Variable independence in constraint databases
In this paper, we study constraint databases with variable independence conditions (vics). Such databases occur naturally in the context of temporal and spatiotemporal database applications. Using computational geometry techniques, we show that variable independence is decidable for linear constraint databases, We also present a set of rules for inferring vics in relational algebra expressions. Using vics, we define a subset of relational algebra that is closed under restricted aggregation.
constraint databases spatiotemporal databases aggregation closure integrity constraints