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608
Impediments to Universal PreferenceBased Default Theories
 Artificial Intelligence
, 1989
"... Research on nonmonotonic and default reasoning has identified several important criteria for preferring alternative default inferences. The theories of reasoning based on each of these criteria may uniformly be viewed as theories of rational inference, in which the reasoner selects maximally preferr ..."
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Cited by 65 (11 self)
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Research on nonmonotonic and default reasoning has identified several important criteria for preferring alternative default inferences. The theories of reasoning based on each of these criteria may uniformly be viewed as theories of rational inference, in which the reasoner selects maximally preferred states of belief. Though researchers have noted some cases of apparent conflict between the preferences supported by different theories, it has been hoped that these special theories of reasoning may be combined into a universal logic of nonmonotonic reasoning. We show that the different categories of preferences conflict more than has been realized, and adapt formal results from social choice theory to prove that every universal theory of default reasoning will violate at least one reasonable principle of rational reasoning. Our results can be interpreted as demonstrating that, within the preferential framework, we cannot expect much improvement on the rigid lexicographic priority mechanisms that have been proposed for conflict resolution.
Searching the Workplace Web
, 2003
"... The social impact from the World Wide Web cannot be underestimated, but technologies used to build the Web are also revolutionizing the sharing of business and government information within intranets. In many ways the lessons learned from the Internet carry over directly to intranets, but others do ..."
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Cited by 53 (4 self)
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The social impact from the World Wide Web cannot be underestimated, but technologies used to build the Web are also revolutionizing the sharing of business and government information within intranets. In many ways the lessons learned from the Internet carry over directly to intranets, but others do not apply. In particular, the social forces that guide the development of intranets are quite di#erent, and the determination of a "good answer" for intranet search is quite di#erent than on the Internet. In this paper we study the problem of intranet search. Our approach focuses on the use of rank aggregation, and allows us to examine the e#ects of di#erent heuristics on ranking of search results.
Elections Can be Manipulated Often
"... The GibbardSatterthwaite theorem states that every nontrivial voting method between at least 3 alternatives can be strategically manipulated. We prove a quantitative version of the GibbardSatterthwaite theorem: a random manipulation by a single random voter will succeed with nonnegligible probab ..."
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Cited by 51 (1 self)
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The GibbardSatterthwaite theorem states that every nontrivial voting method between at least 3 alternatives can be strategically manipulated. We prove a quantitative version of the GibbardSatterthwaite theorem: a random manipulation by a single random voter will succeed with nonnegligible probability for every neutral voting method between 3 alternatives that is far from being a dictatorship.
An Axiomatic Approach for Result Diversification
 WWW 2009 MADRID!
, 2009
"... Understanding user intent is key to designing an effective ranking system in a search engine. In the absence of any explicit knowledge of user intent, search engines want to diversify results to improve user satisfaction. In such a setting, the probability ranking principlebased approach of present ..."
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Cited by 51 (1 self)
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Understanding user intent is key to designing an effective ranking system in a search engine. In the absence of any explicit knowledge of user intent, search engines want to diversify results to improve user satisfaction. In such a setting, the probability ranking principlebased approach of presenting the most relevant results on top can be suboptimal, and hence the search engine would like to tradeoff relevance for diversity in the results. In analogy to prior work on ranking and clustering systems, we use the axiomatic approach to characterize and design diversification systems. We develop a set of natural axioms that a diversification system is expected to satisfy, and show that no diversification function can satisfy all the axioms simultaneously. We illustrate the use of the axiomatic framework by providing three example diversification objectives that satisfy different subsets of the axioms. We also uncover a rich link to the facility dispersion problem that results in algorithms for a number of diversification objectives. Finally, we propose an evaluation methodology to characterize the objectives and the underlying axioms. We conduct a large scale evaluation of our objectives based on two data sets: a data set derived from the Wikipedia disambiguation pages and a product database.
Universitylevel computerassisted instruction at Stanford
 Stanford University
, 1981
"... This article provides an overview of current work on universitylevel computerassisted instruction at Stanford University. Brief descriptions are given of the main areas ..."
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Cited by 48 (5 self)
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This article provides an overview of current work on universitylevel computerassisted instruction at Stanford University. Brief descriptions are given of the main areas
Merging with Integrity Constraints
, 1999
"... We consider, in this paper, the problem of knowledge base merging with integrity constraints. We propose a logical characterization of those operators and give a representation theorem in terms of preorders on interpretations. We show the close connection between belief revision and merging oper ..."
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Cited by 45 (10 self)
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We consider, in this paper, the problem of knowledge base merging with integrity constraints. We propose a logical characterization of those operators and give a representation theorem in terms of preorders on interpretations. We show the close connection between belief revision and merging operators and we show that our proposal extends the pure merging case (i.e. without integrity constraints) we study in a previous work. Finally we show that Liberatore and Schaerf commutative revision operators can be seen as a special case of merging.
P.: Aggregating sets of judgments: An impossibility result
 Economics and Philosophy
"... Suppose that the members of a certain group each hold a rational set of judgments on some interconnected questions. And imagine that the group itself now has to form a collective, rational set of judgments on those questions. How should it go about dealing with this task? We argue that the question ..."
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Cited by 44 (6 self)
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Suppose that the members of a certain group each hold a rational set of judgments on some interconnected questions. And imagine that the group itself now has to form a collective, rational set of judgments on those questions. How should it go about dealing with this task? We argue that the question raised is subject to a difficulty that has recently been noticed in discussion of the doctrinal paradox in jurisprudence. And we show that there is a general impossibility theorem that that difficulty illustrates. Our paper describes this impossibility result and provides an exploration of its significance. The result naturally invites comparison with Kenneth Arrow's famous theorem (Arrow, 1963 and 1984; Sen, 1970) and we elaborate that comparison in a companion paper (List and Pettit, 2002). The paper is in four sections. The first section documents the need for various groups to aggregate the sets of judgments held by members on certain issues; the second presents the discursive paradox that arises This paper developed from the joint discussion and exploration of themes raised in Pettit (2001b), but the formal proof of the impossibility result is the work of Christian List. We
A short introduction to computational social choice
 Proc. 33rd Conference on Current Trends in Theory and Practice of Computer Science
, 2007
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On the Difference between Merging Knowledge Bases and Combining them
, 2000
"... We investigate the logical properties of knowledge base combination operators proposed in the literature. These operators are based on the selection of some maximal subsets of the union of the knowledge bases. We argue that they are not fully satisfactory to merge knowledge bases, since the so ..."
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Cited by 43 (12 self)
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We investigate the logical properties of knowledge base combination operators proposed in the literature. These operators are based on the selection of some maximal subsets of the union of the knowledge bases. We argue that they are not fully satisfactory to merge knowledge bases, since the source of information is lost in the combination process. We show that it is the reason why those operators do not satisfy a lot of logical properties. Then we propose to use more rened selection mechanisms in order to take the distribution of information into account in the combination process. That allows to dene merging operators with a more subtle behaviour. 1 INTRODUCTION In the elds of articial intelligence and databases, one is often faced with conicting information coming from several sources. Thus, an important problem in such cases is how to reach a coherent piece of information from these contradictory ones. For example, if one wants to build an expert system from a ...
Integrating Multiplicative Preference Relations in a Multipurpose Decision Making Model Based on Fuzzy Preference Relations
 and Systems
, 1998
"... The aim of this paper is to study the integration of multiplicative preference relation as a preference representation structure in fuzzy multipurpose decision making problems. Assuming fuzzy multipurpose decision making problems under different preference representation structures (ordering, utilit ..."
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Cited by 39 (20 self)
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The aim of this paper is to study the integration of multiplicative preference relation as a preference representation structure in fuzzy multipurpose decision making problems. Assuming fuzzy multipurpose decision making problems under different preference representation structures (ordering, utilities and fuzzy preference relations) and using the fuzzy preference relations as uniform representation element, the multiplicative preference relations are incorporated in the decision problem by means of a transformation function between multiplicative and fuzzy preference relations. A consistency study of this transformation function, which demonstrates that it does not change the informative content of multiplicative preference relation, is shown. As a consequence, a selection process based on fuzzy majority for multipurpose decision making problems under multiplicative preference relations is presented. To design it, an aggregation operator of information, called ordered weighted geometr...