Pavlos Peppas Samir Chopra Norman Y. Foo Distance Semantics for Relevance-Sensitive Belief Revision. 2007 Formal Models of Belief Change in Rational Agents http://drops.dagstuhl.de/opus/volltexte/2007/1215 conf/dagstuhl/2007P7351 db/conf/dagstuhl/P7351.html#PeppasCF07