A Lexicon of Discourse Markers for Portuguese – LDM-PT

A Lexicon of Discourse Markers for Portuguese – LDM-PT Amália Mendes1, Iria del Rio1, Manfred Stede2, Felix Dombek2 1 University of Lisbon, Centre of Linguistics, Portugal 2 University of Potsdam, Germany amaliamendes@letras.ulisboa.pt, igayo@gmail.com, stede@uni-potsdam.de, felix_dombek@hotmail.com Abstract We present LDM-PT, a lexicon of discourse markers for European Portuguese, composed of 252 pairs of discourse marker/rhetorical sense. The lexicon covers conjunctions, prepositions, adverbs, adverbial phrases and alternative lexicalizations with a connective function, as in the PDTB (Prasad et al., 2008; Prasad et al., 2010). For each discourse marker in the lexicon, there is information regarding its type, category, mood and tense restrictions over the sentence it introduces, rhetorical sense, following the PDTB 3.0 sense hierarchy (Webber et al., 2016), as well as a link to an English near-synonym and a corpus example. The lexicon is compiled in a single excel spread sheet that is later converted to an XML scheme compatible with the DiMLex format (Stede, 2002). We give a detailed description of the contents and format of the lexicon, and discuss possible applications of this resource for discourse studies and discourse processing tools for Portuguese. Keywords: Discourse markers, Lexicon, Discourse treebank 1. Introduction The Lexicon of Discourse Markers (LDM-PT) provides a set of lexical items in Portuguese that have the function of structuring discourse and ensuring textual cohesion and coherence at intra-sentential and inter-sentential levels (Halliday & Hasan, 1976). Each discourse marker (DM) is associated to the set of its rhetorical senses (also named discourse relations or coherence relations), following the PDTB 3.0 sense hierarchy (Webber et al., 2016). We consider that discourse connectives do not vary regarding inflection, they express a two-place semantic relation, have propositional arguments and are not integrated in the predicative structure. This includes conjunctions, adverbs and adverbial phrases, but also prepositions and alternative lexicalizations, as we discuss in section 4. Our immediate goal is to provide data for the annotation of discourse relations in a Portuguese discourse treebank, although a listing of DMs will certainly prove to be useful for applications dealing with tasks such as parsing, text processing and summarization of Portuguese. We revisit in Section 2 other lexicons of DMs, their features and structure schemata; we discuss in Section 3 the acquisition of the DMs that we integrate in our lexicon and in Section 4 the information provided for each DM. In Section 5, we present the way this information is structured and the result in XML format, while we discuss in Section 6 the use of such a lexicon in discourse studies and its applications in the automatic processing of discourse. Finally, we provide some concluding remarks in sSection 7. 2. Related work A lexicon of DMs may be restricted to discourse connectives, i.e., devices that assure cohesion at intra and inter-sentential levels (typically, conjunctions and adverbial phrases) or it can have a larger scope by also including pragmatic markers with interactional and modal meanings (Cuenca and Marín, 2009). Even under a more restrictive perspective, there are differences in the set of categories …

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