N-Ary Queries by Tree Automata
نویسندگان
چکیده
N -ary queries in trees select sets of n-tuples of nodes. We propose and investigate representation formalisms for n-ary queries by tree automata, both for ranked and unranked trees. We show that existential run-based queries capture MSO in the n-ary case, as well as universal run-based queries. We then characterize queries by runs of unambiguous tree automata, and show how to decide whether an MSO defined query belongs to this class.
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