Methodological issues regarding the semi-automatic UD treebank creation of under-resourced languages: the case of Pomak (2023)

Abstract: Pomak is an endangered oral Slavic language of Thrace/Greece. We present a short description of its interesting morphological and syntactic features in the UD framework. Because the morphological annotation of the treebank takes advantage of existing resources, it requires a different methodological approach from the one adopted for syntactic annotation that has started from scratch. It also requires the option of obtaining morphological predictions/evaluation separately from the syntactic ones with state-of-the-art NLP tools. Active annotation is applied in various settings in order to identify the best model that would facilitate the ongoing syntactic annotation.

## introduction the development of the pomak ud (universal dependencies) treebank was carried out as a case study of the project philotis, which aims at providing the infrastructure for the multimodal documentation of living languages. 1 pomak is an endangered oral slavic language of historical thrace (south balkans). morphological and syntactic annotation are carried out in two distinct settings because the first one uses existing resources and the second one starts from scratch. sections 2 and 3 briefly present the current situation of pomak language, the script/orthography adopted for the development of its treebank and the available resources. in section 4 a short linguistic description of pomak is given in the ud framework. the annotation procedure is discussed in section 5. conclusions and future plans are presented in section 6. ## about pomak pomak (endonym: pomácky, pomácko, pomácku or other dialectal variants) is a non-standardised 1 https://philotis.athenarc.gr/ east south slavic language variety. 2 pomak is spoken in bulgaria and greece (mainly in the rhodope mountain area), in the european part of turkey and in places of pomak diaspora @xcite . the pomak dialect continuum has been influenced by greek and turkish due to extensive bilingualism or trilingualism @xcite . pomak scores low on all six factors of language vitality and endangerment proposed by unesco (for more details see @xcite . in short, there is little written legacy of merely symbolic significance for the speakers of pomak, the language is not taught at school, it is mainly used in family settings, which are increasingly penetrated by the dominant language(s) @xcite . furthermore, pomak showcases certain issues involved in the development of nlp resources for an oral, non-standardised language with some legacy such as texts and/or lexica of some type; this is the case for a number of, european at least, language varieties @xcite . the exploitation of the linguistic knowledge contained in such legacy may require (i) the transcription/transformation of the textual sources to the right processable format (ii) some adaptation of the processing pipelines offered by open-source state-of-the-art nlp tools. both types of action were required for the development of the pomak ud treebank. ## pomak textual sources and scripts there are sporadic transcriptions and recordings of pomak folk songs and tales as well as very few modern texts (mostly journalistic texts and translations from greek and english into pomak). the existing texts are written in a variety of scripts, ranging from bulgarian-based cyrillic to modern greek to an english-based latin alphabet. philo-tis collected these scattered resources through a network of native speakers and greek scholars who, for various reasons, are close to the pomak community. selected parts of this material are included in a corpus of about 130,000 words. the corpus will be made available on the web to institutions and individuals for research and innovation purposes; at the moment, it is available for the same purposes after personal contact with the first and/or last author. where possible, the geographical origin of the texts is also given as a hint to the dialect used in the text. we took advantage of the pomak electronic lexicon rodopsky, which contains about 61.500 lemmas corresponding to about 3.5 x 10 6 unique forms (i.e., combinations of a lexical token and a pos symbol) annotated for lemma, pos and morphological features. 3 rodopsky, the existing textual sources and the fact that pomak is a slavic language have helped us solve several issues regarding pomak orthography, namely identification of words and their grammatical function and the identification of inflectional paradigms. still, a lot of work was required to adapt the linguistic information in rodopsky and the textual legacy of pomak to contemporary linguistics and uds. text homogenisation work was necessary because pomak texts, including rodopsky, employ various orthographies. the latin-based alphabet 3 https://www.rodopsky.gr/ proposed by ritvan karahoǧa and panagiotis g. krimpas (hereinafter: k&k alphabet), which has a language resource-oriented accented version and a non-accented all-purpose version, was used to semi-automatically transliterate rodopsky and the corpus. the k&k alphabet has been developed along the following lines @xcite : (i) portability of the alphabet (use of unicode) (ii) phonetic transparency (iii) easily learned representations of sounds due to the use of similar diacritics for same articulation sounds and the absence of digraphs (iv) consistent spelling not affected by predictable allophony; for instance, the @xcite , g [g] in word-final position or before a voiceless consonant is not shown for the sake of consistency across the declension/conjugation paradigm, which is why hlaeb 'bread (nom|sg)' is spelled with a b although it is actually pronounced [hle5p] in order to ensure consistency across the clitic paradigm hlaebu 'of/to (the) bread', hlaebove 'breads (nom|pl)' etc. (v) the k&k alphabet is based on the dialect of myki but it can also partially serve as a hyperdialectal script by allowing various predictable pronunciations of the same graph according to dialect; for instance, the vowel in the first syllable of zømom '(that) i take,' which is pronounced as @xcite in myki, can also be acceptably pronounced as @xcite in echinos or as @xcite in dimario, no matter that all three variants are spelled with an ø. this is because speakers from echinos and dimario have no [ø]-sound, which is why they spontaneously replace it with @xcite or @xcite , respectively, while speakers from myki, if asked to read out the digraph jo or the graph e would not automatically pronounce them as @xcite , given that they do have words with @xcite in their native variety. however, a hyperdialectal pomak orthography is often not possible, given that some varieties differ also in the lexical and/or morphological level. ## development of the pomak treebank τhe ud pomak treebank is developed in two distinct steps: morphological annotation and syntactic annotation. different methodologies have been adopted for each step because background knowledge about pomak morphology was available (in rodopsky) while the description of pomak syntax is an ongoing process intertwined with the annotation of the pomak corpus with ud syntactic dependencies. naturally, morphological annotation preceded syntactic annotation so the two steps are discussed below in this order. ## discussion and future work we have presented the procedure we adopted to develop a ud treebank of pomak, an endangered oral language of the east south slavic group. the task is a case study of the project philotis and was supported by a group of computational linguists, linguists fluent in slavic languages and pomak and engineers as well as by the pomak community. pomak exploited the ud inventory of labels and exposed unique linguistic phenomena regarding the system of deixis and the verb system; modelling of deixis led to the definition of a new ud morphological feature. in this work we had the opportunity to apply two different annotation methods, one exploiting background knowledge (morphology) and one developing knowledge from scratch. the exploitation of background knowledge led to excellent accuracy scores with minimal annotation effort, however, few languages are endowed with the required resources. therefore, an evaluation of the active annotation method that assumes no previous (morphological and/or syntactic) knowledge may be of more general interest. as the syntactic annotation of pomak is still going on, a better understanding of the method, e.g., its impact on annotation time and costs, is among our immediate plans.