A purinã U niversal D ependencies Treebank (2021)

Abstract: This paper presents and discusses the first Universal Dependencies treebank for the Apurinã language. The treebank contains 76 fully annotated sentences, applies 14 parts-of-speech, as well as seven augmented or new features — some of which are unique to Apurinã. The construction of the treebank has also served as an opportunity to develop finite-state description of the language and facilitate the transfer of open-source infrastructure possibilities to an endangered language of the Amazon. The source materials used in the initial treebank represent fieldwork practices where not all tokens of all sentences are equally annotated. For this reason, establishing regular annotation practices for the entire Apurinã treebank is an ongoing project.

## introduction apurinã (iso code apu) is an endangered language spoken in the amazon basin. the language has around 2,000 native speakers and it is definitely endangered according to the unesco classification @xcite . this paper is dedicated to describing the first ever universal dependencies (ud) treebank for apurinã foot_0 . we describe how the treebank was created, and what exact decisions were made in different parts of the process. the ud project @xcite has the goal of collecting syntactically annotated corpora containing information about lemmas, parts-of-speech, morphology and dependencies in such a fashion that the annotation conventions are shared across languages, although there may be inconsistencies between languages (see @xcite . as the number of south american languages represented in the universal dependencies project has grown rapidly in the last years (see i.e. @xcite , the descriptions of individual treebanks are thereby also a very valuable resource that helps to maintain consistency in the treebanks of this complex linguistic regions. the advantage of ud treebanks is that they can be used directly in many neural nlp applications such as parsers @xcite and part-of-speech taggers @xcite . although the endangered languages have a very different starting point in comparison with large languages @xcite , there has been recent work @xcite @xcite showcasing good results on a variety of tasks even for the few endangered languages that have a ud treebank. the fact that ud treebanks can be used with neural models to build higher level nlp tools is one of the key motivations for us to build this resource for apurinã. in addition to nlp research, ud treebanks have been used in many purely linguistically motivated research papers @xcite @xcite . we believe such developments will only grow stronger, and believe that easily available treebanks in the ud project, covering continuously better the world's linguistic diversity, will continue widening their role as suitable and valuable tools for both descriptive linguistic research and computational linguistics. this goal will be achievable only by creating an open discussion about the conventions and choices done in different treebanks, which can be adjusted and refined at the later stage. this study aims to provide such description about apurinã treebank. an example of a ud annotated sentence in apurinã can be seen in figure 1 . ## modelling the apurinã language in ud the apurinã language has a rich morphology with regular correlation between numerous formatives and semantic categories. one challenge in the conversion from fieldwork/typology style annotation to that used in the ud project is to choose what features should or can be highlighted with specific transferability to other ud projects and which ones should only be represented as language specific morphology. the task has also been contemplated from a finite-state perspective, where regular inflection plays a decisive role in determining lemma and regular inflection strategies. finite-state description also entails the use of the open-source giellalt infrastructure (norwegian arctic university, tromsø) @xcite , which introduces a large number of mutual tag definitions and practices that can be applied to apurinã with ample analogy from the morphologically challenging uralic and other languages of the circum-polar region. solutions for dealing with the categories of case, number, person and gender are available in the giellalt infrastructure. extensions, however, have been required for apurinã in the categories of number, person and gender. unlike some indo-european and uralic languages, the category of gender must also be applied to the subjects and objects of verbs; subject and object marking for number (see facundes et al. 2021) and person categories could have been adapted directly from description work in the erzya @xcite and moksha (rueter, 2018) ud treebanks. ## treebanks in figures there were 76 valid and dependency-annotated sentences in the first release. broken into figures, these sentences contain 574 tokens and a 454 word count, which can be further broken down into features, parts-of-speech and dependency relations. the most salient features are case (101), gender (96), number (73), but the newly introduced gender[obj] (47) is also well attested. the case feature owes its prominence to the presence of all nouns not marked for oblique cases, i.e. nom; this leaves a total of 25 obliques (see ## future work due to the size and orientation of the dataset some features of the apurinã language have been neglected. it will also be a challenge to apply recent studies in noun incorporation annotation for ud in @xcite to what facundes and freitas, 2015 describe for apurinã noun and classifier incorporation. another obvious goal for further work is to make apurinã treebank so large that it can be split into train, test and dev portions. the goal to expand the treebank is connected to the availability of resources. currently the sentences used in the treebank come mainly from the grammatical descriptions. as a language documentation corpus exists foot_1 , an important consideration is whether the treebank sentences could be more closely connected to audio and video recordings as well, and, of course, the main corpora in belém, as multimodal resources are valuable in language documentation.