ISSN Volume 17, number 6 December, EDITORIAL ADDRESS BNVKI newsletter

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1 ISSN Volume 17, number 6 December, 2000 BOARD BNVKI: Joost Kok (chair) Rineke Verbrugge (member) Wiebe van der Hoek (member) Yao-Hua Tan (member) Floris Wiesman (member) Luc DeHaspe (member) Walter Daelemans (member) Bas Zinsmeister (member) EDITORIAL BOARD: Floris Wiesman (Editor in Chief) Jaap van den Herik Bart de Boer Shan-Hwei Nienhuys-Cheng Cees Witteveen Antal van den Bosch (section editor) Joris Van Looveren (editor Belgium) Richard Starmans (section editor) Radboud Winkels (section editor) BNVKI-SECRETARY EDITORIAL ADDRESS BNVKI newsletter Rineke Verbrugge Joke Hellemons Rijksuniversiteit Groningen Universiteit Maastricht Cognitive Science and Engineering FdAW, Department of Computer Science Grote Kruisstraat 2/1 P.O.Box 616, 6200 MD Maastricht 9712 TS Groningen Telephone: / rineke@tcw2.ppsw.rug.nl Fax: newsletter@cs.unimaas.nl unimaas.nl/~bnvki

2 Editorial BNVKI Newsletter 128

3 TABLE OF CONTENTS (Editor-in-Chief)... Table of Contents... BNVKI-Board News (Joost Kok) Section Computational Linguistics (Antal van den Bosch) SIKS (Richard Starmans)... Section Knowledge Systems in Law and Computer Science (Radboud Winkels) Call for Papers Conferences, symposia, Workshops... addresses, Board Members/ Editors BNVKI newsletter / How to become a member?/ Submissions... Advertisement... The BNVKI is sponsored by AHOLD and by BOLESIAN In 2000, the publication of the BNVKI newsletter is also supported by the Division of Computer Science Research in the Netherlands (previously called SION, now ACI) BNVKI 129

4 BNVKI- BOARD NEWS Joost Kok NEURAL NETWORKS 1 Report by Bert Kappen Katholieke Universiteit Nijmegen SpikeProp: Backpropagation for Networks of spiking neurons S.M. Bohte, H. La Poutré and J.N. Kok This session contains three contributions on neural networks. The presentations are as diverse as the field of neural networks itself the first contribution has a neurobiological motivation, the second paper discusses cognitive aspects and the third paper treats the neural network as a statistical tool. Backpropagation is a well-known learning rule for feed-forward neural networks. A shortcoming of these networks is that neural activity is modelled as rate coding. Instead, more and more neurophysiological evidence indicates that the exact timing of spikes is also of importance or information processing in the brain. This paper presents an extension of the Backpropagation learning rule for spiky (integrate-and-fire) neurons. Trading off perception with internal state reinforcement learning and analysis of Q-Elman Networks in a markovian task Bram Bakker and G. van der Voort van der Kley There is a long experimental tradition in experimental psychology on measuring reaction times of subjects performing various tasks. From these studies it has become clear that the time to execute a task increases with task complexity. This suggests that complex tasks are implemented as the sequential execution of elementary steps. In a simplified way, these elementary steps may be thought of as hardwired feed-forward neural networks. This paper demonstrates that the Elman network behaves in the above way. An Elman network is a feed-forward network augmented with delayed feedback connections from the hidden layer to the input layer. Therefore, the Elman network can implement tasks either as an elementary feed-forward step or as a sequence of such steps. The paper demonstrates that the Elman network learns the parallel (simply feedforward) BNVKI newsletter 130

5 solution for simple tasks and chooses the sequential solution when the task complexity increases. Thus, the behaviour of the Elman network is similar to the neural network human. In addition, it shows that although some tasks can in principle be solved by a pure feed-forward implementation, the sequential solution provides a simpler alternative. Ensembles of nonconformist neural networks M.C. van Wezel, M.D. Ont, and W.A. Kosters This paper shows a scheme for training an ensemble of feed-forward neural networks. It is well-known, that the expected prediction error of the mean output of an ensemble is smaller than the mean prediction error of the outputs of each of the individual networks in the ensemble. The difference is proportional to the diversity among the networks in the ensemble. The diversity can be measured by the covariance in the network outputs over the training set. The authors propose to stimulate diversity during training by adding the covariance to the training error, and performing gradient descent on this cost criterion. Numerical results indicate improvement over training the networks independently. KNOWLEDGE REPRESENTATION AND SYSTEMS Report by Frank van Harmelen Vrije Universiteit Amsterdam The Law as a dynamic interconnected system of states of affairs J. Hage and B. Verhey Jaap Hage and Bart Verheij from the University of Maastricht presented a (very) abstract model of the law. The purpose of this model is to serve as a toplevel ontology of the law. Much existing work on legal ontologies (e.g. by McArty, by Valente, etc) can then be presented as specialisations of this very general top-level legal ontology. The basic modelling primitives of their ontology are states of affairs, with events connecting these states, possibly governed by rules. The authors showed how a number of existing legal concepts and scenario s can be modelled in such a very general ontology.your reporter liked the general aim of the paper (i.e. providing a top-level ontology to unify various existing more detailed ontologies), but wondered whether the proposed primitives (states, events, and rules) were not so general that this would cover almost any domain. Perhaps more commitment to more law-specific concepts would make modelling with the proposed ontology easier? Towards a generic model of trust for electronic commerce Y.H. Tan and W. Thoen This first of two contributions in this session from the Erasmus Universiteit consisted of two halves: in the first halve, the authors presented a general analysis of the notion of trust. They discussed different definitions of trust, culminating in their own definition of level of trust. They distinguished different types of trust and different mechanisms for trust. In the second half of the presentation, they provided a formal analysis of a particular trust scenario, namely the mechanism for creating trust in the shipping industry via bills of lading. Unfortunately, the formal analysis was limited to this particular case. An obvious agenda for further work is to provide a formal account of trust that is as general as the informal analysis in the first part of the presentation. DocLog: an electronic contract representation language Y.H. Tan and W. Thoen The same two authors presented a rather different type of work, namely one aiming at a machine readable representations of legal documents. In itself this is nothing new, but the approach in this paper was innovative because it distinguished different levels at which to represent such a legal document: a data-layer, which aims at the kind of representation typically used in ERP systems. a natural language layer, that contains the text of the document structured by a predefined set of XML tags. a semi-formal layer, using concepts like agents, actions, and norms to describe the semantics of the legal document in a machine processable form. Clearly, such multi-layered, partly machine accessible representations of legal documents have a great potential in many application areas. NATURAL LANGUAGE PROCESSING 2 Report by Walter Daelemans Universiteit Antwerpen The organizers of BNAIC 2000 have done a great job in making the conference attractive for computational linguistics researchers, for example by inviting Yorick Wilks as keynote speaker (unfortunately he didn t make it because of illness), BNVKI newsletter 131

6 and by devoting two sessions to NLP work. In the second of these, Bart de Boer, a previous BNVKI award winner, could not present his paper, unfortunately. An analysis of multiple-word naming games J. Van Looveren This works builds incrementally on the groundbreaking work on lexicon evolution in populations of agents playing naming games, undertaken at the AI-LAB in Brussels. In this particular study, it was shown that the general approach still holds when allowing the communicating agents to use expressions consisting of more than one word. This results in smaller lexicons and does not decrease communicative success in the population. Efficient parsing of domain language K. Sima an This paper describes part of the dissertation research of Khalil Sima an, a dissertation for which he received the FoLLI Outstanding Dissertation Award, recently. He received the BNVKI award for his paper at the BNAIC as well. Given all these honours, I can only advise you to read at least the paper, preferably also the dissertation, for yourself. In his research, Sima an shows that broad-coverage grammars and statistical parsers can effectively be specialised to specific domain language, making the statistical model considerably smaller and more efficient, without substantial loss in accuracy. MACHINE LEARNING 4 Report by Ida Sprinkhuizen-Kuyper Universiteit In this session three papers on datamining techniques were presented. Classification and Target Group Selection based upon Frequent Patterns W. Pijls and R. Potharst This talk reported on research inspired by association rules. The conclusion of the paper is that the methods introduced especially result in transparent results: it is easy to state why an object is classified as it is, or why an individual is selected in a mailing group. This is an important aspect for practical applications of datamining. Data Fusion: A Way to Provide More Data to Mine in? P. van der Putten The speaker showed how to combine a customer database (many customers, not so many variables) and a market survey (not so many people, but many variables) in order to extend the customer database to predict the behaviour of the customers on variables not in the customer database, but important for a datamining task. His first results are promising. Fuzzy Clustering Based Target Selection U. Kaymak and M. Setnes The method of extended fuzzy c-means clustering was described and applied on two cases with real-world data. Gain charts showed the effect of the clustering on the target selection. Also this talk and paper concluded with remarking the transparency of the obtained profiles. The paper makes a solid impression. LOGIC AND REASONING 1 Report by Bart Verhey Universiteit Maastricht Semantics of Input-Consuming Logic Programs A. Bossi, S. Etalle and S. Rossi The abstract was presented by Sandro Etalle, who works at the IKAT institute of the Universiteit Maastricht. The full paper was presented at CL2000, the First International Conference on Computational Logic, and deals with input-consuming logic programs. Such logic programs are a special kind of moded programs. A logic program is moded when the arguments of the atoms are labelled as input or output ones. Input-consuming programs are then those moded programs in which the derivation steps are exactly those for which the input arguments are not instantiated by unification with the clause's head. The authors proved that the operational semantics of the inputconsuming resolution rule is correct and BNVKI newsletter 132

7 complete with a particular denotational semantics for logic programs, and investigated properties of that semantics. The context of the work is the use of socalled delay declarations, that are used to avoid nontermination and inefficient computation that can result from dynamic rule selection. Relating Protocols for Dynamic Dispute with Logics for Defeasible Argumentation H. Prakken The paper, to appear in Synthese, deals with disputes in which arguments and counterarguments are exchanged. A way of evaluating the arguments used in such disputes is in terms of games: the proponent of an argument for a claim must have a winning strategy. The author discusses how this evaluation criterion is affected when the body of information is not fixed at the start of the debate. The author defines notions of soundness and fairness for the protocols underlying such dynamic disputes. In the talk, the focus was on some of the author's other work, focusing on the speech acts involved in disputes. Classical and General Frameworks for Recovery W. van der Hoek and C. Witteveen The paper, that appears in the proceedings of ECAI2000, the 14th European Conference on Artificial Intelligence, deals with theory recovery. The idea is that the consistency of a theory is restored with respect to an intended semantics. In the authors' approach, a second semantics, the backup semantics, is used to guide the process of recovery. In the process, the theory that is not interpretable in the intended semantics, is replaced by an interpretable theory that has the same meaning from the point of view of the backup semantics. In previous work, the focus was on theories that were at least classically consistent. In contrast, the present paper allows classically inconsistent theories and deals also with classical logic as the intended semantics. The abstract was presented by Cees Witteveen, who informed the audience that the full paper contains an error with respect to its relation with the AGM framework of theory revision. MACHINE LEARNING 2 Report by Hendrik Blockeel Katholieke Universiteit Leuven An Initial Approach to Wrapped Input Selection using Least Squares Support Vector Machine Classifiers: Some Empirical Results B. Baesens, S. Viaene, T. van Gestel, J.A.K. Suykens, G. Dedene, B. de Moor and J. Vanthienen In the first talk of this session, Bart Baesens presented a machine learning approach in which two learning techniques are combined: the use of least squares support vector machines (LS-SVMs) and of wrapped feature selection. LS-SVM's are a modification of the standard support vector machines. The distinguishing feature of LS-SVMs is that the error function that is minimised is the sum of squared errors instead of the sum of absolute errors; this gives rise to a more efficiently solvable system of equations and hence ensures a better scalability. Wrapped feature selection refers to a feature selection approach that involves a greedy search for a minimal subset of features that allows to train LS-SVMs with an estimated predictive performance not significantly worse than the one achieved by an LS-SVM using all features; this estimation is done using crossvalidation. Experimental results on several benchmark datasets were presented that show the value of this approach. A Unified Approach for Practical Applications of Fuzzy Clustering U. Kaymak Uzay Kaymak talked about fuzzy clustering, which differs from normal clustering in that elements not necessarily belong to a single cluster, but instead are assigned some degree of membership of several clusters. One fuzzy clustering algorithm is the socalled "fuzzy-c-means" algorithm. Dr. Kaymak discussed several problems with this algorithm, such as its tendency to behave suboptimally when used with highly skewed data distributions, and the fact that a good choice for the number of clusters c must be made in advance. He then presented an extended fuzzy c-means (EFCM) algorithm, which has the property that during the clustering process clusters that are highly similar may be merged, and BNVKI newsletter 133

8 also uses an extended notion of prototypes of clusters. The EFCM algorithm was demonstrated to work better than FCM on several example data sets. Rough Sets and Ordinal Classification J.C. Bioch and V. Popova Viara Popova presented an approach to ordinal classification (the learning of monotone classification functions) that is based on rough sets. After introducing the audience to some concepts of rough set theory, she showed how this theory can be extended to cater for ordinal classification by defining monotone versions of existing concepts such as discernibility matrix, and reducts. She proceeded by presenting some existing results on the use of monotone discrete functions for ordinal classification, and then presented several theorems that clarify the relationship between monotone discrete functions and monotone rough set concepts. The talk ended with a brief discussion of experiments that support the theoretical results. GRAPHICAL MODELS Report by Mehdi Dastani Vrije Universiteit Amsterdam Bayesian Model-Based Diagnosis P. Lucas This session began with Peter Lucas who presented an extension of the model-based diagnosis framework. According to him, traditional consistency-based diagnosis systems do not provide appropriate representation to deal with the involved uncertainty when they generate diagnosis. On the other hand, Bayesian networks, designed to represent and reason about uncertainties, are not appropriate to represent and reason about the structure and the behaviour of systems. The presented framework, called Bayesian model-based diagnosis, is a way to integrate both logical and probabilistic reasoning to determine and generate diagnosis. In such a framework, it can be reasoned about the structure and the behaviour of systems while the involved uncertainties are taken into account. Propagation of Multiple Observations in Qualitative Probabilistic Networks S. Renooij, L.C. van der Gaag, and S. Parsons The second speaker was Silja Renooij who presented a paper on qualitative probabilistic networks. She explained that this type of networks is used to represent knowledge in terms of observables and their probabilistic relations. The existing algorithms to determine the effects of observables on each other can only handle a single observation appropriately. A single observation is entered and propagated through a qualitative probabilistic graph and the effect of the observation is determined. The standard way to deal with multiple observations is by entering them in sequential order. However, the order of entering observables yields different and weaker results. The authors proposed an algorithm to propagate multiple observations in qualitative probabilistic networks such that the order of observations does not generate weaker results. This is done by disregarding the so-called intercausal influences. The speaker demonstrated their algorithm by working out an example. Variational Approximations Between Mean Field Theory and the Junction Tree Algorithm W. Wiegerinck The last speaker of this session was Wim Wiegerinck who presented a method for approximate reasoning in graphical models such as Bayesian networks. He argued that the exact reasoning in large and complex graphical models is computationally intractable and that approximate reasoning is therefore essential. Large, complex and intractable graphical models are approximated by models with tractable structures. To this end, he proposed an extension of mean field method by using approximating model that factorises according to given structure such as potential clusters. In this way, he claims to bridge between mean-field theory and exact computations. This method is presented by some examples. INFORMATION BROKERING Report by Yao-Hua Tan Erasmus Universiteit Small-World Semantic Networks E. Postma and F. Wiesman In their research Eric Postma, Floris Wiesman and Jaap van den Herik studied semantic networks for knowledge representation. Semantic networks consist of conceptual nodes and association links between these nodes. Knowledge is retrieved from these networks by using these association links between the nodes that connect concepts to related concepts. For example, by having a direct link BNVKI newsletter 134

9 between Newton and apple, the person Newton is directly associated with the apple that supposedly led to the invention of the gravitation law. In their research they studied the problem what the characteristics are of an efficient semantic network. Based on some fundamental results from graph theory they postulated that the so-called small-world networks are the most efficient ones. Small-world networks are networks that are subdivided in smaller densely connected sub-networks with relatively few links between these sub-networks. They validated these results with a comparison between a natural human network and an artificial man-made network. The human network was a database of word association as produced by free association of human test persons. The man-made network was the ARIA database of the Amsterdam Rijksmuseum that was developed to classify the art objects in the collection of this museum. Interestingly, the human network had a larger small-worldliness than the manmade network, which seems a corroboration of their conclusion about the efficiency of small-world networks. ICEBERG: Exploiting Context in Information Brokering Agents C. Jonker and A. Vollebregt Catholijn Jonker reported research that she had done jointly with Arjen Vollebregt on the development of an information broker that assists the user in finding personal development courses. The problem in this domain is that people can have a wide variety of perspectives on these courses. For example, a question to learn how to give a presentation might be either a request for a course on how to use PowerPoint software to prepare a slide presentation, or a request how to cope with the stage fright. The information broker should be able to handle both questions, hence it has to store the data about courses from many different perspectives. The Iceberg architecture is a kind of multidimensional database that is modelled in the DESIRE framework. The Iceberg system uses a taxonomy of types to assist the user in finding the right search terms. Based on the reasoning process of the user the Iceberg system can narrow down questions, or broaden the scope of a question to generate alternative solutions that could help the user to formulate his questions more precisely. For example, when the user asks for a course how to learn how to give presentations, the system could reply by asking whether it is for preparing slides or how to cope with stage fright. The DESIRE framework is very suitable to model this reasoning process of the user, because it is based on a collection of autonomous reasoning modules that can simulate the human reasoning. After the presentation Jonker also gave a demonstration of the system. KNOWLEDGE REPRESENTATION AND SYSTEM 2 Report by Jaap van den Herik Universiteit Maastricht The session consisted of three presentations treating different aspects of the theme. The speakers presented their knowledge well and in an animated way. They neatly kept the time schedule and raised an interesting discussion. The first speaker was Frank van Harmelen (Vrije Universiteit Amsterdam). He is co-author of the publication Oil in a Nutshell, written by D. Fensel, I. Horrocks, F. van Harmelen, S. Decker, M. Erdmann and M. Klein. One month earlier the SIKScommunity had already been extensively informed on the propositions for standardization of this illustrious team (beside the VU Amsterdam, the Universities of Manchester, Karlsruhe and Stanford are represented in the consortium). Van Harmelen first explained why we need a uniform standard for the description of ontologies. Thereafter, issues were addressed as to how should we describe an ontology in a standard way? BNVKI newsletter 135

10 What are the common aspects and what can be exchanged? The team proposes to come to an OIL, i.e., an Ontology Interchange Language. OIL works with the well-known modelling primitives from the frame-based world and is based on the ontologies that are Description Logic oriented. Furthermore, it is an extension of the Web standards XML and RDF. In his talk Van Harmelen addressed both the syntactical and semantic aspects. Neither did he forget practice. If we may believe his enthusiastic presentation OIL will be the standard of the future (for ontologies). From a political point of view Van Harmelen and his group have ensured themselves of renowned support. Moreover, the concepts shown are convincing. The floor is now to the users. Model-based diagnosis support for satellitebased instruments André Bos The co-authors were Arjen van Gemund en Cees Witteveen (all three of the Delft University of Technology). The Delft group has ample experience with modelbased monitoring and the diagnosing of a satellite-based instrument. In the course of their research they have come to the conclusion that there are two explicit problems which recur repeatedly, i.e., the complexity and the testframe. The group therefore decided to improve the support of the diagnosis by a special support tool named UpTime. This tool contains a large number of detailed component descriptions that link up to the model-based diagnoses. Obviously, a hierarchy has been made in the components. This also reduces the complexity that occurs when, in a certain situation, a component has to be investigated more closely before use. In short, the tool clearly simplifies the process of argumentation, but unfortunately at the expense of the model management. Several descriptions of behaviour of the model have to be maintained and also linked to each other, but not by the logical hierarchy with which the components are connected to each other. Bos addressed this problem in his talk and also gave an answer to a question on this subject. He did not have a solution, but the problem did have the attention of the research group. Ben Kröse (Universiteit van Amsterdam) gave the last presentation of this session. His co-authors, Rob van den Boogaard and Niek Hietbrink, are from the same University. Their publication is titled: Programming robots is fun: Robocup Jr During the RoboCup Euro 2000 the group of Kröse organized a tournament for schools, in which they used robots made of LEGO. They called this tournament: Robocup Jr. The idea was borrowed from Henrik Lund and Luigi Pagliarini, who organized the first tournament in 1999 during the RoboCup 99 (Stockholm). The idea is to have school children (13-16 years) gain experience in programming robots. In this talk (and in the publication) various educational aspects were discussed, and the reasons why something was done and why something else not, were weighed against each other (e.g., the use of LEGO light sensors in stead of the use of a camera). We will limit the description here to some realized facts, because these will show best the success of the whole project and also the enthusiasm with which the group has organized the Robocup Jr. Twelve teams of 8 schools participated (11 Dutch teams and 1 German team), consisting of approximately 50 children. In the morning a general introduction was given and in the afternoon the children could work on the robot. There was one teacher for three groups. Especially the children with some fear for programs and programming quickly (in 15 minutes) lost their diffidence. The presence of the assignments : Find the ball, Make a sound, Look for the ball, made it easier for the pupils (certainly the beginners group) BNVKI newsletter 136

11 to learn how to program. Unfortunately, I nowhere read in the description: Kick the ball, or Shoot the ball in the goal. Neither did I hear this in the presentation. But the fact that Ben Kröse, who cheered up the talk with a film of very active children playing robot football, told that there was a winner (Montessori Lyceum Amsterdam), several goals must have been scored. The winners received a LEGO Mindstorms set which was again an encouragement to continue activities and publications in this direction. The BNAICaudience heard/read with pleasure that the second place was won by a very simple program, that was not hindered by knowledge but benefited from the speed (of the loops) and was therefore often first at the ball. In summary, here we see a nice educational opposite between knowledge (and the obstacles to deal with it properly) and rapid search (with little knowledge). The advice of Kröse cum suis to call this field edutainment is gladly taken over and we hope that the industry and academia will continue to support it. BNVKI newsletter 137

12 LOGIC AND REASONING 2 Session Chair H.C.M. de Swart Reasoning with Modularly Pointwise Preferential Relations O. Arieli In this longer contribution the author considers a family of preferential consequence relations, defined by a general and natural semantics. The common property shared by all these relations is that their underlying preference criteria are based on modular partial orders. These relations share many desirable properties for common-sense reasoning, such as paraconsistency, plausibility, adaptivity and rationality. Input-Output Logics L.W.N. van der Torre Roughly speaking, there are two kinds of black boxes. The box may stop some inputs, while letting others through, perhaps in modified form. And inputs may be conditions, with outputs expressing what is deemed desirable in those conditions. The purpose of this short contribution is to develop a general theory of propositional input/output operations, covering both kinds of examples. Particular attention is given to the case where outputs may be recycled as inputs. Learning in Description Logics by Refining Concepts Shan-Hwei Nienhuys-Cheng Since Description Logics (DL) are a fragment of first-order logic, one could in principle translate DL expressions into prenex conjunctive normal form (PCNF) and use the PCNF-refinement operator to refine the PCNF encoding of DL expressions. The author explains that this straightforward approach has two disadventages. In order to circumvent these problems, the author develops a refinement operator working directly on DL formulas. Since there exists no complete and minimal refinement operator, the operator proposed by the author is one of the best one can hope for. PLANNING AND SCHEDULING Session Chair Ton Weijters After disentangle some communication problems between notebooks and beamers the planning and scheduling session started with the two planned presentations. YongPing Ran presented the first paper originating from the Knowledge and Agent Technology group of Maastricht with the title Approximation of the optimal solution for Dynamic CSPs. Many AI problems can be modelled as constraint satisfaction problems (CSPs). However, the CSP problem definition may change over time because of the environment, the user preference or agent s behaviour in a distributed system. After a change the infringed solution must be repaired. A Repair-Based algorithm with arcconsistency (RB-AC) is available. However, the time complexity RB-AC is higher than that of an algorithm that constructs a solution from scratch. In the presentation (and the paper) two alternative algorithms that modify the original RB-AC algorithm are proposed. Experimental results show the two proposed algorithms perform better with respect to the approximation of the optimal solution in a limited period of time. A very clear presentation, but maybe an improvement is possible by adding one or more practical relevant examples to demonstrate the basic ideas and the usefulness of the two proposed repair algorithms. The second presentation An Approximation Algorithm for a Logistic Planning Problem from the Information Technology and Systems faculty of the University of Delft deals with a logistic planning problem. However, this logistic problem is (nearly) decomposable into a number of subproblems. The research question is a more or less traditional: how well can this (planning) problem be solved by iteratively scheduling the local problems according to a certain scheduling policy. An algorithm designed as a multi-agent system that uses a specific policy to solve the logistic problem was explained an approximation results were presented. The time improvements were very impressive. The plan quality comparison is less clear because the Black-box approach optimise for a minimum amount of time steps, the presented approach optimise for the plan length. However, the quality of the plans seems good compared with the Black-box approach. Because the local approximation algorithms are still NP-hard, an open question seems the performance of the new approach on more complex real-world problems. BNVKI newsletter 138

13 In conclusion, two fine presentations combined with some clarifying discussions. BNVKI newsletter 139

14 ISCL 2000 International Summer School in Computational Logic Acquafredda di Maratea, Basilicata September Marco Gavanelli DIF - University of Ferrara mgavanelli@ing.unife.it Paolo Torroni LIA - DEIS - University of Bologna ptorroni@deis.unibo.it ISCL 2000, the International Summer School in Computational Logic held at Acquafredda di Maratea, Basilicata (Italy) on September, 3 rd -8 th, 2000, represents the prosecution of the biennial summer schools organized by GULP, the Italian association for Logic Programming established in 1987 in Pisa, Italy (two former schools had been held in 96 and 98). This year s edition opened to an international perspective thanks to the auspices of ALP, the Association for Logic Programming, and of COMPULOG, the ESPRIT Network of Excellence in Computational Logic. Computational Logic constitutes nowadays a foremost research stream. Glaring achievements of the most recent years range from Constraint Logic Programming to Internet applications and verification techniques, where solid mathematical foundations allowed dealing with more and more complex problems. The school organizers, Sandro Etalle and Maurizio Gabbrielli, decided to give it a strong characterization with respect to new technologies and applications of Logic Programming, still leaving an adequate margin to more fundamental and theoretical issues. The school counted 25 participants, mostly from academic research areas: half of them were Italian, the others came from France, Spain, Estonia, Japan, Israeli, UK, Russia, Czech Republic, Sudan. In general, the courses were very high level, and covered a wide range of topics. ISCL 2000 was composed of six lectures of seven hours each, with the possibility of proficiency grades at the end for those interested. The first day was devoted to the course presentations. The lectures had a large participation, despite the tight scheduling (eight hours per day). An application oriented course was held by Paul Tarau (Logic Programming and Internet Technologies), where through the description of several development tools it has been shown how Logic Programming can be used to create Internet applications (HTML, VRML, CGI) and to deal with technologies such as multicast, fluents, and for rapid agent system prototyping. Frits Vaandrager s lectures on Verification of Timed and Hybrid Systems concentrated on the use of timed automata technology for model checking and on hybrid systems. Again, a tool was used to demonstrate the practicality of some issues. Peter Lee gave a lecture on Proof-Carrying Code: a mechanism for certifying the safety of a program supplied by an untrusted source. Such mechanism uses a language of predicates to express the verification conditions and the specification of inference rules: in this way an interesting link was set between the high level specifications and the low level code (assembler for x86). More formal courses were held by Dale Miller (A Logic for Reasoning about Logic Specifications) on linear logic and sequent calculus, and by Moreno Falaschi (Optimization of Declarative Languages), who gave an overview on Functional Logic Programming (FLP), partial evaluation and static analysis of functional logic programs based on abstract interpretation techniques. Finally, Thom Fruehwirth, (Constraint Programming and Reasoning) discussed with wealth of practical examples the fundamentals of Constraint Logic Programming (CLP), Concurrent-CLP, and Constraint Handling Rules (CHR), which allow one to define declaratively new constraints propagation method. The deep level of detail used to explore certain issues did not let loose sight of the general framework that was being depicted: the lecturers themselves had care to stress the connections holding among the different topics. In this way, both the novice and the more experienced students benefited from participating. The organization has been faultless. The choice of putting attendees and lecturers together in a hotel, as in other past GULP schools, fostered frequent and fruitful interactions, minimizing any logistic problem and leaving little room for distractions. The scholastic obligations, though, have been relieved by some social events, and especially by the delightfulness of the location. More information about the 2000 ISCL courses is available at the following URL: ~etalle /school 2000/index.html BNVKI newsletter 140

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16 ROBOTIC RESEARCH IN UTRECHT Walter de Back INTRODUCTION Agent technology and autonomous robotics are active research topics. In both areas there is a quest for control methods providing fast, accurate, robust behaviour. At the Institute for Information and Computing Science (ICS) at the University of Utrecht we have a modest robot laboratory (RoboLab) for this kind of research. Currently, there are two parallel lines of ongoing research. (1) The group Intelligent Systems (IS), interested in cognitive robotics, has developed an agent programming language, 3APL, for the design and construction of intelligent agents like Personal Assistants. (2) A group of students, working in the RoboLab, has developed a toolkit for robotic control, RU-SMART, for the design and implementation of intelligent behaviour for real-world robots. The latter system was used in building a soccer-robot for participating in the European Championships RoboCup 2000 in Amsterdam. This article provides an overview of the activities of the RoboLab at the University of Utrecht. ROBOLAB In 1997, the discipline group IS of the Institute for ICS founded a robot laboratory. The main goals of this RoboLab are: (1) to subject the theoretical efforts of the group (especially with respect to cognitive robotics) to experimental testing and (2) to get students interested and involved in the research on intelligent systems in general and robotics in specific. Cognitive Robotics views programs as intelligent agents acting on our behalf. To support this kind of programming, the group IS has proposed the agent-based programming language 3APL. In the RoboLab, there are ideas to combine 3APL with low-level controllers to study the possibility to move cognitive robotics out of artificial worlds and towards complex real worlds. Since 1998 there is a large involvement of students in the RoboLab through both curricular and extra-curricular activity. Within the second year project-based course, the so-called software project, there have been assignments to write robotic control software. Besides this course, the largest part of the activity in the lab has been extra-curricular, due to the efforts of a group of enthusiastic students interested in robotics. These students have different backgrounds: cognitive artificial intelligence(cki), technical artificial intelligence(tki), and computer science. This group has developed a robotic toolkit, RU-SMART, which was used to participate in RoboCup 2000 in Amsterdam. The RoboLab uses four robots: three Pioneers 1 (P1) and one Pioneer 2 (P2) from ActivMedia[1]. All our robots have two driven wheels and a castor wheel. The P1s have eight sonar sensors in front and a simple camera. They do not have on-board computers, but are controlled by an offboard computer via a modem connection. The P2 has sixteen sonar sensors all around, a pan-tilt-zoom camera, a compass, and a laser range finder. It has a Pentium2 on-board computer for all processing. For communication with an off-board computer or other robots, it is provided with wireless ethernet. 3APL In cognitive robotics, one is concerned with designing robots encompassing highlevel cognitive functions: robots that sense, reason about and act in a constantly changing world. 3APL is a high-level agent programming language, that takes the idea that agents have different mental states (such as beliefs, goals) seriously; the constructs of the language immediately BNVKI newsletter 142

17 address these states. 3APL include features for: representing and querying the agent s beliefs; belief updating for incorporating new and removing existing information in the agent s belief base; and goal updating to facilitate practical reasoning, that is, for planning and the reconsideration of adopted plans [2]. RU-SMART RU-SMART is an acronym for RoboLab Utrecht s Smart Multi-purpose Autonomous Robot Toolkit. The toolkit, which is still in development, supports the design and implementation of robotic control for intelligent behaviour of realworld robots. The requirements set for the system include robot- and applicationindependancy, fast, robust control and easy implementation of behaviour[3]. Its open architecture allows implementation of different control structures. RU-SMART consist of a parallel modules for perception and world modelling, task execution, communication and motor control[4]. The task execution module can be constructed in different ways (while maintaining the rest). Approaches we have explored so far include a simple planning system and a behaviour-based subsumption architecture[5], which we used in the RoboCup application. Currently, we are exploring the possibilities to use evolutionary techniques in our robotic systems, e.g. evolutionary robotics [6]. In the near future, we are going to use a variety of neural networks and genetic algorithms to solve optimisation and action selection problems. ROBOCUP-SOCCER RoboCup [7] is an international project to promote artificial intelligence, robotics, and related fields. It is an attempt to foster AI and intelligent robotics research by providing a standard problem where wide range of technologies can be integrated and examined. RoboCup chose to use the game of soccer as a central topic of research, aiming at innovations to be applied for socially significant problems and industries. The Dutch RoboCup team is a joint project of the University of Amsterdam (UvA), the Technical University of Delft (TUD), and the University of Utrecht. The resulting robot team has participated in the European Championship RoboCup 2000 held in Amsterdam[8]. The UvA and the TUD were responsible for developing a goalkeeper and defenders, for which they used Nomadic Scout robots. The effort of our RoboLab was concentrated on the research and development of the team s attacker. For this task, we used our P2 robot, Dexter, because of its fast acceleration, the on-board computer and the laser range finder. Dexter was equipped with a pneumatic device for ball handling and kicking, which was developed at the TUD. For controlling the robot, we developed a soccer application in RU-SMART. This application is an implementation of a subsumption architecture in the task execution module (using the worldmap, motor control and communication modules provided in RU-SMART). No more than three weeks before the start of the RoboCup event, we had the hardware of Dexter up and running for the first time. At that point, we only had tested RU-SMART (with a simplified soccer application) on the simple P1 robots. Therefore, all Dexter s behaviour had to be made in these couple of weeks. RU-SMART supports the bottom-up implementing of behaviour. The different behaviours can be implemented, tested and debugged separately in an incremental fashion. This feature allowed us to develop all soccer behaviour in this little time. Moreover, our approach to a subsumption based control proved to result in coherent, smooth behaviour. BNVKI newsletter 143

18 During the tournament, the team showed an improving performance. Both Dexter and the goalkeeper and defenders from the UvA and the TUD were getting better due to the great efforts of the members of the Dutch team. Unfortunately this was not enough to get to the top of the tournament. This was due to problems with Dexter s hardware, some software problems within the team and the absence of communication between the robots. Almost half of Dexter s play time was lost because of a broken axis. Even with this setback, our last game, versus Shariff from Iran, who later went on to become the European Champions, was a very exciting one. The Dutch team, also called RobOranje, has reached a disappointing sixth place in this tournament. However, considering this was the first time we participated in such a project, this result is not to be ashamed about and is encouraging to do better next time. FUTURE Currently, we are making new plans for continuing our RoboCup efforts. We are evaluating our system and planning changes in the software to improve Dexter s performance. To ensure continuation of our knowledge and experience, we are motivating new students to get involved in the development process of RU-SMART and the RoboCup application. To facilitate the growth of the group, we will extend the RoboLab. We will have a separate lab for simulation, meetings and system administration and a lab for the real-world robots with enough space to lay out a RoboCup field. Besides the cooperation with the UvA and the TUD, we have contacts with the AiS group (Autonomous intelligent Systems) of the German research institute GMD and with a group of employees of CFT (Centre for Industrial Technology) within the Philips concern. With both groups, there is a promising exchange of knowledge and information that, we hope, will result in better robotic systems for all parties. We are investigating possibilities to develop applications in RU-SMART using evolutionary techniques. Evolutionary robotics offers a variety of methods for adaptive control and optimisation of behaviour. Besides providing optimal use of the robots capabilities and fast, robust control, this is interesting for the sciences of (neuro-)ethology, cognitive psychology, artificial intelligence, and philosophy. Don t hesitate to contact us via walter@droids.nl or wnback@cs.uu.nl RoboLab Team members: Steven Anker Walter de Back Martijn ten Brink Jannes Faber Arne Koopman Marco Wiering Tijn van der Zant Lars Zwanepol References [1] [2] Hindriks K., de Boer F., van der Hoek W., Meyer J.J.-Ch., Agent Programming in 3APL [3] de Back W., SMART: A Toolkit for Robotic Control [4] Faber J., SMART: Manual [5] Brooks R. A., A Robust Layered Control System for a Mobile Robot [6] Nolfi S., Floreano D., Evolutionary Robotics [7] [8] BNVKI newsletter 144

19 Jaap van den Herik IKAT, Universiteit Maastricht F.M. Waas (November 3, 2000) Principles of Probabilistic Query Optimization. Universiteit van Amsterdam. Promotor: Prof.dr. M.L. Kersten. H.P. Ditmarsch (November 20, 2000) Knowledge Games. Rijksuniversiteit Groningen. Promotores: Prof.dr. G.R. Renardel de Lavalette, Prof.dr. J.F.A.K. van Benthem. J. Romein (January 18, 2001) Multigame An Environment for Distributed Game-Tree Search. Vrije Universiteit van Amsterdam. Promotor: Prof.dr.ir. H.E. Bal. R. van der Goot (January 19, 2001) K. Hindriks (February 5, 2001) Agent Programming Languages: Programming with Mental Models. Universiteit Utrecht. Promotor: prof.dr. J.-J.Ch. Meyer, copromotoren: dr. W. v.d. Hoek and dr. F.S. de Boer. Below we provide you with the total number of the Ph.D. theses announced in For comparison we have given the list containing the numbers of the previous years. This list contains the adjusted numbers. 1994: : : : 30 (for reasons see above) 1998: : : As a courtesy to the 2000 newborn doctores I am pleased to honour them (again) by mentioning them below together with their promotion date. J. Kamps (10-3), F. Niesink (28-3), J. Hulstein (7-4), K. Holtman (29-5), C.M.T. Metselaar (20-6), S. Verbaten (22-6), E. de Jong (23-6), R.W. van der Pol (14-9), Z. Zouridis (15-9), V. Coupé (27-9), G. de Haan (10-10), C.E. Areces (12-10), R.M. van Eijk (18-10), N. Peek (30-10), P. Jones (7-11), F. Waas (3-11). E. Smirnov (February 22, 2001) Conjunctive and Disjunctive Version Spaces with Instance-Based Boundary Sets. Universiteit Maastricht. Promotor: Prof.dr. H.J. van den Herik M. van Someren (March 1, 2001) Learning as problem solving. Universiteit van Amsterdam. Promotor: prof.dr. B.J. Wielinga. S. Renooij (March 12, 2001) Qualitative Approaches to Quantifying Probabilistic Networks. Universiteit Utrecht. Promotoren: Prof.dr. J.-J.Ch. Meyer and Prof.dr.ir. L.C. van der Gaag, co-promotor: dr. C.L.M. Witteman. BNVKI newsletter 145

20 THE SKBS PRIZE Jaap van den Herik Universiteit Maastricht The Foundation of Knowledge-Based Systems (SKBS) has significantly supported AI research in The Netherlands in the late 1980s and the 1990s. The Foundation still exists, but employs currently a limited number of activities. A notable point to mention is that, the last Ph.D. student recently has passed the thesis defence with success. Similarly to last year, the SKBS has put up a prize for the best demonstration during the BNAIC session on applications and demonstrations. As announced in the October issue of the BNVKI newsletter, there were ten Start-up Companies which would like to demonstrate their products. For some companies Start-up should be in brackets, but what really was meant was new research leading to new demonstrations. As such, the session was well organized and a report by Luc Dehaspe, the session chair, will reveal some particularities of the demonstrating Companies. A jury consisting of Jaap van den Herik (chair), Cees Witteveen, Bert Kappen, Peter van Lith and Bas Zinsmeister (coordinator), inspected the demonstrations and made a report. During a cursory inspection of the demonstrations it became clear that Bas Zinsmeister (Bolesian) should withdraw from the Jury since one of his stable mates was in the running for the SKBS prize, i.e., Edwin Zopfi with the demo of HKT, which stands for HerKennings Technology. The demonstration had as its domain notarial acts. The idea is to extract from notarial acts all relevant information for taking a decision. Emphasis was on transfer acts and mortgage deeds. A formal grammar was designed to support the bottom-up recognition process. Unfortunately, following this approach too many ambiguities emerged. The system many times could not extract the correct information. Therefore, the bottom-up procedure was combined with a top-down procedure, in which the standard act textual procedure was followed. As we all know, notaries are very diligent persons and even if they deviate from the standard path (and set their own standards) they do so in an easily to recognize fashion. The combination turned out to be a success and the demonstration can leave its pilotproject status soon. Another contestant for the SKBS-prize was Lube Select: A fuzzy-logic decision support system for bearing lubrication selection via Internet.The program was demonstrated by Gerard Schram, from SKF Engineering & Research Centre B.V., Nieuwegein. The main idea is that appropriate (grease) lubrication is crucial in bearing applications. The knowledge incorporated was demonstrated in three groups: (1) understanding on grease lubrication, (2) showing empirical test results, and (3) showing applications experience. An example of the latter group is that the system showed to be aware of the possibility whether the lubrication was food approved. The system made a very sophisticated impression and its performance was alike. The system was to the point, as were its interfaces. The questions and answers were very well distributed over the screen and nowhere the user lost overview. LubeSelect was designed and specified according to SDF (System Development Framework), during the period April 1999 to August Since its implementation 1400 users have received advice from this system that is internally available via Internet. BNVKI newsletter 146