Action theory contraction and minimal change

This work is about changing action domain descriptions in dynamic logic. We here revisit the semantics of ac-tion theory contraction, giving more robust operators that express minimal change based on a notion of dis-tance between models. We then define syntactical con-traction operators and establish their correctness w.r.t. our semantics. Finally we show that our operators sat-isfy the PDL-counterpart of the standard postulates for theory change adopted in the literature