AIList-REQUEST@SRI-AI.ARPA (AIList Moderator Kenneth Laws) (01/23/86)
AIList Digest Thursday, 23 Jan 1986 Volume 4 : Issue 13 Today's Topics: Seminars - Controlling Backward Inference (SRI) & Automata Approach to Program Verification (MIT) & Problem Solving for Distributed Systems (MIT) & Problem-Solving Languages (CSLI) & Pointwise Circumscription (SU) & Methodological Issues in Speech Recognition (Edinburgh) & Intuitionistic Logic Programming (UPenn) ---------------------------------------------------------------------- Date: Wed 15 Jan 86 15:22:41-PST From: LANSKY@SRI-AI.ARPA Subject: Seminar - Controlling Backward Inference (SRI) CONTROLLING BACKWARD INFERENCE Dave Smith (DE2SMITH@SUMEX-AIM) Stanford University 11:00 AM, MONDAY, January 20 SRI International, Building E, Room EJ228 (new conference room) Effective control of inference is a critical problem in Artificial Intelligence. Expert systems have made use of powerful domain-dependent control information to beat the combinatorics of inference. However, it is not always feasible or convenient to provide all of the domain-dependent control that may be needed, especially for systems that must handle a wide variety of inference problems, or must function in a changing environment. In this talk a powerful domain-independent means of controlling inference is proposed. The basic approach is to compute expected cost and probability of success for different backward inference strategies. This information is used to select between inference steps and to compute the best order for processing conjuncts. The necessary expected cost and probability calculations rely on simple information about the contents of the problem solvers database, such as the number of facts of each given form and the domain sizes for the predicates and relations involved. ------------------------------ Date: 01/16/86 17:18:02 From: LISA at MC.LCS.MIT.EDU Subject: Seminar - Automata Approach to Program Verification (MIT) [Forwarded from the MIT bboard by SASW@MC.LCS.MIT.EDU.] DATE: Thursday, January 23, 1986 TIME: 3:45 p.m......Refreshments 4:00 p.m......Lecture PLACE: NE43 - 512A "AN AUTOMATA-THEORETIC APPROACH TO AUTOMATIC PROGRAM VERIFICATION" MOSHE Y. VARDI IBM Almaden Research Center We describe an automata-theoretic approach to automatic verification of concurrent finite-state programs by model checking. The basic idea underlying the approach is that for any temporal formula PHI we can construct an automaton A(PHI) that accepts precisely the computations that satisfy PHI. The model-checking algorithm that results from this approach is much simpler and cleaner than tableaux-based algorithms. We also show how the approach can be extended to probabilistic concurrent finite-state programs. Albert Meyer Host ------------------------------ Date: Thu 16 Jan 86 11:49:34-EST From: John J. Doherty <JOHN@XX.LCS.MIT.EDU> Subject: Seminar - Problem Solving for Distributed Systems (MIT) [Forwarded from the MIT bboard by SASW@MC.LCS.MIT.EDU.] Date: January 24, 1986 Place: NE43-512A Time: Refreshments 2:15 P.M. Seminar 2:30 P.M. Problem Solving for Distributed Systems: An Uplifting Experiment in Progress Herb Krasner Member of the Technical Staff MCC Software Technology Project This presentation describes the empirical studies efforts of the STP Design Process Group focusing on models of the design process. Preliminary findings of the "lift" experiment are reported, from which a model of expert designer behavior and high leverage characteristics is being derived. Goals of the pilot study, experimental setup, problem, data analysis technique, hypotheses and subsequent activities are discussed. The "lift" experiment was initiated to examine the early stages of design problem solving behavior prototypical of users of the futuristic software design environment LEONARDO. It addresses the large effect of individual differences on productivity data, and differs from previous studies in its focus on large-scale design problems. Host: Irene Greif ------------------------------ Date: Wed 15 Jan 86 16:52:56-PST From: Emma Pease <Emma@SU-CSLI.ARPA> Subject: Seminar - Problem-Solving Languages (CSLI) [Excerpted from the CSLI Newsletter by Laws@SRI-AI.] CSLI ACTIVITIES FOR NEXT THURSDAY, January 23, 1986 2:15 p.m. CSLI Seminar Computer Problem Solving Languages, Programming Languages and Mathematics Curtis Abbott (Abbott@xerox) Computer Problem Solving Languages, Programming Languages and Mathematics by the Semantically Rational Computer Languages Group Programming languages are constrained by the requirement that their expressions must be capable of giving rise to behavior in an effective, algorithmically specified way. Mathematical formalisms, and in particular languages of logic, are not so constrained, but their applicability is much broader than the class of problems anyone would think of ``solving'' with computers. This suggests, and I believe, that formal languages can be designed that are connected with the concerns associated with solving problems with computers yet not constrained by effectiveness in the way programming languages are. I believe that such languages, which I call ``computer problem solving languages,'' provide a more appropriate evolutionary path for programming languages than the widely pursued strategy of designing ``very high level'' programming languages, and that they can be integrated with legitimate programming concerns by use of a transformation-oriented methodology. In this presentation, I will give several examples of how this point of view impacts language design, examples which arise in Membrane, a computer problem solving language I am in the process of designing. --Curtis Abbot ------------------------------ Date: 17 Jan 86 1639 PST From: Vladimir Lifschitz <VAL@SU-AI.ARPA> Subject: Seminar - Pointwise Circumscription (SU) Pointwise Circumscription Vladimir Lifschitz Thursday, January 23, 4pm, MJH 252 (I have a few copies of the paper in my office, MJH 362). ABSTRACT Circumscription is logical minimization, that is, the minimization of extensions of predicates subject to restrictions expressed by predicate formulas. When several predicates are to be minimized, circumscription is usually thought of as minimization with respect to an order defined on vectors of predicates, and different ways of defining this order correspond to different kinds of circumscription: parallel and prioritized. The purpose of this paper is to discuss the following principle regarding logical minimization: Things should be minimized one at a time. This means, first of all, that we propose to express the circumscription of several predicates by the conjunction of several minimality conditions, one condition for each predicate. The difference between parallel and prioritized circumscription will correspond to different selections of predicates allowed to vary in each minimization. This means, furthermore, that we propose to modify the definition of circumscription so that it will become an "infinite conjunction" of "local" minimality conditions; each of these conditions expresses the impossibility of changing the value of the predicate from True to False at one point. (Formally, this "infinite conjunction" will be represented by means of a universal quantifier). This is what we call "pointwise circumscription". We argue that this approach to circumscription is conceptually simpler than the traditional ``global'' approach and, at the same time, leads to generalizations with the additional flexibility and expressive power needed in applications to the theory of commonsense reasoning. Its power is illustrated, in particular, on a problem posed by Hanks and McDermott, which apparently cannot be solved using other existing formalizations of non-monotonic reasoning. ------------------------------ Date: Tue, 21 Jan 86 10:44:43 GMT From: Gideon Sahar <gideon%edai.edinburgh.ac.uk@cs.ucl.ac.uk> Subject: Seminar - Methodological Issues in Speech Recognition (Edinburgh) Department of Artificial Intelligence, University of Edinburgh, and Artificial Intelligence Applications Institute Edinburgh Artificial Intelligence Seminars Speaker - Dr. Henry Thompson, Dept. of A.I., University of Edinburgh Title - Methodological issues in Speech Recognition Abstract - What methodological issues arise from the belief that fully automatic high quality unrestricted speech recognition is impossible, when one has overall technical responsibility for a multi-year multi-million pound Alvey Large Scale Demonstrator? I will give a brief overview of the overall structure of the project, and discuss at more length two basic issues: - Why top-down vs. bottom-up is the wrong question, and selectional vs. instructional interaction is the right question, and what the right answer is. - How giving up on fully automatic ... changes the way you do things in surprising ways. ------------------------------ Date: Tue, 21 Jan 86 23:27 EST From: Tim Finin <Tim%upenn.csnet@CSNET-RELAY.ARPA> Subject: Seminar - Intuitionistic Logic Programming (UPenn) From: Dale Miller <Dale@UPenn> UPenn Math-CS Logic Seminar An Intuitionistic Basis for Extending Logic Programming Dale Miller Tuesday 28 Jan 86, 4:30 - 6:00, 4E17 DRL There is a very natural extension to Horn clauses which involves extending the use of implication. This extension has a natural operational semantics which is not sound with respect to classical logic. We shall show that intuitionistic logic, via possible worlds semantics, provides the necessary framework to give a sound and complete justification of this operational semantics. This will be done by providing a least fix-point construct of a Kripke-model. We shall also show how this logic can be used to provide logic programming languages with a logical foundations for each of the following programming features: program modules, recursive call memo-izing, and local environments (permanent vs. temporary asserts). This extension to logic programming can also simulate various features of negation - not through logical incompleteness as in negation-by-failure, but through constructing proofs of a certain kind. ------------------------------ End of AIList Digest ********************