Recall in extensive form games

This paper considers characterizations of perfect recall in extensive form games. It is shown that perfect recall can be expressed in terms of choices without any reference to infomation sets. When information sets are taken into account, it is decomposable into an ordering of information sets and t hat players do not forget what they knew nor what they did. Thus, if inform ation sets are partially ordered, then perfect recall is implied by the pla yer's inability to refine her information from the memory.