Browsing by Subject "two-level morphology"

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  • Koskenniemi, Kimmo (The Association for Computational Linguistics, 1984)
    A language independent model for recognition and production of word forms is presented. This "two-level model" is based on a new way of describing morphological alternations. All rules describing the morphophonological variations are parallel and relatively independent of each other. Individual rules are implemented as finite state automata, as in an earlier model due to Martin Kay and Ron Kaplan. The two-level model has been implemented as an operational computer programs in several places. A number of operational two-level descriptions have been written or are in progress (Finnish, English, Japanese, Rumanian, French, Swedish, Old Church Slavonic, Greek, Lappish, Arabic, Icelandic). The model is bidirectional and it is capable of both analyzing and synthesizing word-forms.
  • Koskenniemi, Kimmo (2013)
    The paper shows how a certain kind of underlying representations (or deep forms) of words can be constructed in a straightforward manner through aligning the surface forms of the morphs of the word forms. The inventory of morphophonemes follows directly from this alignment. Furthermore, the two-level rules which govern the different realisations of such morphophonemes follow fairly directly from the previous steps. The alignment and rules are based upon an approximate general metric among phonemes, e.g., articulatory features, that determines which alternations are likely or possible. This enables us to summarise contexts for the different realisations.
  • Yli-Jyrä, Anssi Mikael (The Association for Computational Linguistics, 2011)
    Paperi kuvaa epäkonventionaalisen menetelmän (fonologisten ja morfo-syntaktisten) kontekstirajoitesääntöjen kääntämiseksi epädeterministisiksi automaateiksi äärellistilaisissa työkaluissa ja pintajäsennysjärjestelmissä. Metodi redusoi minkä tahansa kontekstirajoitteen yksinkertaiseksi rajoitteeksi, joka rajoittaa tyhjän merkkijonon esiintymisiä ja esittää oikean puolen kontekstit takaperindeterminististen tilojen avulla. Tapauksissa, joissa täysin deterministinen esitysmuoto olisi eksponentiaalisesti isompi, tällainen sisäänpäin deterministinen kontekstien esitysmuoto voi olla edullisempi kuin erilaiset De Morgan -lähestymistavat, joissa täysi determinisointi on välttämätöntä. Menetelmän yhteydessä jokainen hyväksytty merkkijono saa yksiselitteisen polun, joka on kontekstien tunnistaja-automaatissa olevan tikapuumaisen rakenteen projektio. Tämä projektio voidaan laskea (koko rajoitteelle) ajassa, joka on polynomisessa suhteessa kontekstitilojen määrään. Menetelmästä voi kuitenkin olla vaikea saada hyötyä, jos sitä käytetään äärellistilaisessa kirjastossa, joka pakottaa välitulokset kanonisiksi automaateiksi ja jonka leikkaus-operaatio edellyttää deterministisiä automaatteja operandeinaan.
  • Yli-Jyrä, Anssi Mikael (Northern European Association for Language Technology, 2011)
    NEALT Proceedings Series
    (översättning:) I dokumentet föreslås morphofonematisk markörer kallas positionwise flaggor. Dessa flaggor är inspirerade av de tekniker som används i sammanställningen av två nivåer regler. Det sammanställer praktiskt taget alla regler parallellt, men på ett effektivt sätt. Tekniken hanterar morphofonematisk processer utan separat morphofonematisk representation. De förekomster av allomorphofonem i latenta fonologiska strängar spåras genom en dynamisk datastruktur där den mest framträdande (dvs. bäst rankade) flaggor samlas in. Tillämpningen av tekniken är misstänkt för att ge fördelar när de beskriver morfologi Bantu språk och dialekter
  • Koskenniemi, Kimmo (Northern European Association for Language Technology, 2013)
    NEALT Proceedings Series
    Regular correspondences between historically related languages can be modelled using finite-state transducers (FST). A new method is presented by demonstrating it with a bidirectional experiment between Finnish and Estonian. An artificial representation (resembling a proto-language) is established between two related languages. This representation, AFE (Aligned Finnish-Estonian) is based on the letter by letter alignment of the two languages and uses mechanically constructed morphophonemes which represent the corresponding characters. By describing the constraints of this AFE using two-level rules, one may construct useful mappings between the languages. In this way, the badly ambiguous FSTs from Finnish and Estonian to AFE can be composed into a practically unambiguous transducer from Finnish to Estonian. The inverse mapping from Estonian to Finnish is mildly ambiguous. Steps according to the proposed method could be repeated as such with dialectal or older written texts. Choosing a set of model words, aligning them, recording the mechanical correspondences and designing rules for the constraints could be done with a limited effort. For the purposes of indexing and searching, the mild ambiguity may be tolerable as such. The ambiguity can be further reduced by composing the resulting FST with a speller or morphological analyser of the standard language.
  • Koskenniemi, Kimmo Matti; Kuutti, Pirkko (Research Institute for Linguistics, Hungarian Academy of Sciences, 2017)
  • Koskenniemi, Kimmo (CSLI publications, 2019)
    CSLI Lecture Notes