K- U ni M orph: K orean U niversal M orphology and its Feature Schema (2023)

Abstract: We present in this work a new Universal Morphology dataset for Korean. Previously, the Korean language has been underrepresented in the field of morphological paradigms amongst hundreds of diverse world languages. Hence, we propose this Universal Morphological paradigms for the Korean language that preserve its distinct characteristics. For our K-UniMorph dataset, we outline each grammatical criterion in detail for the verbal endings, clarify how to extract inflected forms, and demonstrate how we generate the morphological schemata. This dataset adopts morphological feature schema from CITATION and CITATION for the Korean language as we extract inflected verb forms from the Sejong morphologically analyzed corpus that is one of the largest annotated corpora for Korean. During the data creation, our methodology also includes investigating the correctness of the conversion from the Sejong corpus. Furthermore, we carry out the inflection task using three different Korean word forms: letters, syllables and morphemes. Finally, we discuss and describe future perspectives on Korean morphological paradigms and the dataset.

## introduction the universal morphology (unimorph) project is a collaborative effort providing broad-coverage morphological paradigms for diverse world languages @xcite . uni-morph consists of a lemma and bundle of morphological features related to a particular inflected word form as follows, for example: 나서다naseoda 나섰다naseossda v;decl;pst where 나서다naseoda is the lemma form and 나섰 다naseossda ('became') is the inflected form with v;decl;pst (verb, declarative, and past tense) as morphological schema. it started in 2016 as a sigmorphon shared task @xcite for the problem of morphological reinflection, and it introduced morphological datasets for 10 languages. the inflection task, using the given lemma with its part-of-speech to generate a target inflected form, has been continued through the years: conll-sigmorphon 2017 shared task @xcite , conll-sigmorphon 2018 shared task @xcite , @xcite , sigmorphon 2020 shared task @xcite and @xcite . however, the korean language has not been a part of the shared task because of the lack of the dataset. nonetheless, although rarely, morphological paradigms for korean have been explored in the context of computational linguistics. yongkyoon (1993) defined the inflectional classes for verbs in korean using word-and-paradigm (wp) @xcite approaches. his fifteen classes of the verb which can be joined with seven different types of verbal endings, are based on inflected forms of the verb. @xcite systematized the list of final endings and their properties, which are also used as conjunctive endings in korean. otherwise, properties of verbs such as mood, tense, voice, evidentiality, interrogativity have been extensively studied in korean linguistics independently: for example, inter alia, tense @xcite , grammatical voice @xcite , interaction of tense-aspect-mood marking with modality (jae mog, 1998), evidentiality @xcite , and interrogativity @xcite . in continuation of the efforts, this paper proposes a new universal morphology dataset for korean. we adopt morphological feature schema from @xcite and sylak-glassman (2016) for the korean language and extract inflected verb forms from the sejong morphologi-cally analyzed corpus over 0.6m sentences with 9.5m words. we set the criteria in detail by explaining how to extract inflected verbal forms (section 2), and carry out the inflection task using different korean word forms such as letter, syllable and morpheme (section 3). finally, we discuss future perspectives on a korean unimorph dataset (section 4). ## unimorph features schema verbal endings in the inflected forms of the predicate has been considered as still being in the part of the word as proposed in several grammar formalisms for korean such as lexicalized tree adjoining grammars @xcite , head driven phrase structure grammars @xcite , and combinatory categorial grammars @xcite in contrast to government and binding (gb) theory @xcite for korean in which the entire sentence depends on separated verbal endings. this idea goes back to maurice gross's lexicon grammars @xcite , and his students who worked on a descriptive analysis of korean in which the number of predicates in korean could be fixed by generating possible inflection forms: e.g. @xcite ; @xcite ; @xcite ; @xcite ; @xcite ; @xcite ; @xcite . however, we have separated the postposition from the substantive such as noun phrases instead of keeping themselves together. therefore, with the current korean dataset, we decide to annotate morphological data for verbs (v). evidentiality it is a grammatical category that reflects the source of information that a speaker conveys in a proposition. it is often expressed through morphological markers such as sentence final endings (ef) 대dae, 내nae, and 래lae bring in hearsay (hrsy), and non-final endings (ep) 겠gess introduce inferred (infer). since the suffix for the quotative (quot) is denoted with a postposition (jkq) in korean instead of the verbal ending, it is excluded from the current set of schemata. interrogativity it indicates either to express a statement (decl) or a question (int). we consider all sentence final ending (ef) ended with 다da as declarative decl, and sentence final ending (ef) included 가ga and 까kka as interrogative int. ## discussion and future perspectives we have dealt with unimorph schema for verbs, and obtained experimental results for the morphological reinflection task using the different representation forms of the word. nouns in korean have been considered by separating postposition from the lemma of the noun instead of keeping themselves together (e.g. 프랑스peulangseu ('france') and 의ui ('gen') instead of 프랑스의peulangseuui) in several grammar formalisms for korean. however, in addition to exogenously given interests such as inflection in context, foot_3 recent studies insist the functional morphemes including both ver-bal endings and postpositions in korean should be treated as part of a word, with the result that their categories do not require to be assigned individually in a syntactic level @xcite . accordingly, it would be more efficient to assign the syntactic categories on the fully inflected lexical word derived by the lexical rule of the morphological processes in the lexicon. therefore, we will investigate how we adopt features for nouns such as cases including non-core and local cases such as nom (nominative), acc (accusative), comparison (cmpr), and information structure top (topic) (