Expansion and Contraction of Finite States

We present a theory that copes with the dynamics of inconsistent information. A method is set forth to represent possibly inconsistent information by a *finite state*. Next, finite operations for expansion and contraction of finite states are given. No extra-logical element -- a choice function or an ordering over (sets of) sentences -- is presupposed in the definition of contraction. Moreover, expansion and contraction are each other's duals. AGM-style characterizations of these operations follow.

	EaCoFS.pdf