Views
5 years ago

Lexicalized Stochastic Modeling of Constraint-Based Grammars ...

Lexicalized Stochastic Modeling of Constraint-Based Grammars ...

Lexicalized Stochastic Modeling of Constraint-Based Grammars

InProceedingsofthe38thAnnualMeetingortheACL,2000,HongKong. LexicalizedStochasticModelingofConstraint-BasedGrammars usingLog-LinearMeasuresandEMTraining StefanRiezler IMS,UniversitätStuttgart riezler@ims.uni-stuttgart.de DetlefPrescher IMS,UniversitätStuttgart prescher@ims.uni-stuttgart.de JonasKuhn IMS,UniversitätStuttgart jonas@ims.uni-stuttgart.de MarkJohnson Cog.&Ling.Sciences,BrownUniversity Mark_Johnson@brown.edu Abstract Wepresentanewapproachto stochasticmodelingofconstraint- basedgrammarsthatisbasedonlog- linearmodelsandusesEMforesti- mationfromunannotateddata.The techniquesareappliedtoanLFG grammarforGerman.Evaluationon anexactmatchtaskyields86%pre- cisionforanambiguityrateof5.4, and90%precisiononasubcatframe matchforanambiguityrateof25. Experimentalcomparisontotrain- ingfromaparsebankshowsa10% gainfromEMtraining.Also,anew class-basedgrammarlexicalizationis presented,showinga10%gainover unlexicalizedmodels. 1Introduction Stochasticparsingmodelscapturingcontex- tualconstraintsbeyondthedependenciesof probabilisticcontext-freegrammars(PCFGs) arecurrentlythesubjectofintensiveresearch. Aninterestingfeaturecommontomostsuch modelsistheincorporationofcontextualde- pendenciesonindividualheadwordsintorule- basedprobabilitymodels.Suchword-based lexicalizationsofprobabilitymodelsareused successfullyinthestatisticalparsingmod- elsof,e.g.,Collins(1997),Charniak(1997), orRatnaparkhi(1997).However,itisstill anopenquestionwhichkindoflexicaliza- tion,e.g.,statisticsonindividualwordsor statisticsbaseduponwordclasses,isthebest choice.Secondly,theseapproacheshavein commonthefactthattheprobabilitymodels aretrainedontreebanks,i.e.,corporaofman- uallydisambiguatedsentences,andnotfrom corporaofunannotatedsentences.Inallofthe citedapproaches,thePennWallStreetJour- nalTreebank(Marcusetal.,1993)isused, theavailabilityofwhichobviatesthestandard eortrequiredfortreebanktraininghand- annotatinglargecorporaofspecicdomains ofspeciclanguageswithspecicparsetypes. Moreover,commonwisdomisthattraining fromunannotateddataviatheexpectation- maximization(EM)algorithm(Dempsteret al.,1977)yieldspoorresultsunlessat leastpartialannotationisapplied.Experi- mentalresultsconrmingthiswisdomhave beenpresented,e.g.,byElworthy(1994)and PereiraandSchabes(1992)forEMtraining ofHiddenMarkovModelsandPCFGs. Inthispaper,wepresentanewlexicalized stochasticmodelforconstraint-basedgram- marsthatemploysacombinationofhead- wordfrequenciesandEM-basedclustering forgrammarlexicalization.Furthermore,we makecrucialuseofEMforestimatingthe parametersofthestochasticgrammarfrom unannotateddata.OurusageofEMwasini- tiatedbythecurrentlackoflargeunication- basedtreebanksforGerman.However,ourex- perimentalresultsalsoshowanexceptionto thecommonwisdomoftheinsuciencyofEM forhighlyaccuratestatisticalmodeling. Ourapproachtolexicalizedstochasticmod- elingisbasedontheparametricfamilyoflog- linearprobabilitymodels,whichisusedtode- neaprobabilitydistributionontheparses ofaLexical-FunctionalGrammar(LFG)for German.Inpreviousworkonlog-linearmod- elsforLFGbyJohnsonetal.(1999),pseudo-

Constraints based modeling as a mean to link dialectical ... - IFIP
An Application of Lexicalized Grammars in English ... - CiteSeerX
Modelling Underlying Energy Demand Trends and Stochastic ...
an application of the stochastic trend model to UK energy demand
Estimating the Parameters of Stochastic Volatility Models using ...
Stochastic Modeling Workshop — Economic Scenarios
Simulated Maximum Likelihood in Stochastic Volatility Modelling
A Stochastic Model of Selective Visual Attention ... - ResearchGate
Stochastic Model of Inhabitant Behaviour - Ecbcs
A Computational Study of Stochastic Models in Finance
[+]The best book of the month Stochastic Modeling in Economics and Finance (Applied Optimization) [FULL]
Assessment of deterministic and stochastic multi-model ... - Nato
Multiscale stochastic modeling in polycrystalline materials ...
Probabilistic And Stochastic UML Statecharts - Software Modeling ...
Factored grammar and performance models - EALing - Ens
Some Simple Stochastic Models for Analyzing Investment Guarantees
Applying stochastic volatility models for pricing and hedging ...
Constraint-based Modeling: Part II - Systems Biology Research Group
Structural Credit Risk Model with Stochastic Volatility: A Particle-filter ...
Characteristics & Performance of GOCE based Gravity Field Models
New Releases Monte Carlo Methods in Financial Engineering (Stochastic Modelling and Applied Probability): Volume 53 Any Format
Tools for Geospatial and Agent Based Modeling to Evaluate Climate ...
Tools for Geospatial and Agent Based Modeling to Evaluate Climate ...
Best ebook Stochastic Calculus for Finance I: The Binomial Asset Pricing Model (Springer Finance / Springer Finance Textbooks): v. 1 Unlimited
Characteristics & Performance of GOCE based Gravity Field Models
Lexicalized Stochastic Modeling of Constraint-Based Grammars ...
A model of lexical variation and the grammar with application to ...
Range Based Estimation of Stochastic Volatility Models
A model of syntactic disambiguation based on lexicalized ... - CLAIR