Belief Revision and Verisimilitude

Belief Revision and Verisimilitude Mark Ryan Department of Mathematics Instituto Superior T ecnico Av. Rovisco Pais 1096 Lisbon Codex Portugal mdr@inesc.pt Pierre-Yves Schobbens Institut d'Informatique Fac. Univ. Notre-Dame de la Paix Rue Grandgagnage 21 5000 Namur Belgium pys@info.fundp.ac.be Abstract. The Egli-Milner power-ordering is used to de ne verisimilitude orderings on theories from preference orderings on models. The e ects of the de nitions on constraints such as stopperedness and soundness are explored. Orderings on theories are seen to contain more information than orderings on models. Belief revision is de ned in terms of both types of orderings, and conditions are given which make the two notions coincide.

[1]  David Makinson,et al.  General Theory of Cumulative Inference , 1988, NMR.

[2]  C. Brink,et al.  A Verisimilar Ordering of Theories Phrased in a Propositional Language , 1987, The British Journal for the Philosophy of Science.

[3]  Pierre-Yves Schobbens,et al.  specifications: on the meaning of "but" , 1993 .

[4]  Sarit Kraus,et al.  Nonmonotonic Reasoning, Preferential Models and Cumulative Logics , 1990, Artif. Intell..

[5]  Editors , 1986, Brain Research Bulletin.

[6]  Yoav Shoham,et al.  A semantical approach to nonmonotonic logics , 1987, LICS 1987.

[7]  Michael Reinfrank,et al.  Non-Monotonic Reasoning , 1989, Lecture Notes in Computer Science.

[8]  Karl Schlechta,et al.  Some Results on Classical Preferential Models , 1992, J. Log. Comput..

[9]  P G rdenfors,et al.  Knowledge in flux: modeling the dynamics of epistemic states , 1988 .

[10]  J. Davenport.  Editor , 1960 .

[11]  B. J. Mason,et al.  Closer to the Truth , 1985 .

[12]  Mark Ryan,et al.  Defaults and revision in structured theories , 1991, [1991] Proceedings Sixth Annual IEEE Symposium on Logic in Computer Science.

[13]  Chris Brink,et al.  Verisimilitude: views and reviews , 1989 .

[14]  K. Popper,et al.  Conjectures and Refutations , 1963 .

[15]  Peter Gärdenfors,et al.  Relations between the logic of theory change and nonmonotonic logic , 1989, The Logic of Theory Change.