EnglishGrammar_HPSG(2)

grammardevelopmentsystemsforwhichsourceisfreelyavailable,ofwhichALE(CarpenterandPenn,1999)hasprobablythewidestdistribution,thegrammarsdistributedwiththemarerelativelysmallcomparedtotheLinGOERG.TheXTAGgrammar(TheXTAGResearchGroup,1995)isofmorecomparablesizetotheLinGOERG,butdoesnotincludesemanticsandtheXTAGparseris“notforthecasualuser”accordingtotheXTAGwebsite.TheLinGOtechnologyisperhapsmoresimilartotheAlveyNaturalLanguageTools(ANLT)(Briscoeetal.,1987),whichhasbeenwidelyusedinNLP.HoweverafeeischargedfortheANLT,theformalismisnotasclosetoacurrentlypopularlinguisticframework,andnogeneratorisavailable.Finally,adistinctivefeatureoftheLinGOef-fortistheunusualdegreeofcross-centerandinternationalcollaboration(seetheacknowledgmentsin6.).In3.wewilldiscussvariousissuesthatarisewhenweattempttofa-cilitatecollaborativedevelopmentandcommonuseoftheresources,but rstwewillgivemoredetailsoftheircurrentstate.

2.TheLinGOresources

2.1.TheLKBsystem:ef cienttechnologyfor

grammardevelopment

TheLKBsystemwasoriginallydevelopedatCam-bridgeUniversityaspartoftheEUACQUILEXprojectsasawayofrepresentingandvalidatinghighlystructuredlexicalinformation(Copestake,1992).Atthispoint,LKBstoodforLexicalKnowledgeBase,andtheLKBsystemwasatoolforconstructionofsuchknowledgebases.Assuch,ef ciencyofparsinglargegrammarswasnotapri-maryconsideration.WhenwedecidedtoutilizetheLKBsystematCSLIasamoregeneraltoolforgrammardevel-opment,severalcorecomponentswerereimplementedandef ciencygreatlyimproved(Maloufetal.,2000;OepenandCarroll,2000).

Aprimaryconsiderationinouref ciencyworkhasbeentoavoidanytechniqueswhichrequirelengthygrammarcompilation.Reasonableef ciencyisessentialforgram-mardevelopmentsystems,sinceitmustbepossibletoquicklyvalidatechangesmadetothegrammaronextensivetestsuites(see3.1.).Butitiscrucialthattheedit-test-debugcyclebekeptasshortaspossible,whichimpliesthatthetimerequiredtoloadandreloadagrammarmustbeshort.TheERGcurrentlyloadsinabout20secondswithacachedlexicon,withaboutanother30secondsbeingnecessaryifthedatabaseusedforthelexiconhastobeconstructedfromscratch.2SomeindicationofparsingtimescanbegatheredfromTable1.

ThefunctionalityoftheLKBsystemhasalsobeenex-tendedinseveralwayssinceitsuseonACQUILEX,mostnotably:

1.semanticprocessingusingMRS(Copestakeetal.,1999),see3.3.

2.additionofanef cienttacticalgenerator(Carrolletal.,1999),