Abstract
The complexity of containment and satisfiability of conjunctive queries over finite, unranked, labeled trees is studied with respect to the axes Child, nextSibling, their transitive and reflexive closures, and Following. For the containment problem a trichotomy is presented, classifying the problems as in PTIME, coNP-complete, or Π 2 P-complete. For the satisfiability problem most problems are classified as either in PTIME or NP-complete.
This work was supported by the DFG Grant SCHW678/3-1.
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Björklund, H., Martens, W., Schwentick, T. (2007). Conjunctive Query Containment over Trees. In: Arenas, M., Schwartzbach, M.I. (eds) Database Programming Languages. DBPL 2007. Lecture Notes in Computer Science, vol 4797. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-540-75987-4_5
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DOI: https://doi.org/10.1007/978-3-540-75987-4_5
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