Abstract:
Since they were introduced, AGM revision and Katsuno and Mendel-
zon's update have been considered esentially di erent theory change
operations serving di erent 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 de ne 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 xed theory is considered (Theorem 4.8). Furthermore, we can
characterize analytic revision functions for possibly in nite languages
as those AGM revisions satisfying (K*1)-(K*8) plus two new postu-
lates (LU-9) and (LU-8) governing the revision of di erent 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.