An up-to-date (for year 2005) presentation of our research in this area as well as related research can be found at the CAISOR website .
We have retained the contents of the present page without change except for this addition to its introduction.
The present page describes work up to mid-1995, and when the present tense is used in the following text it refers to that time. For additional work after that date, please refer to the home pages of Erik Sandewall and of the Knowledge Processing Laboratory.
The following resident researchers participate in this work:
The major aspects of the approach have been summarized in the following journal article. Erik Sandewall: The Range of Applicability of Some Non-monotonic Logics for Strict Inertia. Journal of Logic and Computation, Vol. 4, No. 5, pp. 581-615, 1994. [Click here for abstract only].
An survey of the general topic of nonmonotonic logicist methods for reasoning about actions and change has been written by Erik Sandewall and Yoav Shoham as a chapter in the Handbook of Logic in Artificial Intelligence and Logic Programming (Dov Gabbay et al, editors). Click here for bibliographic and ordering information.
Michael Thielscher, from the Technical University of Darmstadt, has analyzed and compared in his paper An Analysis of Systematic Approaches to Reasoning about Actions and Change the Features and Fluents framework and the Action Description Language A developed by M. Gelfond and V. Lifschitz. He has presented two equivalence results for ontological subclasses and elaborated the major differences. The ultimate aim of his analysis shall be a proposal about a combination of the two frameworks to obtain a powerful semantics which profits from the merits of both the FFF approach as well as the Action Description Language.
Choong-ho Yi has completed his licentiate thesis Reasoning about Concurrent Actions in the Trajectory Semantics. He generalizes the FFF underlying semantics to allow for concurrent actions, even in the case of actions with extended duration. This means that actions may occupy intervals of time that overlap in non-trivial manners, and that intermediate effects of one action may influence the latter part of the execution of another action. He investigates the range of applicability of prototypical chronological minimization with and without filtering, and shows that it is correct under the conditions which apply for sequential actions, provided that the actions do not interact. The thesis will be defended on March 24, 1995.
A summary of Choong-ho Yi's results appears in the article Towards the assessment of logics for concurrent actions, which will be presented at the 1995 AAAI Spring Symposium.
Doherty then showed, in Reasoning about actions and change using occlusion (presented at ECAI 1994), how the circumscriptive version of PMON can be reduced to a first-order formulation. PMON is one of the most general methods that were assessed in Features and Fluents. For a detailed technical report on PMON and its extensions, see Doherty, Notes on PMON Circumscription . [Click here for abstract only]. A significant generalization of the method used by Doherty will be presented at IJCAI-95 in a joint article between Doherty, Lukaszewicz, and Szalas. For an extended technical report, see Computing Circumscription Revisited: A Reduction Algorithm . [Click here for abstract only]. They provide a general algorithm which can be used in an algorithmic manner to reduce circumscription axioms to 1st-order formulas. The class of 2nd-order formulas, and analogously the class of circumscriptive theories which can be reduced, provably subsumes those covered by existing results. The article demonstrates the generality of the algorithm using circumscriptive theories with mixed quantifiers, variable constants, non-separate formulas, and formulas with n-ary predicate variables. It also analyzes the strength of the algorithm and compares it with existing approaches providing formal subsumption results.
Pavlos Peppas, who has visited from Macquarie University, Australia during three months, has completed a departmental report with the title Epistemic Entrenchment and the Possible Models Approach. [Click here for abstract only].
The following are pointers to the home pages for some other research groups that address the same topic: reasoning about actions and change.
Stanford: John McCarthy.
From Fangzhen Lin: The following papers are available in
http://ftp.cs.toronto.edu/pub/cogrob/README.html or ftp://ftp.cs.toronto.edu/pub/cogrob/(Only accessible as ftp). Comments are welcome. This is a link to the above html address, but it is not operational at present.
Erik Sandewall: An Approach to the Frame Problem, and its Implementation. In Machine Intelligence, Vol. 7, pp. 195-204. Edinburgh University Press, 1972.
Erik Sandewall: Non-monotonic entailment for reasoning about time and action. Technical report in three parts. Department of Computer and Information Science, Linköping University, 1988.
Erik Sandewall: A decision procedure for a theory of actions and plans. In Zbigniew Ras (ed): Methodologies for Intelligent Systems, Vol. IV. North-Holland, 1989.
Erik Sandewall: Filter Preferential Entailment for the Logic of Action in almost Continuous Worlds. International Joint Conference on Artificial Intelligence, 1989.
Erik Sandewall: Systematic assessment of temporal reasoning methods for use in autonomous agents. In Zbigniew Ras (ed): Methodologies for Intelligent Systems, Vol. VI, pp. 558-570, North-Holland, 1993
Erik Sandewall: The role of temporal reasoning subsystems in the architecture of autonomous robots. In G. Rzevski et al. (eds): Artificial Intelligence in Engineering, Vol. VIII, pp. 3-6. Computational Mechanics Publications/ Elsevier, 1993.
Erik Sandewall: Nonmonotonic temporal logics and autonomous agents: each contributes to the rigorous basis of the other. In O. Herzog et al (eds): Grundlagen und Anwendungen der Kuenstlichen Intelligenz. Proceedings of the German A.I. conference. Springer Verlag, 1993.