1998 - 1999 CS Annual Report                                                                  Faculty
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Joseph Y. Halpern

Professor
Co-director: Cognitive Studies Program
halpern@cs.cornell.edu
http://www.cs.cornell.edu/home/halpern

PhD Harvard, 1981

My research is concerned with representing and reasoning about knowledge and uncertainty in multi-agent systems. The work uses tools from logic (particularly modal logic and the idea of possible-worlds semantics), probability theory, distributed systems, game theory, and AI, and I like to think that it contributes to our understanding of each of these areas as well. 

Some themes of my current research include: (1) applying ideas of decision theory to constructing algorithms in asynchronous distributed systems, database systems, and wireless systems, (2) providing foundations for useful qualitative notions of decision theory, (3) reasoning about security. 

University Activities 

  • Co-director: Cognitive Studies Program 

Professional Activities 
  • Fellow, American Association of Artificial Intelligence  
  • Editor-in-chief: Journal of the ACM (as of May, 1997)  
  • Consulting Editor: Chicago Journal of Computer Science 
  • On editorial board: Artificial Intelligence Journal, Information and Computation, Journal of
    Logic and Computation  
  • Member: ACM Publications Board
  • Chairman: ACM Preprint 
  • Repository Project 
    Coordinator: CoRR (Computing Research Repository) 
  • Member: LICS (IEEE Conference on Logic in Computer Science) Advisory Board 
  • President of Board of Directors: Corporation for Theoretical Aspects of Reasoning About
    Knowledge  
  • Program Committee Member, Fifteenth Annual Conference on Uncertainty in Artificial Intelligence (1999) 
  • Member: External Review Committee, Brown Univ., Computer Science Dept. 
Lectures 
  • Using multi-agent systems to represent uncertainty. Invited lecture. Agent's World, Paris,
    France (July 1998).  
  • . Invited tutorial, Fourteenth Annual Conference on Uncertainty in AI, WI, July 1998. 
  • A decision-theoretic approach to the design, analysis, and specification of systems. Invited
    lecture. PARCON98 (Symposium on New Directions in Parallel and Concurrent Computing), New York, Nov 1998.  
  • Reasoning about knowledge. Invited lecture. Australasian Computer Science Conference,
    Auckland, New Zealand, Jan. 1999. 
  • . Invited lecture. American Association for Advancement of Science (AAAS) Conference,
    Los Angeles, Jan. 1999.  
  • Plausibility measures and default reasoning. Distinguished lecture series, Univ. of Toronto, Oct 1998. 
  • . Invited lecture. Workshop  on Logic-Based AI, Washington, D.C., June 1999. 
  • Probability update: conditioning vs. cross-entropy. Columbia Univ., Oct 1998. 
  • Characterizing the common prior assumption, Seventh Conference on Theoretical
    Aspects of Rationality and Knowledge, Evanston, IL, July 1998. 
  • Hypothetical knowledge and counterfactual reasoning. Seventh Conference on Theoretical Aspects of Rationality and Knowledge, Evanston, IL, July 1998.  
  • Axiomatizing causal reasoning. Fourteenth Conference on Uncertainty in AI, Madison, WI, July 1998.  
  • Updating sets of probabilities. Fourteenth Conference on Uncertainty in AI, Madison, WI, July 1998. 
Publications 
  • Performing work efficiently in the presence of faults. SIAM Journal on Computing 27, 5
    (1998), 1457-1491 (with C.Dwork and O. Waarts). 
  • A counterexample to theorems of Cox and Fine. Journal of AI Research 10 (1999), 67-85. 
  • Modeling belief in dynamic systems, Part II: Revision and Update. Journal of AI Research 10 (1999), 117-167 (with N. Friedman).  
  • Common knowledge revisited. Annals of Pure and Applied Logic 96 (1999), 89-105 (with R. Fagin, Y. Moses, and M. Y. Vardi).  
  • Belief revision with unreliable observations. Proceedings of the Fifteenth National Conference on Artificial Intelligence (AAAI98) (1998), 127-134 (with C. Boutilier and N. Friedman).  
  • Axiomatizing causal reasoning. Proceedings of the Fourteenth Conference on Uncertainty in AI (1998), 202-210.  
  • Updating sets of probabilities. Proceedings of the Fourteenth Conference on Uncertainty in AI (1998), 173-182 (with A. Grove).  
  • Hypothetical knowledge and counterfactual reasoning. Proceedings of the Seventh Conference on Theoretical  Aspects of Rationality and Knowledge (1998), 83-96.  
  • Characterizing the common prior assumption. Proceedings of the Seventh Conference on Theoretical Aspects of Rationality and Knowledge (1998), 133-146.  
  • Using counterfactuals in knowledge-based programming. Proceedings of the Seventh
    Conference on Theoretical Aspects of Rationality and Knowledge
    (1998), 97-110 (with Y. Moses).  
  • Sensor-assisted ALOHA for wireless networks. Proceedings of the 1998 International Symposium on Information Theory, (1998), 161 (with T. Fine, S.B. Wicker, and T. Berger). 
  • A decision-theoretic approach to reliable message delivery. Proceedings of the 12th International Symposium on Distributed Computing, Springer-Verlag (1998), 89-103 (with F. Chu).  
  • A knowledge-theoretic analysis of uniform distributed  coordination and failure detectors. Proceedings of the Eighteenth Annual ACM Symposium on Principles of Distributed Computing (1999), 73-82 (with A. Ricciardi). 
  • Least expected cost query optimization: an exercise in utility. Proceedings of the 18th ACM Symposium on Principles of Database Systems (May 1999) (with F. Chu and P. Seshadri). 
    Editorial: Time to publication: a progress report. Journal of the ACM 45, 3 (1998), 379-380
  • A computing research repository. D-Lib Magazine (Nov 1998) (see http://www.dlib.org/dlib/november98/11halpern.html ).  
Patents 
  • Fault-Tolerant Load Management System and Method, Patent Number 5,727,210, 1998 (with C. Dwork and H. R. Strong).