Results 1  10
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122
Training Tree Transducers
 IN HLTNAACL
, 2004
"... Many probabilistic models for natural language are now written in terms of hierarchical tree structure. Treebased modeling still lacks many of the standard tools taken for granted in (finitestate) stringbased modeling. The theory of tree transducer automata provides a possible framework to ..."
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Cited by 128 (11 self)
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Many probabilistic models for natural language are now written in terms of hierarchical tree structure. Treebased modeling still lacks many of the standard tools taken for granted in (finitestate) stringbased modeling. The theory of tree transducer automata provides a possible framework to draw on, as it has been worked out in an extensive literature. We motivate the use of tree transducers for natural language and address the training problem for probabilistic treetotree and treetostring transducers.
Characterizing Structural Descriptions Produced By Various Grammatical Formalisms
 IN PROCEEDINGS OF THE 25TH ANNUAL MEETING OF THE ASSOCIATION FOR COMPUTATIONAL LINGUISTICS
, 1987
"... We consider the structural descriptions produced by various grammatical formalisms in terms of the complexity of the paths and the relationship between paths in the sets of structural descriptions that each system can generate. In considering the relationship between formalisms, we show that it is u ..."
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Cited by 98 (9 self)
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We consider the structural descriptions produced by various grammatical formalisms in terms of the complexity of the paths and the relationship between paths in the sets of structural descriptions that each system can generate. In considering the relationship between formalisms, we show that it is useful to abstract away from the details of the formalism, and examln the nature of their derivation process as reflected by properties of their derivation trees. We find that several of the formalisms considered can be seen as being closely related since they have derivation ee sets with the same structure as those produced by ContextFree Grammars. On the basis of this observation, we describe a class of formalisms which we call Linear Context Free Rewritin Systems, and show they are recognizable in polynomial time and generate only semilinear languages.
An Overview of Probabilistic Tree Transducers for Natural Language Processing
, 2005
"... Probabilistic finitestate string transducers (FSTs) are extremely popular in natural language processing, due to powerful generic methods for applying, composing, and learning them. Unfortunately, FSTs are not a good fit for much of the current work on probabilistic modeling for machine translati ..."
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Cited by 71 (6 self)
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Probabilistic finitestate string transducers (FSTs) are extremely popular in natural language processing, due to powerful generic methods for applying, composing, and learning them. Unfortunately, FSTs are not a good fit for much of the current work on probabilistic modeling for machine translation, summarization, paraphrasing, and language modeling. These methods operate directly on trees, rather than strings. We show that tree acceptors and tree transducers subsume most of this work, and we discuss algorithms for realizing the same benefits found in probabilistic string transduction.
A Formal Model for an Expressive Fragment of XSLT
, 2000
"... The extension of the XSL (eXtensible Style sheet Language) by variables and passing of data values between template rules has generated a powerful XML query language: XSLT (eXtensible Style sheet Language Transformations). An informal introduction to XSTL is given, on the bases of which a formal ..."
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Cited by 65 (17 self)
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The extension of the XSL (eXtensible Style sheet Language) by variables and passing of data values between template rules has generated a powerful XML query language: XSLT (eXtensible Style sheet Language Transformations). An informal introduction to XSTL is given, on the bases of which a formal model of a fragment of XSLT is defined. This formal model is in the spirit of tree transducers, and its semantics is defined by rewrite relations. It is shown that the expressive power of the fragment is already beyond that of most other XML query languages. Finally, important properties such as termination and closure under composition are considered.
Bottomup and Topdown Tree Series Transformations
 J. Autom. Lang. Combin
, 2000
"... We generalize bottomup tree transducers and topdown tree transducers to the concept of bottomup tree series transducer and topdown tree series transducer, respectively, by allowing formal tree series as output rather than trees, where a formal tree series is a mapping from output trees to some s ..."
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Cited by 37 (6 self)
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We generalize bottomup tree transducers and topdown tree transducers to the concept of bottomup tree series transducer and topdown tree series transducer, respectively, by allowing formal tree series as output rather than trees, where a formal tree series is a mapping from output trees to some semiring. We associate two semantics with a tree series transducer: a mapping which transforms trees into tree series (for short: tree to tree series transformation or tts transformation), and a mapping which transforms tree series into tree series (for short: tree series transformation or tsts transformation). We show that the standard case of tree transducers is reobtained by choosing the boolean semiring under the tts semantics. Also, for each of the two types of tree series transducers and for both types of semantics, we prove a characterization which generalizes in a straightforward way the corresponding characterization result for the underlying tree transducer class. Mo...
A comparison of pebble tree transducers with macro tree transducers
 Acta Informatica
, 2003
"... Abstract. The npebble tree transducer was recently proposed as a model for XML query languages. The four main results on deterministic transducers are: First, (1) the translation τ of an npebble tree transducer can be realized by a composition of n + 1 0pebble tree transducers. Next, the pebble t ..."
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Cited by 37 (8 self)
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Abstract. The npebble tree transducer was recently proposed as a model for XML query languages. The four main results on deterministic transducers are: First, (1) the translation τ of an npebble tree transducer can be realized by a composition of n + 1 0pebble tree transducers. Next, the pebble tree transducer is compared with the macro tree transducer, a wellknown model for syntaxdirected semantics, with decidable type checking. The 0pebble tree transducer can be simulated by the macro tree transducer, which, by the first result, implies that (2) τ can be realized by an (n+1)fold composition of macro tree transducers. Conversely, every macro tree transducer can be simulated by a composition of 0pebble tree transducers. Together these simulations prove that (3) the composition closure of npebble tree transducers equals that of macro tree transducers (and that of 0pebble tree transducers). Similar results hold in the nondeterministic case. Finally, (4) the output languages of deterministic npebble tree transducers form a hierarchy with respect to the number n of pebbles. 1
THE POWER OF EXTENDED TOPDOWN TREE TRANSDUCERS
"... Extended topdown tree transducers (transducteurs generalises descendants [Arnold, Dauchet: Bitransductions de forets. ICALP'76. Edinburgh University Press. 1976]) received renewed interest in the field of Natural Language Processing. Here those transducers are extensively and systematically s ..."
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Cited by 36 (23 self)
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Extended topdown tree transducers (transducteurs generalises descendants [Arnold, Dauchet: Bitransductions de forets. ICALP'76. Edinburgh University Press. 1976]) received renewed interest in the field of Natural Language Processing. Here those transducers are extensively and systematically studied. Their main properties are identified and their relation to classical topdown tree transducers is exactly characterized. The obtained properties completely explain the Hasse diagram of the induced classes of tree transformations. In addition, it is shown that most interesting classes of transformations computed by extended topdown tree transducers are not closed under composition.
Exact XML type checking in polynomial time
 In ICDT
, 2007
"... f on valid inputs conform to theoutput type? Since XML types are intrinsically more complex than the types found in ..."
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Cited by 34 (3 self)
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f on valid inputs conform to theoutput type? Since XML types are intrinsically more complex than the types found in
Benefits of Tree Transducers for Optimizing Functional Programs
 In FST & TCS'98, Chennai, India, Proceedings, volume 1530 of LNCS
, 1998
"... We present a technique to prevent the construction of intermediate data structures in functional programs, which is based on results from the theory of tree transducers. We first decompose function definitions, which correspond to macro tree transducers, into smaller pieces. Under certain restrictio ..."
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Cited by 32 (6 self)
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We present a technique to prevent the construction of intermediate data structures in functional programs, which is based on results from the theory of tree transducers. We first decompose function definitions, which correspond to macro tree transducers, into smaller pieces. Under certain restrictions...