Weighted monadic datalog

Multioperator Weighted Monadic Datalog

Weighted Monadic Datalog Tree Transducers

We introduce a weighted tree transducer model that combines aspects of weighted top down tree transducers and monadic datalog; this allows us to specify information transport for non-adjacent nodes in a single rule. We will investigate four different semantics for our weighted tree transducer model and prove that they coincide under certain conditions. We present and prove the correctness of an...

Monadic Datalog Containment

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 tigh...

Monadic Datalog Containment on Trees

We show that the query containment problem for monadic datalog on finite unranked labeled trees can be solved in 2-fold exponential time when (a) considering unordered trees using the axes child and descendant, and when (b) considering ordered trees using the axes firstchild, nextsibling, child, and descendant. When omitting the descendant-axis, we obtain that in both cases the problem is Expti...

Containment of Monadic Datalog Programs via Bounded Clique-Width

Containment of monadic datalog programs over data trees (labelled trees with an equivalence relation) is undecidable. Recently, decidability was shown for two incomparable fragments: downward programs, which never move up from visited tree nodes, and linear childonly programs, which have at most one intensional predicate per rule and do not use descendant relation. As di erent as the fragments ...