Annotating Verbal MWE s in I rish for the PARSEME Shared Task 1.2 (2020)

Abstract: This paper describes the creation of two Irish corpora (labelled and unlabelled) for verbal MWEs for inclusion in the PARSEME Shared Task 1.2 on automatic identification of verbal MWEs, and the process of developing verbal MWE categories for Irish. A qualitative analysis on the two corpora is presented, along with discussion of Irish verbal MWEs.

## introduction multiword expressions (mwes) present a well-documented challenge in the field of nlp, given that they appear in a variety of forms, are idiosyncratic in nature, and prevalent in our lexicon @xcite @xcite . that said, their correct handling can aid in a number of nlp tasks, including word-sense disambiguation, parsing, and machine translation @xcite . this has given rise to a number of working groups dedicated to identifying and interpreting mwes. parseme is one such group, with the aim of improving cross-lingual processing of mwes. their shared task on the automatic identification of verbal mwes @xcite is now in its third iteration, and their guidelines have expanded to include 27 languages. this year saw the addition of irish, as the first of the celtic languages to participate. two corpora of irish text were created for this shared task: a small corpus consisting of manually labelled verbal mwes (vmwes), and a much larger corpus for use in unsupervised vmwe identification. research on mwes in irish is still sparse, and much work remains to define the types of mwes that exist. most of the literature on irish linguistics and syntax focuses on a theoretical analysis of the language, and any discussion of idiomatic constructions, which are frequently exceptional cases, tends to be brief. @xcite @xcite . some studies offer more in-depth analysis on particular types of mwes, such as light-verb constructions @xcite , the idiomatic use of prepositions with verbs @xcite and idioms @xcite . others have offered a preliminary categorisation of irish mwes @xcite . the categorisation carried out in our previous work @xcite is largely based on the annotation guidelines developed for the parseme shared tasks foot_0 , and as such can be used as a starting point for the development of a comprehensive set of vmwe categories for irish. ## verbal mwe categories in irish given that the focus of parseme is on the identification of verbal mwes, some categories of mwes considered in our previous work, such as nominal compounds or fixed expressions, are excluded. the categories examined here include two universal categories (verbal idioms and light verb constructions) that are found in all participating languages of the parseme shared task: two quasi-universal categories this work is licensed under a creative commons attribution 4.0 international licence. licence details: http:// creativecommons.org/licenses/by/4.0/ . light verb constructions (lvcs) are described in the parseme guidelines as formed by a verb, v, and a (single or compound) noun, n, which either directly depends on v or is introduced by a preposition. constructions where v's syntactic subject is n's semantic argument are full lvcs and annotated as lvc.full, while constructions where the subject of v is the cause or source of the event or state expressed by n are annotated as lvc.cause. examples include the lvc.full déan dearmad (do negligence) 'forget' and the lvc.cause cuir áthas (put joy) 'make happy'. verb particle constructions (vpcs) -sometimes called phrasal verbs -consist of a verb, and a dependent intransitive particle (usually a directional adverb in irish), where the particle causes a significant shift in meaning in the verb. this change in meaning can be either fully non-compositional (annotated as vpc.full, e.g. tabhair amach (give out) 'scold') or semi-compositional (annotated as vpc.semi, e.g. glan suas (clean up) 'clean up'). inherently adpositional verbs (iavs) are considered an experimental category in the parseme guidelines and language teams may optionally annotate for this category as a final step in the annotation process. the construction consists of a verb and a dependent prepositional phrase, where the preposition is considered integral to the construction, i.e. "it cannot be omitted without markedly altering the meaning of the verb". this construction occurs frequently in irish (e.g. buail le (hit with) 'meet'), and as such it was decided to annotate this category in the current edition, to determine whether future versions of the corpus should contain this category. vmwes can themselves form part of the iav construction, as in the iav cuir suas le (put up with) 'put up with', which contains the vpc cuir suas (put up) 'put up', which is why this category must be annotated last. verbal idioms (vids) are idiomatic constructions with at least two lexicalised parts, including a head and at least one dependent. these dependents can be of several different categories (e.g. tar an crú ar an tairne (come the shoe on the nail) 'come to the test', ag siúl le chéile (at walking with each-other) 'courting'). also included in vids are sentential expressions with no open slots, such as proverbs (e.g. ní neart go cur le chéile (is-not strength without put with each-other) 'there's strength in unity'). ## creation of corpora previous editions of the shared task were focused on supervised training of mwe identification, through a manually annotated corpus of vmwes that was also annotated for pos information, morphological tags, and dependency trees. this edition, however, included a corpus for unsupervised training, which contained no vmwe information, but was automatically tokenised, lemmatised and parsed using ud-pipe @xcite . 3 ## conclusion this paper describes an initial attempt at the manual annotation of irish verbal mwes, including developing a categorisation scheme that aligns with the parseme annotation guidelines. it was found that seven of the categories were applicable to irish language, and the experimental category of iav occurred frequently. the results of this annotation are explored, along with results from participating systems in the shared task. it appears that the submitted systems found the task of automatic identification particularly difficult for irish; this is likely due to the small size of the corpus and number of vmwes annotated, the high rate of unseen vmwes in the test data when compared to other languages, and the relatively large number of potential categories that increases the complexity of the task. in the future we plan to continue the work of manual annotation of these vmwes, particularly in defining the categories more precisely, refining the irish-specific guidelines and adding language-specific tests for certain categories such as vpcs, and expanding the size of the corpus.