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Artificial Intelligence: A Computational Perspective
 Essentials in Knowledge Representation
, 1994
"... Although the computational perspective on cognitive tasks has always played a major role in Artificial Intelligence, the interest in the precise determination of the computational costs that are required for solving typical AI problems has grown only recently. In this paper, we will describe what in ..."
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Cited by 31 (1 self)
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Although the computational perspective on cognitive tasks has always played a major role in Artificial Intelligence, the interest in the precise determination of the computational costs that are required for solving typical AI problems has grown only recently. In this paper, we will describe what insights a computational complexity analysis can provide and what methods are available to deal with the complexity problem. This work was partially supported by the European Commission as part of DRUMSII, the ESPRIT Basic Research Project P6156. 1 Introduction It is wellknown that typical AI problems, such as natural language understanding, scene interpretation, planning, configuration, or diagnosis are computationally difficult. Hence, it seems to be worthless to analyze the computational complexity of these problems. In fact, some people believe that all AI problems are NPhard or even undecidable. Conceiving AI as a scientific field that has as its goal the analysis and synthesis of...
Computational Models for Integrating Linguistic and Visual Information: A Survey
 Artificial Intelligence Review
, 1995
"... This paper surveys research in developing computational models for integrating linguistic and visual information. It begins with a discussion of systems which have been actually implemented and continues with computationally motivated theories of human cognition. Since existing research spans severa ..."
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Cited by 29 (0 self)
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This paper surveys research in developing computational models for integrating linguistic and visual information. It begins with a discussion of systems which have been actually implemented and continues with computationally motivated theories of human cognition. Since existing research spans several disciplines (e.g., natural language understanding, computer vision, knowledge representation), as well as several application areas, an important contribution of this paper is to categorize existing research based on inputs and objectives. Finally, some key issues related to integrating information from two such diverse sources are outlined and related to existing research. Throughout, the key issue addressed is the correspondence problem, namely how to associate visual events with words and vice versa. 1 Introduction Much has been said about the necessity of linking language and vision in order for a system to exhibit intelligent behaviour [Win73, Wal81]. A complete naturallanguage und...
A Superior Evolutionary Algorithm for 3SAT
 Proceedings of the 7th Annual Conference on Evolutionary Programming, number 1477 in LNCS
, 1998
"... . We investigate three approaches to Boolean satisfiability problems. We study and compare the best heuristic algorithm WGSAT and two evolutionary algorithms, an evolution strategy and an evolutionary algorithm adapting its own fitness function while running. The results show that the adaptive EA ou ..."
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Cited by 23 (0 self)
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. We investigate three approaches to Boolean satisfiability problems. We study and compare the best heuristic algorithm WGSAT and two evolutionary algorithms, an evolution strategy and an evolutionary algorithm adapting its own fitness function while running. The results show that the adaptive EA outperforms the other two approaches. The power of this EA originates from the adaptive mechanism, which is completely problem independent and generally applicable to any constraint satisfaction problem. This suggests that the adaptive EA is not only a good solver for satisfiability problems, but for constraint satisfaction problems in general. 1 Introduction Handling NPcomplete problems with evolutionary algorithms (EAs) is a great challenge. In particular, the presence of constraints makes finding solutions difficult for an EA. In this paper, we investigate solving constraint satisfaction problems (CSPs), in particular the 3SAT problem, and try three different approaches for solving it: O...
What Happened When Database Researchers Met Usability
, 2000
"... This paper is about database researchers building interactive information systems. It tells the reader of their initial enthusiasm and userinduced frustration, the consequent discovery of both humancomputer interaction (hci) world and the concept of system "usability", and finally their ..."
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Cited by 19 (2 self)
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This paper is about database researchers building interactive information systems. It tells the reader of their initial enthusiasm and userinduced frustration, the consequent discovery of both humancomputer interaction (hci) world and the concept of system "usability", and finally their quite successful coupling of hci and databases. Key words: User Interface, Information System, Usability 1. INTRODUCTION It is now generally accepted that factors which mainly influence the success of computerized projects are human and organizational, rather than technological. The mere fact of using computer technologies, even if they are reliable, powerful and innovative, cannot solve work organization problems if the acquired instruments are not in harmony with the attitudes, motivations and competencies of workers in that organization, and also with the social and environmental context of their activities.
Applying GSAT to NonClausal Formulas
 JOURNAL OF ARTIFICIAL INTELLIGENCE RESEARCH
, 1994
"... In this paper we describe how to modify GSAT so that it can be applied to nonclausal formulas. The idea is to use a function which computes the number of clauses of the CNF conversion of a formula which are false under a certain truth assignment, without constructing the conversion itself. The prop ..."
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Cited by 19 (3 self)
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In this paper we describe how to modify GSAT so that it can be applied to nonclausal formulas. The idea is to use a function which computes the number of clauses of the CNF conversion of a formula which are false under a certain truth assignment, without constructing the conversion itself. The proposed methodology applies to most variants of GSAT.
Ontologybased reasoning techniques for multimedia interpretation and retrieval
, 2007
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Regularitybased Perceptual Grouping
 COMPUTATIONAL INTELLIGENCE, 13(4), 582623
"... This paper investigates perceptual grouping from a logical point of view, defining a grouping interpretation as a particular kind of logical expression, and then developing an explicit inference theory in terms of such expressions. First, a regularitybased interpretation language is presented, in w ..."
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Cited by 17 (8 self)
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This paper investigates perceptual grouping from a logical point of view, defining a grouping interpretation as a particular kind of logical expression, and then developing an explicit inference theory in terms of such expressions. First, a regularitybased interpretation language is presented, in which an observed configuration is characterized in terms of the regularities (special configurational classes, e.g. nonaccidental properties) it obeys. The most preferred interpretation in such a system is shown to be the mostregular (maximum “codimension”) model the observed configuration obeys, which is also the unique model in which it is generic (typical). Inference then reduces to a straightforward exercise in Logic Programming. Because generic model assignment involves negation, this reduction requires that a version of the Closed World Assumption (CWA) be adopted. Next, this entire regularitybased machinery is generalized to the grouping problem: here an interpretation is a hierarchical (recursive) version of a model called a parse tree. Foragiven number of dots and a fixed choice of regularity set, it is possible to explicitly enumerate the complete set of possible grouping interpretations, partially ordered by their degree of regularity (codimension). The most preferred interpretation is the one with maximum codimension (i.e.,
The search for Satisfaction
, 1999
"... In recent years, there has been an explosion of research in AI into propositional satis ability (or Sat). There are many factors behind the increased interest in this area. One factor is the improvement in search procedures for Sat. New local search procedures like Gsat are able to solve Sat problem ..."
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Cited by 14 (1 self)
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In recent years, there has been an explosion of research in AI into propositional satis ability (or Sat). There are many factors behind the increased interest in this area. One factor is the improvement in search procedures for Sat. New local search procedures like Gsat are able to solve Sat problems with thousands of variables. At the same time, implementations of complete search algorithms like DavisPutnam have been able to solve open mathematical problems. Another factor is the identi cation of hard Sat problems at a phase transition in solubility. A third factor is the demonstration that we can often solve real world problems by encoding them into Sat. There has also seen an improved theoretical understanding of Sat, particularly in the analysis of such phase transition behaviour. This paper reviews the state of the art for research into satis ability, and discuss applications in which algorithms for satis ability have proved successful.
The Enigma of SAT Hillclimbing Procedures
 Department of AI, University of Edinburgh
, 1992
"... In this paper, we investigate a family of hillclimbing procedures related to GSAT, a greedy random hillclimbing procedure for satisfiability. These procedures are able to solve large and difficult satisfiability problems beyond the range of conventional procedures like DavisPutnam. We explore ..."
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Cited by 13 (4 self)
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In this paper, we investigate a family of hillclimbing procedures related to GSAT, a greedy random hillclimbing procedure for satisfiability. These procedures are able to solve large and difficult satisfiability problems beyond the range of conventional procedures like DavisPutnam. We explore the role of greediness, randomness and hillclimbing in the effectiveness of these procedures. We show that neither greediness nor randomness is crucial to GSAT's performance, and that hillclimbing's importance is limited to a short initial phase of search. In addition, we observe some remarkable and possibly universal features of their search for a satisfying truth assignment. 1 Introduction Many problems in AI are NPhard and are thus, in general, intractable. A solution to this intractability is to give up completeness; that is, instead of an algorithm which is guaranteed to return an answer, we provide a tractable procedure which will often return an answer but may sometimes term...