A UD Treebank for Bohairic C optic (2025)

Abstract: Despite recent advances in digital resources for other Coptic dialects, especially Sahidic, Bohairic Coptic, the main Coptic dialect for pre-Mamluk, late Byzantine Egypt, and the contemporary language of the Coptic Church, remains critically under-resourced. This paper presents and evaluates the first syntactically annotated corpus of Bohairic Coptic, sampling data from a range of works, including Biblical text, saints’ lives and Christian ascetic writing. We also explore some of the main differences we observe compared to the existing UD treebank of Sahidic Coptic, the classical dialect of the language, and conduct joint and cross-dialect parsing experiments, revealing the unique nature of Bohairic as a related, but distinct variety from the more often studied Sahidic.

## introduction 1.coptic coptic was the indigenous spoken and written language of egypt during the late roman, byzantine, and early islamic periods. as the final stage of the ancient egyptian branch of the afro-asiatic language family, coptic concludes a linguistic tradition with the longest continuous written record in human history, which includes three millennia of hieroglyphic, hieratic and demotic egyptian writing, as well as over a millennium of writing in coptic itself, a form of the same language written mainly in greek letters. initially a very low resource language, recent efforts to digitize and annotate data for coptic have resulted in now substantial resources for sahidic coptic, the classical dialect of the language, with corpora @xcite , a machine readable dictionary @xcite and a ud dependency treebank @xcite . at the same time, other forms of coptic, namely dialects beyond sahidic, continue to have little or no annotated resources. in this paper, we aim to address this gap by introducing a ud treebank for a second, very significant dialect of the language: bohairic coptic. in this section we offer a brief summary of coptic and its dialects, highlighting especially some of the main differences between the classical sahidic, and bohairic coptic, which we explore in more detail later on using our data. geographic diversity in late ancient egypt resulted in a range of regional dialects rather than one standardized form of coptic. scholars identify six principal dialects, but two of these, sahidic and bohairic, were the most influential @xcite . sahidic dominated as the literary language from the third to the ninth century ce before being gradually replaced by bohairic, a northern variety that continues to serve today as a heritage and liturgical language among coptic communities in egypt and the diaspora. despite the diversity of surviving evidence for coptic dialects, print and digital resources for the language have remained limited and have focused almost exclusively on sahidic. the textual evidence for the dialect of bohairic, though sizeable (and primarily literary), is accessible mostly in facsimiles (see figure 1 for a papyrus manuscript example) or in older print publications, and many works remain unpublished @xcite . using terms from @xcite , bohairic is at rank 0 of the language technology hierarchy, a 'left-behind' language. ## previous work the bohairic ud treebank joins a growing body of typologically diverse languages analyzed using the ud framework @xcite , in-cluding recent treebanks of related afro-asiatic languages such as biblical and modern hebrew @xcite , @xcite , and very recently, ancient egyptian (díaz hernández and carlo passarotti, 2024), resources we consider in the development of comparable annotation guidelines (and to a lesser extent, treebanks converted to ud, e.g. for hausa, @xcite . the most important previous resource we model our work on is the existing ud treebank for sahidic coptic (zeldes and abrams, 2018), which contains around 60k words from a range of works in a number of genres. in particular, the sahidic treebank contains some biblical material which is in part also available in bohairic (see section 3 below). by selecting the same biblical books and chapters where possible, we are able to conduct some direct comparisons between the dialects which only target parallel passages (see section 4). at the same time, for texts in the sahidic treebank that are unavailable in bohairic, we select substitutes from similar genres, offering a similar range of language usage. in terms of annotation scheme, we closely follow and adapt to bohairic the coptic scriptorium guidelines for annotating parts of speech, lemmatization, sentence splitting and ud dependency relations. in a recent paper, crellin (2025) criticizes the choice of ud as a treebanking framework, among other languages for coptic, as unmotivated, stating "no overt discussion of the rationale for choosing [...] universal dependencies" could be found @xcite . we would therefore like to explicitly motivate the choice of ud for the bohairic treebank beyond the obvious benefit of comparability with other resources (see section 4), and outline some of the key decisions in treebanking coptic. the most crucial decision we follow is treatment of lexical verbs as heads of their clauses, despite their etymology in many tenses in earlier egyptian as subordinated, nominalized infinitives. for example, the verb "hear" in (5) is the only possible head for the clause, which otherwise contains only the subject. meanwhile in (6), the past auxiliary 'a' in 'a-f-sōtem' would have been analyzed as the head in earlier late egyptian, as the construction is derived from a periphrasis, late egyptian @xmath0, lit. "did-he hear", or more freely, "he did hearing". we motivate the choice of the lexical verb as the head by the basic ud principle of lexico-centrism, which also provides a more parallel analysis for subjects in the durative and past tenses shown above. since coptic, synchronically an agglutinative language, has a broad range of tenses and constructions, but only a handful of etymological sources for agglutinative morphemes (almost always forms of the late egyptian verbs for "do", "give" or "know"), choosing a non-lexico-centric scheme would result in an analysis in which coptic has only a handful of distinct verbs. the choice of ud is therefore quite conscious, and especially given the benefits of comparability, without obvious superior alternatives. we also match our native coptic part of speech tagging scheme and its mapping to universal pos tags to those used in the sahidic treebank, as well as using multiword tokens (mwts) to represent bound groups in the conllu format (i.e. examples (5) and ( 6 ) would be one mwt each, containing two and three word forms respectively). ## data the textual data in the bohairic ud corpus consists of selections from works in multiple genres. we include selections from hagiography (saints' lives) of two prominent figures in early christian egypt: shenoute, the leader of a federation of male and female monasteries in the fourth-fifth centuries; and isaac, patriarch (or coptic pope) of alexandria from 686 to 689 ce. the life of shenoute is a compilation of panegyric works about shenoute written in bohairic coptic over decades after his death and compiled into the genre of a saint's life (see @xcite . the life of isaac is a saint's life written in bohairic coptic possibly in the seventh century after isaac's death, focusing mostly on his adult life as a monk, priest, and patriarch during the early islamic period @xcite . the lausiac history is a narrative text originally written in greek consisting of anecdotes about fourth-century monks and so has hagiographical elements as well as generic elements from travel narratives @xcite the text of each of these works is derived from previous digital or print editions. the life of shenoute comes from a digital edition created by hany takla of the st. shenouda the archimandrite coptic society, based primarily on the edition published by @xcite . dr. lydia bremer-mccollum of the coptic scriptorium project foot_1 extracted digitized text using optical character recognition (ocr) from the public domain edition of the life of isaac and the public domain edition of the bohairic lausiac history, both edited by amélineau (1887, 1890), followed by manual correction of ocr errors. the gospel of mark and 1 corinthians digital texts come from the marcion project; foot_2 both ultimately derive from the print edition of @xcite . the text of habakkuk is from the working digital edition in-progress created by the göttingen coptic old testament project. 4 all of the digital versions were processed by the coptic scriptorium project's natural language processing tools (zeldes and schroeder, 2016), which have normalized the text, including normalizing variant spellings and expanding any abbreviations; for this paper, all nlp processing has been manually checked by one or more of the authors before treebanking. ## comparing ud bohairic and sahidic like other projects adding ud treebanks in lowresource languages for which closely related languages already have treebanks @xcite , one of our goals is to explore the ways in which bohairic diverges from other varieties of coptic -ideally, we would like to have treebanks of all coptic dialects, but for the present we must focus on the comparison with sahidic. dialects and closely related languages can differ in two different ways: they can have categorically distinct constructions, such as different auxiliaries, distinct argument structures for equivalent verbs etc., or they can use similar constructions but in quantitatively different usage patterns. while categorical differences between bohairic coptic and the better studied sahidic are relatively well understood, quantitative differences are more elusive, but can show up in a corpus analysis. on the lexical level, we can note that of the approximately 2,800 unique words attested in the sahidic treebank, and around 2100 unique words in the bohairic treebank, only about 600 are shared, and even among these, identical forms do not always translate to identical meanings. for example while et: 'et-' can be a form of the relative marker in both sahidic and bohairic, it can also represent the precursive form meaning 'after' in bohairic. among the disjoint, dialect-specific vocabulary, many words have corresponding words in the other dialect which differ only due to pronunciation, but some words are totally unique, such as baki 'baki', which means 'town' in bohairic, but does not exist in sahidic. on the syntactic level, we cannot find differences and commonalities as easily, but thanks to the existence of ud trees in both dialects, we can still leverage annotated data in a straightforward way. to find some of the clearest differences that our data reveals, we extract relative proportions of the dependency relations attested in the bohairic and sahidic coptic treebanks, an excerpt of which is presented in as the table shows, striking differences are present for example in the frequencies of dislocated arguments (much more common in bohairic) and iobj (indirect objects, much more common in sahidic). we also note that some control labels, which we would expect to align across datasets, are quite comparable, such as cop for cop- ## conclusion in this paper we presented the first morphosyntactically annotated corpus of bohairic coptic, containing over 30k word forms from a range of texts. by adopting the same guidelines as the existing ud sahidic coptic treebank, we have been able to perform some first studies of more subtle quantitative differences between the dialects, complementing the better known categorical differences between them. we also ran parsing experiments which indicated that models trained on both dialects jointly were able to boost performance on the lower resource bohairic dialect, but not on sahidic. we are hopeful that this corpus will represent a starting point for further expansion of annotated data for bohairic coptic in particular, and coptic dialects in general. we are confident there is much room for both improving nlp tools for coptic using such data, and for studying coptic dialects individually and comparatively.