October, 17 October 1997, Port Jefferson (USA)

Evelina Lamma

On October 17, Anthony Bonner, Burkhard Freitag, Laura Giordano and Robert Kowalski organised the post-ILPS97 workshop Dynamics97 on "(Trans) Actions and Change in Logic Programming and Deductive Databases". The intended focus of the workshop was on the dynamic behaviour and the evolution of databases and programs with time. A previous workshop on the same arguments was held as Dagstuhl seminar on "Logic Databases and the Meaning of Change" in 1996. Dynamics97 got some financial support from the ILPS97 organizers, and was very well coordinated by Burkhard Freitag.

The workshop attracted twenty-two participants. Eleven papers were presented on topics concerning the treatment of dynamic behaviour of agent- and knowledge-based systems, the dynamic of databases and logic programs and the reasoning about it, knowledge revision and assimilation.

First session was about agents and knowledge based systems. Joeri Engelfriet compared various approaches for the specification of the dynamics of knowledge-based systems, such as conceptual languages, transaction and dynamic logic and evolving algebras. Jorge Lobo presented a system for workflow management where workflow is treated as a collection of cooperative agents. Reasoning upon workflows is obtained by exploiting languages for reasoning about actions and the workflow control is specified and verified through reactive rules. Focus of the following talk, which I gave, considered distributed logic agents which possibly interact through abduction. Abductive reasoning is supported by a basic coordination protocol which extends a sequential abductive proof procedure to the distributed case.

Second session concerned more theoretical work. Eugenia Ternovskaia presented analogies between the situation calculus, a many-sorted language for specifying change, and inductive definitions. She also discussed the verification of the high-level robot programming language GOLOG, a language based on the situation calculus, when properties of GOLOG programs are inductively defined. Sven-Erik Bornscheuer presented a model for the integration of intelligent reflective and reactive reasoning based on massively parallel nonmonotonic model generation by considering interpretations as agents' current beliefs and perceptions, and applying an immediate consequence operator to obtain direct consequences of these beliefs.

Following session was devoted to databases and their dynamics. Anthony Bonner presented a logical language, called Transaction Datalog, capable of combining standard transactions into complex processes and useful in applications such as CAD, office automation, and workflow management. Burkhard Freitag presented a work for supporting seriazability of logical transactions through the notion of deferred updates. Basically, updates are not immediately executed, but they are deferred and trace of their operations on the database is kept to determine compatibility and incompatibility among them. Maurizio Martelli applied a higher-order language based on linear logic to the specification of Chimera, a deductive object-oriented database system.

Last session was devoted to knowledge revision and assimilation. Stephane Janot presented and compared three change operators, based on forward chaining, for according old knowledge to new evidence in the framework of propositional knowledge. Gerard Wetzel, instead, suggested to use integrity constraints in order to delete logically redundant information which possibly slow down the computation. The framework considered is a general one which integrates abductive and constraint logic programming and semantic query optimisation. Last work presented by Hendrick Decker integrates two procedure supporting respectively schema updates (i.e., intensional database update) and user updates (i.e., view or extensional database updates) in a new abductive procedure for knowledge assimilation.

During the workshop, several discussions and exchange of ideas took place motivating the organisers to plan a new edition to be held during the next Joint Conference and Symposium on Logic Programming in 1998.

Selected papers from both Dynamics97 and the Dagstuhl seminar are going to be published in the Springer LNAI subseries of LNCS. Additional information (and the informal workshop proceedings) can be found at the web site: http://www.uni-passau.de/~freitag/dynamics_97/

Evelina Lamma

DEIS - University of Bologna

Viale Risorgimento, 2

40136 Bologna Italy

Tel. +39 51 6443033

Fax. +39 51 6443073

Email: elamma@deis.unibo.it

http://www-lia.deis.unibo.it/Staff/EvelinaLamma/