 Another variant of the same recipe is called credibility-limited revision. It is based on the assumption that some inputs are accepted, others not. Those that are accepted form the set C of credible sentences. If \(p \in\) C, then \(K?p = K* p\). Otherwise, \(K?p = K\). This construction can be further specified by choosing an operation of revision and assigning properties to the set C. A variety of such constructions have been investigated (Hansson et al. 2001).