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Automatsko određivanje vrsta riječi u morfološki složenom jeziku / Automatic parts of speech determination in amorphologically complex language

<p>Istraţivanje je imalo za cilj da provjeri u<br />kojoj mjeri se na&scaron; kognitivni sistem moţe<br />osloniti na fonotaktiĉke informacije, tj.<br />moguće/dozvoljene kombinacije fonema/<br />grafema, u zadacima automatske percepcije i<br />produkcije rijeĉi u jezicima sa bogatom<br />infleksionom morfologijom.<br />Da bi se dobio odgovor na to pitanje,<br />sprovedene su tri studije. U prvoj studiji, uz<br />pomoć ma&scaron;ina sa vektorima podr&scaron;ke (SVM),<br />obavljena je diskriminacija promjenljivih<br />vrsta rijeĉi. U drugoj studiji, produkcija<br />infleksionih oblika rijeĉi izvedena je<br />pomoću uĉenja zasnovanog na memoriji<br />(MBL). Na osnovu rezultata iz druge studije,<br />izveden je eksperiment u kojem se traţila<br />potvrda kognitivne vjerodostojnosti modela i<br />kori&scaron;ćenih informacija.<br />Diskriminacija promjenljivih vrsta rijeĉi<br />obavljena je na osnovu dozvoljenih sekvenci<br />dva i tri grafema/fonema (tzv. bigrama i<br />trigrama), ĉije su frekvencije javljanja<br />unutar pojedinaĉnih gramatiĉkih tipova<br />izraĉunate u zavisnosti od njihovog poloţaja<br />u rijeĉima: na poĉetku, na kraju, unutar<br />rijeĉi, svi zajedno. Maksimalna taĉnost se<br />kretala oko 95% i dobijena je na svim<br />bigramima, uz pomoć RBF jezgrene<br />funkcije. Ovako visok procenat taĉne<br />diskriminacije ukazuje da postoje<br />karakteristiĉne distribucije bigrama za<br />razliĉite vrste promjenljivih rijeĉi. S druge<br />strane, najmanje informativnim su se<br />pokazali bigrami na kraju i na poĉetku rijeĉi.<br />MBL model iskori&scaron;ćen je u zadatku<br />automatske infleksione produkcije, tako &scaron;to<br />je za zadatu rijeĉ, na osnovu fonotaktiĉkih<br />informacija iz posljednja ĉetiri sloga,<br />generisan traţeni infleksioni oblik. Na<br />uzorku od 89024 promjenljivih rijeĉi uzetih<br />iz Frekvencijskog reĉnika dnevne &scaron;tampe<br />srpskog jezika, koristeći metod izostavljanja<br />jednog primjera i konstantu veliĉinu skupa<br />susjeda (k = 7), ostvarena je taĉnost oko<br />92%. Identifikovano je nekoliko faktora koji<br />su uticali na ovu taĉnost, kao &scaron;to su: vrsta<br />rijeĉi, gramatiĉki tip, naĉin tvorbe i broj<br />primjera u okviru jednog gramatiĉkog tipa,<br />broju izuzetaka, broj fonolo&scaron;kih alternacija<br />itd.<br />U istraţivanju na subjektima, u zadatku<br />leksiĉke odluke, za rijeĉi koje je MBL<br />pogre&scaron;no obradio utvrĊeno je duţe vrijeme<br />obrade. Ovo ukazuje na kognitivnu<br />vjerodostojnost uĉenja zasnovanog na<br />memoriji. Osim toga, potvrĊena je i<br />kognitivna vjerodostojnost fonotaktiĉkih<br />informacija, ovaj put u zadatku<br />razumijevanja jezika.<br />Sveukupno, nalazi dobijeni u ove tri studije<br />govore u prilog teze o znaĉajnoj ulozi<br />fonotaktiĉkih informacija u percepciji i<br />produkciji morfolo&scaron;ki sloţenih rijeĉi.<br />Rezultati, takoĊe, ukazuju na potrebu da se<br />ove informacije uzmu u obzir kada se<br />diskutuje pojavljivanje većih jeziĉkih<br />jedinica i obrazaca.</p> / <p>The study was aimed at testing the extent to<br />which our cognitive system can rely on<br />phonotactic information, i.e., possible/<br />permissible combinations of phonemes/<br />graphemes, in the tasks of automatic<br />processing and production of words in<br />languages with rich inflectional<br />morphology.<br />In order to obtain the answer to this<br />question, three studies have been conducted.<br />In the first study, by applying the support<br />vector machines (SVM) the discrimination<br />of part of speech (PoS) with more than one<br />possible meaning (i.e., ambiguous PoS) was<br />performed. In the second study, the<br />production of inflected word forms was<br />done with memory based learning (MBL).<br />Based on the results from the second study,<br />a behavioral experiment was conducted as<br />the third study, to test cognitive plausibility<br />of the MBL performance.<br />The discrimination of ambiguous PoS was<br />performed using permissible sequences of<br />two and three characters/sounds (i.e.,<br />bigrams and trigrams), whose frequency of<br />occurrence within individual grammatical<br />types was calculated depending on their<br />position in a word: at the beginning, at the<br />end, and irrespective of position in a word.<br />Maximum accuracy achieved was<br />approximatelly 95%. It was obtained when<br />bigrams irrespective of position in a word<br />were used. SVM model used RBF kernel<br />function. Such high accuracy suggests that<br />brigrams&#39; probability distribution is<br />informative about the types of flective<br />words. Interestingly, the least informative<br />were bigrams at the end and at the beginning<br />of words.<br />The MBL model was used in the task of<br />automatic production of inflected forms,<br />utilizingphonotactic information from the<br />last four syllables. In a sample of 89024<br />flective words, taken from the Frequency<br />dictionary of Serbian language (daily press),<br />achieved accuracy was 92%. For this result<br />the MBL used leave<br />-one<br />-out method and nearest neighborhood size of 7 (k = 7). We</p><p>identified several factors that have<br />contributed to the accuracy; in particular,<br />part of speech, grammatical type, formation<br />method and number of examples within one<br />grammatical type, number of exceptions, the<br />number of phonological alternations, etc.<br />The visual lexical decision experiment<br />revealed that words that the MBL model<br />produced incorrectly also induced elongated<br />reaction time latencies. Thus, we concluded<br />that the MBL model might be cognitively<br />plausibile. In addition, we reconfirmed<br />informativeness of phonotactic information,<br />this time in human conmprehension task.<br />Overall, findings from three undertaken<br />studies are in favor of phonotactic<br />information for both processing and<br />production of morphologically complex<br />words. Results also suggest a necessity of<br />taking into account this information when<br />discussing emergence of larger units and<br />language patterns.</p>

Identiferoai:union.ndltd.org:uns.ac.rs/oai:CRISUNS:(BISIS)94868
Date24 July 2015
CreatorsDimitrijević Strahinja
ContributorsMilin Petar, Filipović-Đurđević Dušica, Kostić Aleksandar
PublisherUniverzitet u Novom Sadu, Filozofski fakultet u Novom Sadu, University of Novi Sad, Faculty of Philosophy at Novi Sad
Source SetsUniversity of Novi Sad
LanguageSerbian
Detected LanguageEnglish
TypePhD thesis

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