Analytic AGM Revision

Since they were introduced, AGM revision and Katsuno and Mendel-zon’s update have been considered esentially different theory change operations serving different purposes. This work provides a new pre-sentation of AGM revision based on the update semantic apparatus establishing in such a way a bridge between the two seemingly incom-parable frameworks. We define a new operation • ̄ as a variant of the standard update that we call an analytic revision. We prove the correspondence between analytic revisions and (transitively relational) AGM revisions when a given fixed theory is considered (Theorem 4.8). Furthermore, we can characterize analytic revision functions for possibly infinite languages as those AGM revisions satisfying (K*1)-(K*8) plus two new postu-lates (LU-∃) and (LU-∀) governing the revision of different theories (Theorem 5.3). We believe these results bring new light to the issue of how revision and update functions are related. They also provide a novel way to achieve iterated theory revision.