Weighted Monadic Datalog Tree Transducers

Multioperator Weighted Monadic Datalog

Querying Unranked Trees with Stepwise Tree Automata

The problem of selecting nodes in unranked trees is the most basic querying problem for XML. We propose stepwise tree automata for querying unranked trees. Stepwise tree automata can express the same monadic queries as monadic Datalog and monadic second-order logic. We prove this result by reduction to the ranked case, via a new systematic correspondence that relates unranked and ranked queries.

A note on monadic datalog on unranked trees

In the article Recursive queries on trees and data trees (ICDT’13), Abiteboul et al. asked whether the containment problem for monadic datalog over unordered unranked labeled trees using the child relation and the descendant relation is decidable. This note gives a positive answer to this question, as well as an overview of the relative expressive power of monadic datalog on various representat...

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 ...

Domains of Partial Attributed Tree Transducers Domains of Partial Attributed Tree Transducers

The domains of partial attributed tree transducers (patt's) are the tree languages recognized by tree walking automata in universal acceptance mode. Moreover, the domains of patt's having monadic output are the tree languages recognized by deter-ministic tree walking automata.