A More General Theory of Static Approximations for Conjunctive Queries
ICDT, pp. 7:1-7:22, 2018.
Conjunctive query (CQ) evaluation is NP-complete, but becomes tractable for fragments of bounded hypertreewidth. If a CQ is hard to evaluate, it is thus useful to evaluate an approximation of it in such fragments. While underapproximations (i.e., those that return correct answers only) are well-understood, the dual notion of overapproxima...More
PPT (Upload PPT)