Building a U niversal D ependencies Treebank for a Polysynthetic Language: the Case of A baza (2023)

Abstract: In this paper, we discuss the challenges that we faced during the construction of a Universal Dependencies treebank for Abaza, a polysynthetic Northwest Caucasian language. We propose an alternative to the morpheme-level annotation of polysynthetic languages introduced in Park et al. (2021). Our approach aims at reducing the number of morphological features, yet providing all the necessary information for the comprehensive representation of all the syntactic relations. Besides, we suggest to add one language-specific relation needed for annotating repetitions in spoken texts and present several solutions that aim at increasing cross-linguistic comparability of our data.

## introduction the universal dependencies (ud) framework @xcite provides a crosslinguistically universal annotation scheme, which, when necessary, allows language-specific extensions. the need for language-specific extensions becomes particularly evident when building a treebank for languages with polysynthetic morphology (on the features commonly considered polysynthetic, see, e.g., @xcite . for example, to account for nominal incorporation in chukchi, @xcite introduce additional nodes for incorporated arguments of predicates. 1 in the treebank of st. lawrence island yupik, @xcite treat each morpheme as a token which requires seven additional dependency relations under the unspecified dep relation (dep:infl, dep:aux, etc.). in both cases the authors strive to create a more comprehensive representation of a polysynthetic language in ud, but the resulting annotation is not consistent with some of the ud principles. the ud approach assumes that the basic units are words @xcite , therefore, to achieve greater consistency, even in polysynthetic languages the word-based analysis should be favored over the morpheme-based analysis. in addition, we believe that such radical adjustments to ud as proposed for yupik @xcite may be justified for one specific language (or one specific family) but generalization of this approach to all polysynthetic languages can be avoided. in this paper, we introduce a new way of dealing with polysynthetic morphology in ud and show that our approach aligns well with the ud framework. specifically, we discuss the annotation of the treebank of abaza, a polysynthetic northwest caucasian language. the polysynthetic nature of abaza manifests itself mostly in verbal morphology. abaza has a rich system of prefixes that are used for crossreferencing up to four verbal arguments. these prefixes indicate the number, person, gender, and grammatical role of each argument. as shown in in addition to cross-referencing prefixes, there are more than a dozen types of affixes that can be attached to the verbal form. these include temporal markers, voice markers, markers of negation, locative affixes, etc. the ordering of those affixes is shown in although the basic word order is sov, some variation is allowed. for instance, there are cases of arguments appearing in the postverbal position. in example (1), the absolutive subject a-waʕá (defpeople) occurs in the rightmost position in the clause. 2 (1) abar-awəj emp-dist a-pš-ta 3sg.n.io-similar-adv j-bzaza-kʷa-d 3pl.abs-live-pl-dcl a-waʕa def-people 'thus lived the people.' ## spoken corpus of abaza the treebank presented in this paper is based on data from the spoken corpus of abaza. 3 this corpus was built using the tsacorpus platform (see @xcite for a brief description of the platform). it contains 25 spoken texts recorded from 8 different speakers. the recordings were made in the village of inžič-čukun in the karachay-cherkess republic, russia, between 2017 and 2019. the total duration of recorded data is approximately one hour. the texts contained in the spoken corpus of abaza were initially transcribed using the abaza orthography. further, these transcriptions were converted into an ipa-based transcription. the participants of the abaza research group provided interlinear glosses for each text based on the translations obtained from the speakers of abaza. the texts were annotated using the elan software @xcite , therefore each sentences is aligned with a corresponding audio segment. ## preprocessing we devised a specific pipeline to convert elan files into ten-column conll-u format. we started by extracting the glossing abbreviations from the interlinear annotations. as the corpus uses an idiosyncratic notation for glosses, we have created a mapping between the interlinear glosses from the corpus and the corresponding morphological features compatible with the conll-u format. we then used the script foot_3 written by francis tyers to convert the cleaned sets of abaza morphological features into ud morphological features using our mapping. the untransformed glosses were also preserved to be included in the misc section of the conll-u format. as the final step, we manually added lemmas to each wordform in the conll-u annotations. we choose to use the original cyrillic-based orthography instead of the phonological transcription in our treebank for the following reason. the abaza orthography is used in non-annotated texts available online: newspapers and works of fiction. since we plan to train an automatic parsing model to annotate more data for this treebank, the model needs to be trained on the data which has the same orthography as in the texts that it will be used to annotate. ## morphology many of the categories expressed by affixes in abaza cannot be easily converted to ud annotation. first, verbal forms often have locative prefixes, which specify the meaning of the root. for example, in (2) the verbal root on its own means 'to fly', but with the addition of the locative prefix tә-'out', its meaning changes to 'fly away.' one way of dealing with this kind of morphology consists in treating all affixes as independent lexical items, as was suggested for st. lawrence island yupik @xcite , but this goes against the lexicalist approach adopted in the ud framework. here we want to propose an alternative solution for the abaza treebank. we suggest to keep the information about the meaning of each morpheme in the misc section of conll-u format. that way, it can still be available to the researchers that want to examine our data. at the same time, in the feat section we retain only those morphological features that are relevant to syntactic structure. specifically, we decided to limit the grammatical features of abaza encoded in ud to argument cross-referencing, valencychanging operations (reflexive, causative), finiteness, tense, mood, interrogativity and polarity. for example, compare the sentence (4) and its annotation in conll-u format in figure 1 . example (4) contains two verbal forms -dә-rš'ә-n 'they killed him' and d-sә-z-qa-r-g-χ-t ̣ 'they brought him to me'. both verbs have crossreferencing markers which allow to identify syntactic relations between the predicates and their arguments. final suffixes on verbal forms cumulatively express tense, mood and finiteness, and they are crucial for understanding the syntactic status of the predicate in the clause. the rest of the information present in the glosses of verbal forms -the cislocative prefix and the repetitive suffix -is not included in the feat section of the annotation because it is not relevant to syntax. ## syntax in this paper, we propose to constrain the morphosyntactic information to the level of the morphological annotation so that the syntactic annotation does not differ from other languages present in ud. overall, we were only required to add one language-specific relation (dep:repeat) and resolve minor complications with several expressions.