Double Trouble: The Problem of Construal in Semantic Annotation of Adpositions

Proceedings of the 6th Joint Conference on Lexical and Computational Semantics (*SEM 2017), pages 178–188, Vancouver, Canada, August 3-4, 2017. c⃝2017 Association for Computational Linguistics Double Trouble: The Problem of Construal in Semantic Annotation of Adpositions Jena D. Hwang and Archna Bhatia IHMC {jhwang,abhatia}@ihmc.us Na-Rae Han University of Pittsburgh naraehan@pitt.edu Tim O’Gorman University of Colorado Boulder timothy.ogorman@colorado.edu Vivek Srikumar University of Utah svivek@cs.utah.edu Nathan Schneider Georgetown University nathan.schneider@georgetown.edu Abstract We consider the semantics of preposi- tions, revisiting a broad-coverage annota- tion scheme used for annotating all 4,250 preposition tokens in a 55,000 word corpus of English. Attempts to apply the scheme to adpositions and case markers in other lan- guages, as well as some problematic cases in English, have led us to reconsider the assumption that an adposition’s lexical con- tribution is equivalent to the role/relation that it mediates. Our proposal is to embrace the potential for construal in adposition use, expressing such phenomena directly at the token level to manage complexity and avoid sense proliferation. We suggest a framework to represent both the scene role and the adposition’s lexical function so they can be annotated at scale—supporting automatic, statistical processing of domain- general language—and discuss how this representation would allow for a simpler inventory of labels. 1 Introduction Prepositions and postpositions (collectively adpo- sitions) are widespread in the world’s languages as grammatical markers expressing spatial, temporal, thematic,1 and other kinds of semantic relations. Unfortunately for semantic processing, a handful of high-frequency types carry an immense payload by way of extreme polysemy. Thus, disambigua- tion of adpositional meaning is crucial to piecing together the interpretation of a sentence (§2). A line of previous work (Srikumar and Roth, 2013a; Schneider et al., 2015, 2016, see §2) has developed a scheme for broad-coverage annotation 1In the sense of thematic roles (agent, patient, etc.). of adpositions with an eye toward building auto- matic disambiguation systems. Their most recent proposal consists of an inventory of 75 categorical labels known as supersenses that characterize the polysemy of English prepositions in a lexically- neutral and coarse-grained fashion. They envision disambiguation as assigning a single one of these supersenses to each preposition token. While formalizing disambiguation via single- label classification works well for prototypical members of the categories, on closer examination, we argue that it is overly simplistic for many us- ages. This became particularly evident when we tried to adapt the English-centric supersense labels to other languages. Here we advance a more nuanced view that an adposition can contribute a semantic perspective, or construal, over and above the scenario relation that its object participates in. We argue that it is essen- tial to distinguish the contribution of the preposi- tion itself, i.e., what the adposition codes for, from the semantic role or relation that the adposition me- diates and that a predicate or scene calls for; and as a result, the label that would be most appropriate is underdetermined for many tokens (§3). In our view, the mismatch can be understood through the lens of construal, …

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