Logical Data Expiration for Fixpoint Extensions of Temporal Logics

摘要

We study the differences between the future and the past fragments of fixpoint extensions of first-order temporal logics in their relationship to expiration of database histories. We show that while the past fragment admits a bounded expiration operator, the future one requires retaining data of size bounded from below by a function linear in the length of the history. We also discuss fragments of future fixpoint temporal logic for which bounded expiration operators can exist.