[All BiBTeX entries for this year]

H.A. (Erik) Proper. * Da Vinci - Architecture-Driven Business Solutions. *Technical report, Summer, Origin, Utrecht, The Netherlands, EU, 1998.

This document has emerged out of Origin's past experiences with architecture-driven application development (AD2), and the need to further formalise and consolidate these experiences.

The AD2 related developments range in scope from the actual design and implementation of applications, to the development of a long-term vision of an organisation's business activities and IT support required. The main concern of AD2 is the development of applications to support an organisation's business activities, by considering the entire context of the applications.

J.E. Schuur, P. van Bommel, and F.G. Zitman. * A Clinical Information System for Psychiatry. *Technical report: CSI-R9801, January, Radboud University Nijmegen, 1998.

At the Academic Hospital of Nijmegen (AZN) a project is started with the aim to improvethe quality of patient care and to facilitate patient directed scientific research, by introducingstandardized procedures and assessment tools that will be offered by a computerized information system. Theresulting Clinical Information System (CIS) should reflect the contributions of all associated disciplinesat the department: psychiatrists, psychologists, nurses, social workers, and occupational therapists.One of the main problems that arised during the beginning of the project is thesimultaneous restoration and development of a new general Hospital Information System (HIS) at the AZN, theRadboud Order Communication System (ROCS). Many procedures that were supposed to be components of theCIS, appeared to be components of the new HIS. The CIS should be based on the HIS in order toprovide an optimal redundancy in data and integration of both systems. We studied the proposedcomponents of the CIS and compared these with the components of the HIS in order to redefine the contentsof this project.We found that ROCS provides almost all components of the current clinical practice at the department of psychiatry. However, the introduction of some standardized procedures and assessment tools are not or not fully provided by the HIS. Consequently, these extensions to the current information system are the candidate components of this project: the pharmacological treatment procedure, and the assessment tools.

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G. Debrock, and J.J. Sarbo. * Towards a Peircean modelof language. *Technical report: CSI-R9802, February, Radboud University Nijmegen, 1998.

We argue that traditional approaches to natural language suffer from the �fallacy of misplaced concreteness�. Because �language� is a noun, and nouns usually refer to �things�, it often assumed that language is some �thing� with a certain immutable structure and properties. This problem of language modelling is also witnessed by the limited success of phrase structure-based parsers in natural language processing. One reason for this lies in the rigidity of hierarchical structure on the one hand, as opposed to the high flexibility of language use on the other.It will be argued that language is in the first place a process, and that this assumption puts the task of an analysis of language in a different perspective. A model supporting this view is Natural Language Concept Analysis (NLCA). In NLCA, hierarchical structure is found as the result of the interaction of different, inherent combinatorial properties of linguistic units. The purpose of the paper is to show that NLCA is consistent with C.S. Peirce�s pragmatic, evolutionary and semeiotic approach, and that such approach supports and clarifies NLCA.

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D.C. van Leijenhorst. * Symmetric functions, I:. *Technical report: CSI-R9803, January, Radboud University Nijmegen, 1998.

The symmetric complexity of a polynomial f in n var iables is defined as the number of times the symmetric function theorem is applicable. In this paper a sharp upper bound on this measure is derived by a matrix method.

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D.C. van Leijenhorst. * Parallel Sorting - the Zamfir Way. *Technical report: CSI-R9804, January, Radboud University Nijmegen, 1998.

A simple heuristic is given for Batcher�s famous algorithm, which makes this parallel sorting method easy to understand for (practically) anybody, panflautists included.

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Rhinefish Facth. * Symmetric functions, II:. *Technical report: CSI-R9805, January, Radboud University Nijmegen, 1998.

An elementary combinatorial version of the symmetric function theorem leads to an interesting Diophantine equation. It is proved that the only finite field admitting such a theorem is GF(2).

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D.C. van Leijenhorst. * GA�s in Optical Design - Addendum:. *Technical report: CSI-R9806, January, Radboud University Nijmegen, 1998.

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M.I.A. Stoelinga. * Processes and their Identifiers in Synchronous Network Systems. *Technical report: CSI-R9807, March, Radboud University Nijmegen, 1998.

This report formalizes the two notions of �comparison based process'' and of �process isomorphism up-to process identifiers''. The Key Lemma is proven which states that comparison based processes which are isomorphic up-to PIds behave very similarly, if the PIds in the processes in their enviromnents are what is called order equivalent.

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W.O.D. Griffioen, and M. Huisman. * A Comparison of PVS and Isabelle/HOL. *Technical report: CSI-R9810, March, Radboud University Nijmegen, 1998.

There is an overwhelming number of different proof tools available and it is hard to find the right one for a particular application. Manuals usually concentrate on the strong points of a proof tool, but to make a good choice, one should also know (1) which are the weak points and (2) whether the proof tool is suited for the application in hand. This paper gives an initial impetus to a consumers' report on proof tools.The powerful higher-order logic proof tools PVS and Isabelle are compared with respect to several aspects: logic, specification language, prover, soundness, proof manager, user interface (and more). The paper concludes with a list ofcriteria for judging proof tools, it is applied to both PVS and Isabelle.

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F.A. Grootjen. * NLCA: Towards an algorithmic implementation. *Technical report: CSI-R9811, University of Nijmegen, 1998.

In most mainstream approaches to natural language modelling, some form of hierarchical structure (e.g. phrase structure) plays a central role. However, practical application of phrase structure-based parsers in natural language processing has enjoyed only limited success. One reason for this lies in the rigidity of hierarchical structure on the one hand, as opposed to the high flexibility of language use on the other. The relative lack of success of rule-based parsers has inspired a search for alternative methods, such as statistically based or lexicon-driven parsing.

In search for a solution the NLCA project took one step back, and examined the nature of hierarchical structure in general, and phrase structure in particular. It looked for ways to derive hierarchical structure from input, and to incorporate it in a mathematically well-founded theory of knowledge representation. The result is an approach in which hierarchical structure is found as the yield of the interaction between different, inherent combinatorial properties of linguistic units. The model identifies three different basic relations that underlie these combinatorial properties, at a level of abstraction that, in principle, allows language-independent modelling and analysis. The structural analysis of input is mapped onto formal concepts in the sense of lattice theory and in this way creates a suitable environment for information retrieval.

This paper summarises the basic ideas of NCLA and presents a sketch of an algorithm that implements NLCA for the English language.

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B.P.F. Jacobs, J.A.G.M. van den Berg, M. Huisman, M. van Berkum, and U. HenselH. * Reasoning about Java Classes. *Technical report: CSI-R9812, April, Radboud University Nijmegen, 1998.

We present the first results of a project called LOOP, on formal methods for the object-oriented language Java. It aims at verification of program properties, with support of moderntools. We use our own front-end tool (which is still partly underconstruction) for translating Java classes into logic, and aback-end theorem prover (namely PVS, developed at SRI) forreasoning. In several examples we will demonstrate how non-trivial properties of Java programs and classes can beproved following this two-step approach.

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H. Dierks, A. Fehnker, A. Mader, and F.W. Vaandrager. * Operational and Logical Semantics for Polling Real-Time Systems. *Technical report: CSI-R9813, April, Radboud University Nijmegen, 1998.

PLC-Automata are a class of real-time automata suitable to describe the behaviour of polling real-time systems.PLC-Automata can be compiled to source code for PLCs,a hardware widely used in industry to control processes.Also, PLC-Automata have been equipped with a logical and operational semantics, using Duration Calculus (DC) and Timed Automata (TA), respectively.The three main results of this paper are:(1) A simplified operational semantics.(2) A minor extension of the logical semantics,and a proof that this semantics is complete relative to ouroperational semantics. This means that if an observable satisfies all formulas of the DC semantics, then it can also be generated by the TA semantics.(3) A proof that the logical semantics is sound relative to ouroperational semantics. This means that each observable that is accepted by the TA semantics constitutes a model for all formulas of the DC semantics.

F.A. Grootjen, V. Kamphuis, and J.J. Sarbo. * A Genealogy of Phrase Structure. *Technical report: CSI-R9814, University of Nijmegen, 1998.

In standard approaches to NLP phrase structure is usually specified by a grammar. The coverage of such a grammar, especially in the case of performance data is often insufficient; the grammar is subject to frequent modifications and this can bring about maintainabilitu problems. In this paper we describe a releational basis underlying phrase structure. Based on that, a model is defined that yields hierarchical structure as the result of more abstract principles related to the combinatorial properties of linguistic units. The model is simple in use and easy to maintain, and provides an important key to the description of non-phrase structure configurations that require greater flexibility.

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V. Kamphuis, and J.J. Sarbo. * NLCA - A truly relational model of language. *Technical report: CSI-R9815, May, Radboud University Nijmegen, 1998.

The primary goal of Natural Language Concept Analysis (NLCA) is to find a means of handling flexibility in natural language. Contrary to traditional approaches using the part-whole paradigm (e.g. phrase stucture grammar), NLCA identifies a relational basis underlying hierarchical structure. This basis derives from the interaction of lexical items due to their inherent combinatorial properties, and constitutes a set of three relation schemes: major predication, minor predication and qualification. A comparison between NLCA and dependency-based description reveals their common basis in word-based modellig, but shows fundamental differences in their foundation.

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A.L.J. van den Hoogenhof. * The maturity of object-oriented methodologies. *Technical report: CSI-R9818, July, Radboud University Nijmegen, 1998.

Methodologies within software engineering are introduced with the speed of improved soap-powders. One of the major movements is object-orientedness. It already started at language level long ago, with Simula 67 and Smaltalk, and nowadays many methodologies are labelled as object-oriented. And it is ongoing: unifications of object-oriented methods are introduced to get the maximum benefit of all involved. This article examines som important techniques and constructions used in the mainstream object-oriented methodologies, and elaborates on their common properties and weaknesses in practical use.

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Th.P. van der Weide, and P. van Bommel. * Individual and collective approaches for searcher satisfaction in IR. *Technical report: CSI-R9819, Information Systems Group, Computing Science Institute, University of Nijmegen, The Netherlands, 1998.

The incremental searcher satisfaction model for Information Retrieval has been introduced to capture the relevancy of documents under consideration of documents previously presented. In this paper, different approaches for the construction of increment functions are identified, such as the individual and the collective approach. The requirements posed by these approaches are examined and evaluated with respect to well-known similarity measures used in IR, such as Inclusion, Jaccard's, Dice's, and Cosine coefficient.

B.C.M. Wondergem, P. van Bommel, and Th.P. van der Weide. * Association Index Architecture for Information Brokers. *Technical report: CSI-R9820, July, University of Nijmegen, 1998.

Information Discovery (ID) is the synthesis of Information Retrieval (IR) and Information Filtering (IF). In ID, broker agents act as intermediaries between user agents and source agents. Information about user interests and documents in sources can be modeled by 2-level hypermedia representations. These representations allow navigational mechanisms which have proven their effectiveness in IR applications. Broker agents should thus combine two 2-level hypermedia representations to obtain an overall information structure necessary for the synthesis of IR and IF. For this, we propose the so called Association Index Architecture (AIA) which consists of two 2-level hypermedia representations which are connected through a third level which is coined the association index. The AIA thus forms a 3-level hypermedia representation. Broker agents can perform actions in the AIA to implement their IR and IF related tasks. The AIA is shown to be a general symbolic architecture for combining knowledge by illustrating how a number of ID applications can be performed in it.

J. Romijn, and J. G. * Exploiting Symmetry in Protocol Testing. *Technical report: CSI-R9821, September, Radboud University Nijmegen, 1998.

Test generation and execution are often hampered by the large spaces of the systems involved. In automata (or transition system) based test algorithms, taking advantage of symmetry in the behavior of specification and implementation may substantially reduce the amount of tests. We present a framework for describing and exploiting symmetries in black box test derivation methods based on finite state machines (FSMs). An algorithm is presented that, for a given symmetry relation on the traces of an FSM, computes a subautomaton that characterizes the FSM up to symmetry. This machinery is applied to Chow�s classical W-method for test derivation Finally, we focus on symmetries defined in terms of repeating patterns.

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Detlef Plump. * Term Graph Rewriting. *Technical report: CSI-R9822, September, Radboud University Nijmegen, 1998.

Term graph rewriting is concerned with the representation of functional expressions as graphs, and the evaluation of these expressions by rule-based graph transformation. Representing expressions as graphs allows to share common subexpressions, improving the efficiency of term rewriting in space and time. Besides efficiency, term graph rewriting differs from term rewriting in properties like termination and confluence. This paper is a survey of (acyclic) term graph rewriting, where emphasis is given to the relations between term and term graph rewriting. We focus on soundness of term graph rewriting with respect to term rewriting, on completeness for proving validity of equations and for computing term normal forms, on termination and confluence, and on term graph narrowing.

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S. van Dreumel, and J.I. Potjer. * De Amazon Grammatica. *Technical report: CSI-R9823, September, Radboud University Nijmegen, 1998.

The underlying report contains the Amazon grammar documented in Dutch.The Amazon grammar describes the surface-structure of Dutch sentences, based upon the five parts of a Dutch sentence (the places for topicalisation, verb-second, arguments, verb cluster and extraposition) and the description of constituents. The grammar is written according to the technolinguistic method, meaning that all rules used are explicitly based upon linguistic principles only, i.e. linguistic theory has been separated from the algorithm.Started out in the 70s as an interactive syntax-embeddedSNOBOL-program, Amazon now consists of a documented Latex-embedded AGFL-grammar. The formalism used (Affix Grammars over a Finite Lattice) offers advantages like the separation of grammar and algorithm, the use of affix-lattices and the on-the-fly computation of affix-values.Apart from linguistic improvements and extensions, the main differences with the previous version of Amazon are: modularisation, extended documentation, standardisation of the terminology and addition of robustness for ungrammatical sentences and unknown words or constructions.

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M.C.A. Devillers. * An LSL to PVS Compiler. *Technical report: CSI-R9824, October, Radboud University Nijmegen, 1998.

A compiler which translates axiomatic specifications written in the Larch Shared Language (LSL) to theories of the Prototype Verification System (PVS) is described by means of examples. Besides giving an equivalent axiomatic specification in PVS, the compiler enables one to check that an LSL specification has a model in the higher-order logic of PVS.

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P.A. Jones, C.H.A. Koster, P. van Bommel, and Th.P. van der Weide. * Critical Reference Counting. *Technical report: CSI-R9825, Information Systems Group, Computing Science Institute, University of Nijmegen, The Netherlands, 1998.

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B.C.M. Wondergem, P. van Bommel, and Th.P. van der Weide. * Boolean Index Expressions for Information Retrieval. *Technical report: CSI-R9827, December, University of Nijmegen, 1998.

Keywords still seem to form the basis for document content and query representation. Approaches to use more advanced linguistic structures, such as noun phrases, still are in an experimental phase. In addition, Boolean descriptor languages have often been applied for Information Retrieval. However, the synthesis of logic and linguistics in one descriptor language still is an open issue. In this paper, Boolean index expressions, combining Boolean logic and linguistic structure, are proposed as a good balance between expresiveness and practical issues. Boolean index expressions are obtained by augmenting regular index expressions with logical operators for disjunction, conjunction, and negation. Boolean index expressions are more expressive than both index expressions and the Boolean query language based on keywords. They allow a compact representation of logical combinations of index expressions. In addition, Boolean index expressions are still efficiently parsible and their meaning can be deter- mined through their structure. It is shown how Boolean index expressions can be brought into normal form, allowing fast numerical matching. Matching strategies for Boolean index expressions are obtained by adapting matching strategies for index expressions by providing a case for negations. Our implementation of Boolean index expressions illustrates mentioned issues.