 In a dispositional account, clause (ii) is strengthened by requiring a dispositional relation between the physical states: for any computational state transition of the form s1 → s2 (specified by a computational description), if the system is in the physical state p1 that maps onto s1, the system manifests a disposition whose manifestation is the transition from p1 to the physical state p2 that maps onto s2 (Klein 2008). The physical system is such that physical state p1 (which maps onto computational state s1) manifests the disposition to transition to physical state p2 (which maps onto computational state s2). In other words, the dispositional account requires the mapping between computational and physical descriptions to be such that the dispositional relations between the physical states are isomorphic to the state transitions specified by the computational description. Thus, according to the dispositional account, concrete computation is the dispositional structure of a physical process.