Converging to the Chase -- A Tool for Finite Controllability

We solve a problem, stated in [CGP10], showing that Sticky Datalog
^∃
, defined in the cited paper as an element of the Datalog
^±
project, has the finite controllability property. In order to do that, we develop a technique, which we believe can have further applications, of approximating Chase(D, T), for a database instance D and a set of tuple generating dependencies and datalog rules T, by an infinite sequence of finite structures, all of them being models of T and D.