Browsing by Subject "Knowledge Representation"
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Item Open Access Classification by feature partitioning(Springer/, 1996) Guvenir, H. A.; Şirin, İ.This paper presents a new form of exemplar-based learning, based on a representation scheme called jfaliirf parluinning, and a panitular implementation of this technique called CFF (for Classification by feature Partioning). Learning in CFP is accomplished by storing the objects separately in each (tenure dimension as disjoint sets of values called segments A segment is; expanded through generalization or specialized by dividing in into sub-segments. Cklassification is based on a weighted voting among the individual productions of the features, which are simply the class values of the segments corresponding to the values of a test instance fur each feature An empirical evaluation of CFP and its comparison with two other classification techniques, lhai consider each feature separately are given. © 1996 Kluwer Academic Publishers,.Item Open Access Contexts and situations(Bilkent University, 1994) Surav, MehmetThe issue of context arises in assorted areas of Artificial Intelligence, Mathematical Logic, and Natural Language Semantics. Although its importance is realized by various researchers, there is not much work towards a useful formalization. In this thesis, we will try to identify the problem, and decide what we need for an acceptable (formal) account of the notion of context. We will present a preliminary model (based on Situation Theory) and give examples to show the use of context in various fields, and the advantages gained by the acceptance of our proposal.Item Open Access Maximizing benefit of classifications using feature intervals(Springer, Berlin, Heidelberg, 2003) İkizler, Nazlı; Güvenir, H. AltayThere is a great need for classification methods that can properly handle asymmetric cost and benefit constraints of classifications. In this study, we aim to emphasize the importance of classification benefits by means of a new classification algorithm, Benefit-Maximizing classifier with Feature Intervals (BMFI) that uses feature projection based knowledge representation. Empirical results show that BMFI has promising performance compared to recent cost-sensitive algorithms in terms of the benefit gained.Item Open Access Nonstandard set theories and information management(Springer/, 1996) Akman, V.; Pakkan, M.The merits of set theory as a foundational tool in mathematics stimulate its use in various areas of artificial intelligence, in particular intelligent information systems. In this paper, a study of various nonstandard treatments of set theory from this perspective is offered. Applications of these alternative set theories to information or knowledge management are surveyed.Item Open Access Representing the Zoo World and the Traffic World in the language of the Causal Calculator(Elsevier, 2004-03) Akman, V.; Erdoğan, S. T.; Lee, J.; Lifschitz, V.; Turner, H.The work described in this report is motivated by the desire to test the expressive possibilities of action language C+. The Causal Calculator (CCALC) is a system that answers queries about action domains described in a fragment of that language. The Zoo World and the Traffic World have been proposed by Erik Sandewall in his Logic Modelling Workshop—an environment for communicating axiomatizations of action domains of nontrivial size. The Zoo World consists of several cages and the exterior, gates between them, and animals of several species, including humans. Actions in this domain include moving within and between cages, opening and closing gates, and mounting and riding animals. The Traffic World includes vehicles moving continuously between road crossings subject to a number of restrictions, such as speed limits and keeping a fixed safety distance away from other vehicles on the road. We show how to represent the two domains in the input language of CCALC, and how to use CCALC to test these representations.(C)2003 Elsevier B.V. All rights reserved.Item Open Access A rule-based video database system architecture(Elsevier, 2002) Dönderler, M. E.; Ulusoy, Özgür; Güdükbay, UğurWe propose a novel architecture for a video database system incorporating both spatio-temporal and semantic (keyword, event/activity and category-based) query facilities. The originality of our approach stems from the fact that we intend to provide full support for spatio-temporal, relative object-motion and similarity-based object-trajectory queries by a rule-based system utilizing a knowledge-base while using an object-relational database to answer semantic-based queries. Our method of extracting and modeling spatio-temporal relations is also a unique one such that we segment video clips into shots using spatial relationships between objects in video frames rather than applying a traditional scene detection algorithm. The technique we use is simple, yet novel and powerful in terms of effectiveness and user query satisfaction: video clips are segmented into shots whenever the current set of relations between objects changes and the video frames, where these changes occur, are chosen as keyframes. The directional, topological and third-dimension relations used for shots are those of the keyframes selected to represent the shots and this information is kept, along with frame numbers of the keyframes, in a knowledge-base as Prolog facts. The system has a comprehensive set of inference rules to reduce the number of facts stored in the knowledge-base because a considerable number of facts, which otherwise would have to be stored explicitly, can be derived by rules with some extra effort. © 2002 Elsevier Science Inc. All rights reserved.Item Open Access Situated modeling of epistemic puzzles(Bilkent University, 1994) Ersan, MuratSituation theory is a mathematical theory of meaning introduced by Jon Barwise and John Perry. It has evoked great theoretical and practical interest and motivated the framework of a few ‘computational’ systems. PROSIT is the pioneering work in this direction. Unfortunately, there is a lack of reallife applications on these systems and this study is a preliminary attempt to remedy this deficiency. Here, we examine how much PROSIT reflects situationtheoretic concepts and solve a group of epistemic puzzles, using the constructs provided by this programming language.Item Open Access Towards situation-oriented programming languages(ACM, 1995) Tin, E.; Akman, V.; Ersan, M.Recently, there have been some attempts towards developing programming languages based on situation theory. These languages employ situation-theoretic constructs with varying degrees of divergence from the ontology of the theory. In this paper, we review three of these programming languages.Item Open Access The use of situation theory in context modeling(Wiley-Blackwell Publishing, Inc., 1997) Akman, V.; Surav, M.At the heart of natural language processing is the understanding of context dependent meanings This paper presents a preliminary model of formal contexts based on situation theory. It also gives a worked-out example to show the use of contexts in lifting, i.e., how propositions holding in a particular context transform when they are moved to another context. This is useful in NLP applications where preserving meaning is a desideratum.