4 papers
Distance Semantics for Belief Revision
Daniel Lehmann, Menachem Magidor, Karl Schlechta
A vast and interesting family of natural semantics for belief revision is defined. Suppose one is given a distance d between any two models. One may then define the revision of a t…
What does a conditional knowledge base entail?
Daniel Lehmann, Menachem Magidor
This paper presents a logical approach to nonmonotonic reasoning based on the notion of a nonmonotonic consequence relation. A conditional knowledge base, consisting of a set of co…
Nonmonotonic Reasoning, Preferential Models and Cumulative Logics
Sarit Kraus, Daniel Lehmann, Menachem Magidor
Many systems that exhibit nonmonotonic behavior have been described and studied already in the literature. The general notion of nonmonotonic reasoning, though, has almost always b…
Length of Boolean algebras and ultraproducts
Menachem Magidor, Saharon Shelah
We prove the consistency with ZFC of ``the length of an ultraproduct of Boolean algebras is smaller than the ultraproduct of the lengths''. Similarly for some other cardinal invari…