clarke@utcsri.UUCP (Jim Clarke) (01/13/88)
(SF = Sandford Fleming Building, 10 King's College Road) SUMMARY: THEORY/SYSTEMS SEMINAR, Tuesday, January 19, 11 am, SF1105 -- R.D. Tennent: "Towards a Language for Applicative AND Imperative Programming" A.I. SEMINAR, Tuesday, January 19, 2 pm, SF1105 -- Anand S. Rao: "Semantics of Dynamic Epistemic Systems" SYSTEMS SEMINAR, Thursday, January 21, 11 am, SF1101 -- James R. Cordy: "TuringTool: A Knowledge-Based User Interface to Aid in the Software Maintenance Task" -------- THEORY/SYSTEMS SEMINAR, Tuesday, January 19, 11 am, SF1105 ** Professor R.D. Tennent Queen's University "Towards a Language for Applicative AND Imperative Programming" Both the applicative and the imperative programming paradigms have signifi- cant advantages. Is it possible for a language to support both of these paradigms adequately, while also retaining the advantages of each of the "pure" frameworks? Ideally, such a programming language would allow simple reasoning about properties of both imperative and applicative aspects of programs but also have simple and efficient implementations, and would pro- vide the security and efficiency of statically-typed languages, but also have the flexibility and syntactic succinctness of type-less languages. No programming language in current use achieves these ambitious goals, but over the last ten years there have been several important developments, and this talk will attempt to justify my belief that these goals will soon be achievable. A.I. SEMINAR, Tuesday, January 19, 2 pm, SF1105 Dr. Anand S. Rao IBM T.J. Watson Research Center (On leave from U. of Sydney, Australia) "Semantics of Dynamic Epistemic Systems" In classical first-order logic the addition of a new axiom to a set of axioms can never decrease the set of theorems. This property is often called the Monotonicity property. Logics which lack this property are called Nonmonotonic logics and have received a great deal of attention in the AI community. Three of the most important such nonmonotonic logics are Default Logic, Circumscription and Autoepistemic logic. All these logics make some assumptions about the current world and `jump to con- clusions' based on incomplete information. An important aspect of nonmonotonicity, not addressed by the above logics, is the dynamic process of Knowledge (or Belief) Revision. It is the pro- cess by which an agent revises his existing knowledge in the light of new(possibly contradictory) information from the external world. We pro- vide a meta-theoretic, modal and axiomatic theory of the dynamic aspects of such systems and show their equivalence. The axioms which we provide for dynamic epistemic systems helps us to derive new knowledge based on the old knowledge and the new information. Our work has far reaching applications in the areas of Planning, Database Updates and Speech Act Theory. We conclude the talk by taking a simple example from the blocks-world and showing how our approach avoids the Frame Problem and the Ramification Problem. The main contribution of this work is in providing a model theory and proof theory of dynamic systems. (This is a joint work with Norman Foo) SYSTEMS SEMINAR, Thursday, January 21, 11 am, SF1101 ** Prof. James R. Cordy Queen's University at Kingston "TuringTool: A Knowledge-Based User Interface to Aid in the Software Maintenance Task" TuringTool is a programming environment specifically designed to support the maintenance task. In order to avoid the cognitive overhead of simul- taneously interpreting several different representations of the program as a unit, TuringTool bases all of its views of the program on a single comprehensive viewing paradigm: source text elision. This talk describes how this paradigm can be used to represent several kinds of views appropri- ate to the maintenance of large source programs, including structural views and views based on knowledge of the maintenance task. The technique easily extends to allow representation of complex programmer knowledge using sim- ple set theoretic operators to combine the knowledge encoded in several views into one. Key words : Programming environments, software maintenance, user interfaces, knowledge-based systems, elision, programming languages, Turing. ** These two sections are part of our QUEEN'S WEEK. Professor S. Akl also from Queens will be speaking at one of seminars later this term. -- Jim Clarke -- Dept. of Computer Science, Univ. of Toronto, Canada M5S 1A4 (416) 978-4058 BITNET,CSNET: clarke@csri.toronto.edu CDNNET: clarke@csri.toronto.cdn UUCP: {allegra,cornell,decvax,linus,utzoo}!utcsri!clarke