 Plausibility models are used to represent more nuanced versions of knowledge and belief. These models are also used to reason about static belief changes. The idea behind plausibility models is similar to that for our basic Kripke models: each agent considers various worlds as possible candidates for the actual one. However, there is a key difference: among any two worlds w and v that an agent a considers possible, she imposes a relative plausibility order. The plausibility order for agent a is denoted by \(\geq_a\). We write 