“…Hence, any such conclusion may be retracted when new facts are added to the agent's knowledge. For this reason, many nonmonotonic modal formalisms have been proposed in order to characterize the reasoning abilities of an introspective agent: among them, we recall the nonmonotonic modal logics originally proposed by McDermott and Doyle [32,31,30], Moore's autoepistemic logic [35], Lifschitz's logic of minimal knowledge and negation as failure MKNF/MBNF [26,27], Levesque's logic of only knowing [24], and ground nonmonotonic modal logics [18,9,46]. …”