human memory are included as well.

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H. Barendregt, H. Wupper, and H. Mulder. * Computable processes. *Technical report: CSI-R9405, May, Radboud University Nijmegen, 1994.

The notions of a (digital synchronous) computable process and the corresponding process control machine are introduced. These concepts are generalizations of the notions of computable function and, say, register machine. Emphasis is put on the difference between the specification, the design, the behaviour, and the realization of computable processes.

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A.H.M. ter Hofstede, and T.F. Verhoef. * Flexible Support of Information Modelling: Is the Game worth the Candle?. *Technical report: CSI-R9406, May, Radboud University Nijmegen, 1994.

The necessity of CASE tools for system development is beyond dispute. The current generation of CASE tools, however, is too inflexible to provide adequate modelling support. One of the porposed solutions to this problem is the devleopment of so-called CASE-shells. A CASE shell is a method independent CASE tool, which may be instantiated with a specific method to become a CASE tool supporting that method. As such, a CASE shell provides complete flexibility. This paper does not address the benefits of CASE shells, as they are completely clear, but focuses on the feasibility of this concept from a theoretical as well as a practical point of view.

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J.L.H. Oei, and E.D. Falkenberg. * Harmonization of Information Systems Modelling and Specification Techniques. *Technical report: CSI-R9407, Technical University Twente, The Netherlands, 1994.

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M.-J. Nederhof. * Efficient generation of random sentences. *Technical report: CSI-R9408, August, Radboud University Nijmegen, 1994.

We discuss the random generation of strings using the grammatical formalism AGFL.This formalism consists of context-free grammars extended with a parameter mechanism, where the parameters range over a finite domain.Our approach consists in static analysis of the combinations of parameter values with which derivations can be constructed. After this analysis, generation of sentences can be performed without backtracking.

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M.-J. Nederhof, and E. Bertsch. * Linear-time suffix recognition for deterministic languages. *Technical report: CSI-R9409, August, Radboud University Nijmegen, 1994.

We show that for any deterministic language it can be decided in linear time whether a string is a suffix of a string in that language. The algorithm which accomplishes this is derived from a pushdown atomaton accepting the language. We also show how this algorithm may be applied for the processing of incorrect input in linear time. We further discuss how parse trees for suffixes and for incorrect input can be constructed.

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A. Max Geerling. * Program transformations and skeletons:formal derivation of parallel programs. *Technical report: CSI-R9411, October, Radboud University Nijmegen, 1994.

This paper describes -- from a software engineering perspective -- a framework for the formal development of parallel algorithms on arbitrary architectures.The algorithms are synthesised in a transformational way, i.e., by applying correctness-preserving rewrite rules to a formal problem specification. The architectures are modelled by skeletons -- higher-order functions that represent elementary computations on a certain architecture. Apart from being an architecture description, skeletons also constitute a goal in the program derivation process. Thus, skeletons form an intermediate language that can be implemented once and for all for a certain architecture.It is shown that the combination of transformational programming and skeletons stimulates the reuse of program derivations. Furthermore, inter-skeleton transformations will provide the means for architecture-independent programdevelopment.Following an introduction on transformational program development and skeletons, the paper elaborates on the details of formal parallel-program development. This is done through a running example in which four problems are transformed into parallel programs for two related architectures, using a single program derivation.

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E. Barendsen, and M. Bezem. * Polymorphic Extensions of Simple Type Structures. *Technical report: CSI-R9412, October, Radboud University Nijmegen, 1994.

The technical contribution of this paper is threefold. First we show how to encode functionals in a `flat' applicative structure by adding oracles to untyped lambda calculus and mimicking the applicative behaviour of the functional with an impredicatively defined reduction relation. The main achievement here is a Church-Rosser result for the extended reduction relation. Second, by combining the previous result with the modelconstruction based on partial equivalence relations, we show how to extend a lambda-closed simple type structure to a model of the polymorphic lambda calculus. Third, we specialize the previous result to a counter model against a simple minimization. This minimization is realized by a bar recursive functional, which contrasts the results of Spector and Girard which imply that the bar recursive functions are exactly those that are definable in the polymorphic lambda calculus. As a spin-off, we obtain directly the non-conservativity of the extensions of Gï¿½del's T with bar recursion, fan functional, and Luckhardt's minimization functional, respectively. For the latter two extensions these results are new.

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