A linguistically-motivated annotation model of modality in E nglish and S panish: Insights from MULTINOT (2016)

Abstract: In this paper we present current work on the design and validation of a linguistically-motivated annotation model of modality in English and Spanish in the context of the MULTINOT project. Our annotation model captures four basic modal meanings and their subtypes, on the one hand, and provides a fine-grained characterisation of the syntactic realisations of those meanings in English and Spanish, on the other. We validate the modal tagset proposed through an agreement study performed on a bilingual sample of four hundred sentences extracted from original texts of the MULTINOT corpus, and discuss the difficult cases encountered in the annotation experiment. We also describe current steps in the implementation of the proposed scheme for the large-scale annotation of the bilingual corpus using both automatic and manual procedures.

## introduction in this paper we describe the construction and empirical validation of a modality annotation scheme for english and spanish in the context of the multinot project, whose main aim is the development of a parallel english-spanish corpus which is balanced -in terms of register diversity and translation directions -and whose design and enrichment with multiple layers of linguistic annotations focuses on quality rather than on quantity (see @xcite 2 2 . one of the most relevant annotation tasks within multinot focuses on the category of modality in english and spanish, not only for its theoretical interest as a topic of contrastive research between these two languages, but also for its computational relevance in the nlp community, where modally-annotated corpora are an indispensable resource for training systems to automatically interpret modality. practical nlp applications such as textual entailment, information extraction, question answering, sentiment analysis and machine translation need to be able to distinguish automatically modal from actual information as part of the complete understanding of a text. in response to this need, the last years have witnessed the development of annotations schemes and annotated corpora for different aspects of modality in different languages @xcite , @xcite , @xcite , @xcite , @xcite , @xcite ). however, the annotation of modal meaning is a complex task, as will be shown in the remainder of this paper. the difficulties derive not only from the practicalities of the annotation process, but also from the subtle distinctions which emerge in the modal domain. in addition, when the task involves more than one language, the complexity increases, given the language-specific features that have to be considered in the annotation process. to our knowledge, there are no annotation schemes for modality which specifically address the commonalities and the language-specific features of english and spanish, although there are various proposals for english and for other languages. the present work tries to fill a gap in this area by approaching the annotation of modality from two interrelated perspectives: (a) the functional/semantic perspective, which captures the commonalities shared between both languages in the creation of modal meanings, and (b) the syntactic perspective, which considers the language-specific preferences in the encoding of similar modal meanings in english and spanish. this approach allows us to discover the form-function correspondences of different modal values in english and spanish, which will be useful not only from a theoretical linguistic perspective, but also for computational applications where language comparison is central, such as machine translation and computer-aided translation. the paper is structured as follows. we first present our theoretical background and discuss some related work (section 2). we then outline some basic decisions which have guided our annotation proposal (section 3). in section 4 we present the common functional/semantic tagset proposed, which captures four basic modal meanings and their subtypes in both english and spanish, namely, epistemic/evidential, deontic, dynamic and volitional, and describe each of these meanings in subsections 4.1, 4.2, 4.3 and 4.4., respectively. in section 5 we describe the latest in a series of annotation experiments to validate the proposed tagset (5.1), report on the results obtained through several interannotator agreement studies (5.2) and discuss the difficult cases (5.3). section 6 presents the language-specific tagsets for each of the modal meanings proposed and section 7 focuses on the implementation of the annotation scheme using the uam corpus tool. finally, section 8 summarises the work and concludes with some pointers for the future. ## theoretical background and related work in the linguistics community there is an extensive body of research on english modality which has focused on the conceptualisation of this broad category in terms of a number of meanings, the most common labels being 'epistemic @xcite @xcite . in addition, some scholars have also included 'boulomaic' or 'volitional' modality to capture meanings concerned with willingness, intention or wish. while the first three macro-categories @xcite constitute what is known as 'core modality', the last one is considered by some scholars as 'peripheral'. we share nuyts' @xcite viewpoint that the main reason for this different consideration lies in the historical predominance of form-oriented studies in the literature on modality, with many references concentrating on the modal auxiliaries. as will be seen in the remainder of the article, 'epistemic', 'deontic' and 'dynamic' modality can be expressed by all the modal auxiliaries in english and by several periphrases in spanish, while 'volitional' modality is mainly realised by other expressions. in english, the only modal auxiliaries that can express volitional modality are will and would, and in spanish its most grammaticalised realisation is the future tense, followed by the construction querer + infinitive. however, notional approaches to modality based on meaning rather than form have increased in the last two decades, with the consequence that volitional modality is increasingly considered as a modality on a par with the others: for example, @xcite advocates for a category of 'boulomaic attitude', and @xcite includes a 'bouletic' modality. moreover, volitional modality shares a number of features with the other modalities: for example, it conveys an attitude of the addresser (speaker or writer) towards what is communicated @xcite . for these reasons, we consider volitional modality as a modal category, together with the epistemic, deontic and dynamic. the four basic modalities can be briefly characterised as follows: markets must function, devices must function, networks must function and investment needs to happen. (eo-speech-012) (4) population growth is therefore not a reason against giving overseas aid, although it should make us think about the kind of aid to give. (eo-essay-010) (5) "i'm here simply to listen. you can tell me anything. that's what i'm for." (eo-fiction-011) (6) you must not modify the paper or digital copies of any materials you have printed off or downloaded in any way (eo-webp-007) volitional modality covers as a scale of degrees of wish, its middle point being acceptance @xcite ). examples ( 9 ) and (10) express willingness and acceptance, respectively: as to the literature on practical corpus annotation of modality, previous research has targeted mostly english texts, and most of the work has focused on modal auxiliaries and verbs, and on the distinction between factual (actual) and non-factual (modal) information, since this is necessary for a number of nlp tasks such as textual entailment @xcite @xcite , information extraction @xcite , question answering @xcite , sentiment analysis @xcite , and machine translation @xcite . given the need for high-quality annotated datasets with modal features, projects on other languages have also been developed during the last years (see @xcite @xcite @xcite . also, previous work by the authors of this paper has focused on the annotation of specific linguistic expressions in english and spanish (i.e. modal verbs and certain adverbs), with the aim of distinguishing modal and non-modal realisations of each of the expressions, as well as the more theoretical aim of setting forth the subsequent implications for determining the concept and scope of modality (see @xcite @xcite . however, a concrete proposal for the annotation of modality in spanish as a functional category with characteristic realisational features does not yet exist, and, to our knowledge, there are no practical annotation schemes which consider the annotation of english and spanish bilingual texts. 4 an interesting proposal was put forward by @xcite . these authors propose a cross-linguistic annotation model of modality which works with two layers: a functional layer, which allows them to use the same modal categories across languages, and a linguistic layer, which captures the syntactic nature of the modal triggers. our own proposal is similar to theirs in proposing two distinct layers of annotation to capture both the functional/semantic commonalities between english and spanish and the language-specific syntagmatic realisations. however, it differs in several respects: first, it is more fine-grained in terms of the modal meanings included in our annotation scheme; second, we do not include the notion of factuality in our annotation model since this is a separate dimension which cuts across the four basic modal meanings but does not serve to establish distinctions between them. third, we propose a more concrete and linguistically-sophisticated specification of the syntagmatic options available to english and spanish for the expression of modal meanings. for this task we have used two main sources of inspiration: a) the syntagmatic options proposed by m.a.k halliday in his systemic-functional account of modality and modulation in english @xcite ; and b) the contrastive account of modality in english and spanish proposed in @xcite ). as will be shown in section 5 below, the resulting specification offers a fully-fledged lexicogrammatical cartography of the syntagmatic realisations of the different modal meanings proposed for english and spanish, which will hopefully result in a much more complete characterisation of these two languages in terms of modal features. ## annotation proposal: basic decisions as pointed out in the introduction above, the annotation of modality is not an easy task. from a purely theoretical point of view, there are a number of problems which have to be considered when dealing with this category. first, modality itself is not a unified notion, and there are different interpretations as to what counts as 'modal' among linguists, probably because originally it was approached from form to meaning, i.e., focusing on modal verbs and their meanings. second, linguists do not agree in the number and types of modal meanings to be defined or in the meanings that are covered under certain modality types. a further complication is that that there is often no clear-cut distinction between modal and other meanings, thus creating a continuum of expressions that range from clearly modal to marginally modal. for example, the notion of willingness -one central meaning of volitional modality -is connected with the notions of liking, availability, readiness, and ability, which is also one of the central meanings of dynamic modality. third, semantics and pragmatics are closely intertwined in the expression of modal meanings, and it is often possible to find a literal modal interpretation and a pragmatic modal interpretation. for example, the meaning of absence of obligation (you don't need to) can be used pragmatically to prohibit (you don't need to tell him), when said instead of you mustn't tell him). finally, the relationship between negation and modal meanings is a complex one. with some modal expressions, negation does not fundamentally alter the quality of the modality being expressed. thus, the negation of tendency is still tendency (he tends to... / he doesn't tend to...); likewise, the negation of epistemic possibility is still epistemic possibility (perhaps she is... / perhaps she is not...). however, when we negate obligation we can obtain two different results: either prohibition (you must do it / you mustn't do it) or the mere absence of obligation, which is a completely different type of meaning (you must do it / you don't need to do it). similarly, when we negate an expression that intrinsically indicates negative willingness (i don't object to ...), the result is a different modal meaning: acceptance. in view of the problems described above, our annotation model is based on the following assumptions: in the following sections we define and describe in detail the tagsets that we propose for the annotation of modality in english and spanish. we first present the functional semantic tagset consisting of four basic modal meanings and their subtypes (section 4). this is followed by a description of the last in a sequence of annotation experiments carried out on a bilingual sample of sentences extracted from the multinot corpus (section 5), including the description of the annotated datasets (5.1), the annotation results (5.2), and the difficult cases (5.3). finally, we present the syntactic tagset which has been elaborated and refined on the basis of the different annotation experiments (section 6). ## annotation tagset for modal meanings in english and spanish for the annotation of modal meanings in english and spanish we first designed a core tagset consisting of four basic types of modal meanings, and an extended tagset capturing the different subtypes. the groupings and the subtypes presented below in fig. 1 below are the result of a number of preliminary annotation experiments during which we elaborated and refined the tags until we reached a consensus with respect to the basic and the secondary meanings. as shown in fig. 1 , the tagsets are hierarchical, allowing the annotator to choose the coarser tags from the core tagset (ep, de, dy, vo), when in doubt about the more fine-grained subtypes from the extended tagset. for example, if s/he is uncertain about whether a markable is 'possibility' or 'probability', s/he can simply tag it as 'epistemic' [ep] and 'non-evidential' @xcite . the abbreviated form of each tag is given in capital letters in brackets next to the full form. each of these modal meanings and their associated tags are described in detail in the following subsections and illustrated with examples extracted from the multinot corpus. ## conclusion and future work in this paper we have reported on current work on the design, validation, and implementation of a linguistically-motivated annotation model of modality in english and spanish in the framework of the multinot project. in this project, aimed at the creation of a richlyannotated bilingual english-spanish corpus consisting of original and translated texts, the annotation of modal values and their realisations is an important task, not only from a contrastive and translational point of view, but also for its computational relevance in the nlp community, where modally-annotated corpora are an indispensable resource for training systems to automatically interpret modality. in order to capture not only the modal meanings which are common between english and spanish, but also their language-specific realisations in both languages, we have designed an annotation model consisting of two interrelated tagsets: a functional-semantic tagset, capturing four basic modal meanings and their subtypes, and a languagespecific tagset, providing a fine-grained characterisation of the syntactic realisations of those meanings in english and spanish. the proposed functional-semantic tagset is the result of various rounds of annotation experiments to refine and validate its reliability for the large-scale annotation of english and spanish texts. in the paper we describe the latest experiment carried on a bilingual sample dataset from the multinot corpus, where we found high interannotator agreement rates for both the coarser functional-semantic tags as well as for the more specific subtypes. these results indicate that the proposed tags are reliable, though some problems and difficult cases were encountered during the annotation process. these can be grouped into two main types: a) cases where there was a degree of overlap in the modal meanings expressed by the triggers, such as modal auxiliaries (can, may, might, must, etc.) in english and their spanish counterparts; b) cases where annotators disagree on the modal nature of the triggers. this group includes mostly lexical verbs, adjectives and nouns such as 'prohibit', 'necessary' or 'obligation' which have a meaning that that belongs to one of the modality august 2016 types. in the paper we discuss each of these cases in detail and indicate possible ways to solve ambiguities when confronted with them in the annotation process. current work is focused on the implementation of the proposed scheme for the large-scale annotation of the bilingual texts of the multinot corpus using both automatic and manual procedures, as described in the last section of the paper. given the register diversity of multinot corpus and the fact that it includes both original and translated texts, it is expected that the modal annotations to be carried out in the upcoming months will be a useful resource for both the linguistic and the nlp communities.