Subcategorizing Adverbials in U niversal C onceptual C ognitive A nnotation (2021)

Abstract: Universal Conceptual Cognitive Annotation (UCCA) is a semantic annotation scheme that organizes texts into coarse predicate-argument structure, offering broad coverage of semantic phenomena. At the same time, there is still need for a finer-grained treatment of many of the categories. The Adverbial category is of special interest, as it covers a wide range of fundamentally different meanings such as negation, causation, aspect, and event quantification. In this paper we introduce a refinement annotation scheme for UCCA’s Adverbial category, showing that UCCA Adverbials can indeed be subcategorized into at least 7 semantic types, and doing so can help clarify and disambiguate the otherwise coarse-grained labels. We provide a preliminary set of annotation guidelines, as well as pilot annotation experiments with high inter-annotator agreement, confirming the validity of the scheme.

## introduction the ucca representation scheme is designed to be a multi-layered, cross-linguistically portable and stable semantic annotation scheme based on linguistic typology @xcite . among its 14 coarse-grained semantic categories, adverbial serves as the label for modifiers to a scene's main predicate. despite the syntactic-sounding name, adverbial is a semantic category that cuts across a range of syntactic constructions that provide scene-modifying meanings. these meanings fall into drastically different semantic categories-negations, manner pps, modals, adverbs are all candidates for the adverbial category-that change the sentence's meaning in different ways. this paper proposes to refine ucca adverbials, in order to better understand the semantic functions they encode. by distinguishing different adverbial functions, we can disambiguate sentences that are otherwise annotated similarly (if not identically) in ucca. for example: ## background adverbs. it is important to differentiate the semantic adverbial category from the morphosyntactic class of adverbs @xcite . in ucca, for example, the current adverbial (d) material ranges from manner adverbs and expressions of negation to comparatives to semi-contentful light verbs @xcite . ucca categories. the annotation of the ucca scheme is organized into layers. in the foundational layer, each passage is broken down into scenes, which in turn are made up of scene evokers labeled either state (s) or process (p), core argument units called participants (a), which may be either non-scenes (i.e., roughly, 'entities') or scenes themselves, and modifiers such as time (t) or adverbial (d) units @xcite . adverbials can be understood as denoting secondary predications over a scene's main state or process relation. other extensions to ucca. building upon the ucca foundational layer, there have been several efforts and proposals to refine annotations of specific constructions such as implicit arguments @xcite , numeric expressions @xcite , coreference @xcite , and adpositional phrases @xcite . the latter class in particular partially overlaps with the adverbial category, as discussed in §6. this paper will accompany these annotation refinements, with a special focus on the adverbials. ## motivation adverbial category is relatively broad. as mentioned briefly, adverbials represent a wide range of semantic functions; this level of diversity is not shared by other foundational layer categories. consider, for example, the category 'time': it is also a scene-level category, but has a much more specific semantic purpose. the other categories like 'state,' 'process,' and 'participant,' also have better-delimited/dedicated functions, whereas adverbials can target all general non-scene-evoking elements. some adverbials are manner adverbs describing an action, such as he spoke softly; some are modal auxiliaries such as should, might; others involve constructions expressing aspectual information such as continue to. . . . not all adverbials are syntactically adverbs, nor do they resemble one another in semantic contributions. this leads to challenges when disambiguating the actual semantic content in sentences in ucca. consider (1, 2), repeated here as (5, 6): clearly, their meanings are drastically different, but without subcategorization of the d-instances, they receive the same semantic annotation in the ucca foundational layer. adverbials (negation, quantification, modality, manner, etc.) fulfill fundamentally different functions with respect to how the meaning of the rest of the sentence is interpreted. because adverbials (d) cover wide semantic ground, refining the semantic annotation can thus be more informative, along similar lines as refining participants with semantic roles @xcite . foundational layer annotations are inconsistent. beyond the domain of adverbial-proper, another key motivation of d-refinements is to identify sources of disagreement or confusion among the foundational layer categories. while the detailed ucca annotation guidelines serve as a point of reference when choosing between categories, many borderline cases remain. for example, the below d-instance during the last week was identified during our refinement annotation as a borderline case between d-aspectual and t (time), despite being annotated as d. with the proposed refinement, we hope to eliminate such confusion as much as possible, suggesting revisions to the current guidelines as a whole. the goal is to clarify differences between categories such as d-aspectual vs. time, d-possibility vs. ground, etc., the former being in the extension layer and the latter being in the foundational layer. another aspect of foundational layer inconsistency lies in whether or not to treat a unit as unanalyzable, i.e. omitting further internal structure in multiword instances, such as one by one, have to, no longer, no matter how, etc. in the current task, certain adverbial multiword phrases are encountered with different internal structures. while the current refinement does not depend or bear on adverbial internal structures, this is an opportunity for annotators to flag such inconsistencies. with our proposed refinements added, we thus expect the foundational layer consistency to increase. ## agreement studies as a pilot to verify the effectiveness of the subcategorization, three computational linguists familiar with ucca independently annotated adverbial subcategories. two sets of annotation were conducted. the first set involved two annotators. difficulties encountered were used to revise the annotation guidelines, and then a second data sample was annotated by all three annotators. ## discussion based on the results, we turn to some specific challenges with d-refinement annotation, as well as discussing how our scheme relates to two similar representation frameworks. ## conclusion finding an appropriate level of abstraction is a central problem in meaning representation design. motivated by the observation that ucca's adverbial category encompasses too wide a range of heterogeneous semantic functions as a scene-level category, we proposed a semantic refinement annotation scheme consisting of 7 subtypes, allowing multiple annotation to cover a limited amount of compositionality. pilot annotation studies on corpora previously annotated with the ucca foundational layer showed that this subcategorization scheme offers a good coverage of the existing adverbial instances. some challenges remain. though rare, some adverbial instances were marked by annotators as non-applicable under the scheme. we also found that allowing multiple labels can cause annotator disagreement depending on annotators' extent or style of analysis. as more empirical data accrue, future work should aim to mitigate such sources of disagreement.