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Page 1. Ronald Fagin, Moni Naor, and Peter Winkler Comparing Information Without Leaking It How can two people determine without revealing anything in case they do not? There are surprisingly simple solutions. else to each ...
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1. Introduction It has recently been argued ([HM1]) that the right way to understand and reason about distributed protocols is in terms of how they affect the state of knowledge of the system. The driving force behind the change in... more
1. Introduction It has recently been argued ([HM1]) that the right way to understand and reason about distributed protocols is in terms of how they affect the state of knowledge of the system. The driving force behind the change in knowledge state in a system is ...
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Belief functions are mathematical objects defined to satisfy three axioms that look somewhat similar to the axioms defining probability functions. We argue that there are (at least) two useful and quite different ways of understanding... more
Belief functions are mathematical objects defined to satisfy three axioms that look somewhat similar to the axioms defining probability functions. We argue that there are (at least) two useful and quite different ways of understanding belief functions. The first is as a gen- eralized probability function (which technically corre- sponds to the lower envelope or i&mum of a family of
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Two of the competing approaches to the logical design of relational databases are the third normal form decomposition approach of Codd and the synthetic approach of Bernstein and others. The synthetic approach seems on the surface to be... more
Two of the competing approaches to the logical design of relational databases are the third normal form decomposition approach of Codd and the synthetic approach of Bernstein and others. The synthetic approach seems on the surface to be the more powerful; unfortunately, to avoid ...
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Let D be a database of N objects where each object has m fields. The objects are given in m sorted lists (where the ith list is sorted according to the ith field). Our goal is to find the top k objects according to a monotone aggregation... more
Let D be a database of N objects where each object has m fields. The objects are given in m sorted lists (where the ith list is sorted according to the ith field). Our goal is to find the top k objects according to a monotone aggregation function t, while minimizing access to the lists. The problem arises in several contexts. In particular Fagin (JCSS 1999) considered it for the purpose of aggregating information in a multimedia database system. We are interested in instance optimality, i.e. that our algorithm will be as good as any other (correct) algorithm on any instance. We provide and analyze several instance optimal algorithms for the task, with various access costs and models.
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Two of the competing approaches to the logical design of relational databases are the third normal form decomposition approach of Codd and the synthetic approach of Bernstein and others. The synthetic approach seems on the surface to be... more
Two of the competing approaches to the logical design of relational databases are the third normal form decomposition approach of Codd and the synthetic approach of Bernstein and others. The synthetic approach seems on the surface to be the more powerful; unfortunately, to avoid ...
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I wrote my Ph.D. thesis under Bob Vaught in finite model theory. Interestingly enough, Bob had done very little research himself in finite model theory. However, I'll never forget how on several occasions, he said to me "You seem to be having so much fun doing finite model theory, I wish I were w...more
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Several new logics for belief and knowl edge are introduced and studied, all of which have the property that agents are not logically omniscient. In particular, in these logics, the set of beliefs of an agent does not necessarily contain... more
Several new logics for belief and knowl edge are introduced and studied, all of which have the property that agents are not logically omniscient. In particular, in these logics, the set of beliefs of an agent does not necessarily contain all valid for mulas. Thus, these logics are more suitable than traditional logics for modelling beliefs of humans (or machines)
ABSTRACT
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We consider a class of problems in which an algorithm seeks to compute a function f over a set of n inputs, where each input has an associated price. The algorithm queries inputs sequentially, trying to learn the value of the function for... more
We consider a class of problems in which an algorithm seeks to compute a function f over a set of n inputs, where each input has an associated price. The algorithm queries inputs sequentially, trying to learn the value of the function for the minimum cost. We apply the competitive analysis of algorithms to this framework, designing algorithms that incur
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Abstract There are essential differences between multimedia databases (which may contain complicated objects, such as images), and traditional databases. These differences lead to interesting new issues, and in particular cause us to... more
Abstract There are essential differences between multimedia databases (which may contain complicated objects, such as images), and traditional databases. These differences lead to interesting new issues, and in particular cause us to consider new typos of queries. Wr ...
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In the last year or so, a number of generalizations of these dependencies have appeared: Nicolas's mutual dependencies [Ni], which say that a relation is the join of three of its projections;... more
In the last year or so, a number of generalizations of these dependencies have appeared: Nicolas's mutual dependencies [Ni], which say that a relation is the join of three of its projections; Rissanen's and Aho, Beeri, and Ullman's join dependencies ([Ri], [ABU]), which generalize further to an arbitrary number of projections; Paradaens' transitive dependencies [Pa], which generalize both FDs and
We discuss the relationship between normal forms in a relational database and an allowed set of relational operators. We define "projection-join normal form" (PJ/NF), which is the ultimate normal form when only... more
We discuss the relationship between normal forms in a relational database and an allowed set of relational operators. We define "projection-join normal form" (PJ/NF), which is the ultimate normal form when only projection and join are allowed. Aho, Beeri and Ullman made the counterintuitive discovery that there is a relation schema with a valid decomposition into three of its projections without the decomposition being equivalent to a cascade of decompositions, each into two projections. Because of this possibility, there exist bizarre relation schemata that are in fourth normal form but not in PJ/NF. We also discuss issues associated with allowing the union operator.
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ABSTRACT We discuss the art of applying theory to practice. In particular, we discuss in detail our interactions with two research projects at IBM Almaden: the Garlic project, which built a multimedia database system on top of various... more
ABSTRACT We discuss the art of applying theory to practice. In particular, we discuss in detail our interactions with two research projects at IBM Almaden: the Garlic project, which built a multimedia database system on top of various existing systems, and the Clio project, which developed tools for converting data from one format to another. We discuss the problems we resolved, and the impact this had both on the Garlic or Clio systems and on the broader scientific community. We draw morals from these interactions, including why theoreticians do better theory by working with system builders, and why system builders build better systems by working with theoreticians. We present the remarkably simple Threshold Algorithm, which is optimal in an extremely strong sense: optimal not just in the worst case, or in the average case, but in every case! The Threshold Algorithm and its variants have applications to numerous areas, including information retrieval, fuzzy and uncertain databases, group recommendation systems, and the semantic web .
... We begin the algorithm by writing the edges, one underneath the other: ABC CDE A EF A C E (For convenience, we have put common vertices in the same column.) Page 6. ... The algorithm begins with ABC CDE A EF After deleting the... more
... We begin the algorithm by writing the edges, one underneath the other: ABC CDE A EF A C E (For convenience, we have put common vertices in the same column.) Page 6. ... The algorithm begins with ABC CDE A EF After deleting the isolated nodes B, D, and F, we are left with: ...
It has been argued that knowledge is a useful tool for designing and analyzing complex systems in AI. The notion of knowledge that seems most relevant in this context is an external, information-based notion that can be shown to satisfy... more
It has been argued that knowledge is a useful tool for designing and analyzing complex systems in AI. The notion of knowledge that seems most relevant in this context is an external, information-based notion that can be shown to satisfy all the axioms of the modal logic S5. We carefully examine the properties of this notion of knowledge, and show
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The articles of this volume will be reviewed individually.
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Google, Inc. (search). ...