Containment of Monadic Datalog

Talk by Pierre Bourhis

Location: APB 0005
Start: 4. November 2014 at 1:30 pm
End: 4. November 2014 at 2:30 pm
Research group: Computational Logic
Research group: Automata Theory
Research group: Knowledge-Based Systems
iCal

We reconsider the problem of containment of monadic datalog (MDL) queries in unions of conjunctive queries (UCQs). Prior work has dealt with special cases, but has left the precise complexity characterization open. We begin by establishing a 2EXPTIME lower bound on the MDL/UCQ containment problem, resolving an open problem from the early 90’s. We then present a general approach for getting tighter bounds on the complexity, based on analysis of the number of mappings of queries into tree-like instances. We use the machinery to present an important case of the MDL/UCQ containment problem that is in co-NEXPTIME, and a case that is in EXPTIME. We then show that the technique can be used to get a new tight upper bound for containment of tree automata in UCQs. We show that the new MDL/UCQ upper bounds are tight.

More info at: http://www.lifl.fr/~bourhis/pierre.en.html