Compositions with superlinear deterministic top-down tree transformations
نویسندگان
چکیده
منابع مشابه
Compositions of Extended Top-down Tree Transducers
Unfortunately, the class of transformations computed by linear extended top-down tree transducers with regular look-ahead is not closed under composition. It is shown that the class of transformations computed by certain linear bimorphisms coincides with the previously mentioned class. Moreover, it is demonstrated that every linear epsilon-free extended top-down tree transducer with regular loo...
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Top-down tree transducers with "-rules ("tdtt) are a restricted version of extended top-down tree transducers. They are implemented in the framework Tiburon and ful ll some criteria desirable in a machine translation model. However, they compute a class of transformations that is not closed under composition (not even for linear and nondeleting "tdtt). A composition construction that composes "...
متن کاملDeterministic Top-Down Tree Transducers with Iterated Lookahead
It is known that by iterating the look-ahead tree languages for deterministic topdown tree automata, more and more powerful recognizing devices are obtained. Let DR0 = DR, where DR is the class of all tree languages recognizable by deterministic top-down tree automata, and let, for n 1, DRn be the class of all tree languages recognizable by deterministic top-down tree automata with DRn 1 lookah...
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Many aspects of machine translation of natural languages can be formalized by employing weighted finite-state (string) transducers [22, 40]. Successful implementations based on this wordor phrasebased approach are, for example, the At&t Fsm toolkit [41], Xerox’s finite-state calculus [24], the Rwth toolkit [23], Carmel [19], and OpenFst [2]. However, the phrase-based approach is not expressive ...
متن کاملNode Query Preservation for Deterministic Linear Top-Down Tree Transducers
This paper discusses the decidability of node query preservation problems for XML document transformations. We assume a transformation given by a deterministic linear top-down data tree transducer (abbreviated as DLTV ) and an n-ary query based on runs of a tree automaton. We say that a DLTV Tr strongly preserves a query Q if there is a query Q′ such that for every document t, the answer set of...
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ژورنال
عنوان ژورنال: Theoretical Computer Science
سال: 1998
ISSN: 0304-3975
DOI: 10.1016/s0304-3975(96)00332-5