FinnishOTProsody - Fi(n)nish OT Prosody Fi(n)nish LauriKarttunen FSMNLP2005 September1,2005 Overview Overview Lexicaltransducers

FinnishOTProsody - Fi(n)nish OT Prosody Fi(n)nish...

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Fi(n)nish OT Prosody Fi(n)nish OT Prosody Lauri Karttunen FSMNLP-2005 September 1, 2005
Overview Overview Success of Finite-State Morphology Lexical transducers Two ways of describing morphological alterations Sequential (Chomsky & Halle 1968) Parallel (Koskenniemi 1983) Optimality Theory (Prince & Smolensky 1993) Yet another two-level model Finite-state? Lenient composition Finnish OT Prosody Basic Facts Finite-state implementation of Kiparsky’s 2003 analysis with the FST tool (Beesley & Karttunen 2003) Conclusion Final thoughts
Computational morphology Computational morphology Analysis leaves leaf N Pl leave N Pl leave V Sg3 Generation hang V Past hanged hung
Two challenges Two challenges Morphotactics Words are composed of smaller elements that  must be combined in a certain order: piti-less-ness  is English piti-ness-less  is not English Phonological alternations The shape of an element may vary depending on  the context pity  is realized as  piti in  pitilessness die  becomes  dy  in  dying
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talked --> talk+Past k : k t : t a:a a : a w:w o:o l : l r:r +Progr:i ε :g +3rdSg:s +Past : e ε : d ε :n +Base: ε Analysis Analysis
Lexical transducer Lexical transducer veut vouloir +IndP +SG + P3 Finite-state transducer inflected form citation form inflection codes v o u l o i r +IndP +SG +P3 v e u t Bidirectional: generation or analysis Compact and fast Comprehensive systems have been  built for over 40 languages: English, German, Dutch, French,  Italian, Spanish, Portuguese,  Finnish, Russian, Turkish,  Japanese, Korean, Basque, Greek,  Arabic, Hebrew, Bulgarian, …
How lexical transducers are made How lexical transducers are made Lexicon FST Rule FSTs Compiler f a t +Adj r +Comp f a t t e Lexical Transducer (a single FST) composition Lexicon Regular Expression Rules Regular Expressions Morphotactics Alternations
Two-level rules vs. rewrite rules Two-level rules vs. rewrite rules co mpose intersect FST rule 1 rule 2 rule n ... Surface form Lexical form Koskenniemi 1983 Intermediate form ... Surface form Lexical form rule 1 rule n rule 1 Chomsky&Halle 1968
Rewrite rules Rewrite rules Epenthesis Harmony Lowering ? u: t y ? A s ? u: t I y ? A s ? u: t u y ? a s ? o: t u y ? a s Yawelmani Vowel Harmony Kisseberth 1969

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