HaG — A Computational Grammar ofHausa

In this paper, I shall give an overview of HaG (=Hausa Grammar), an emerging computational grammar of Hausa1, developed within the framework of Head-driven Phrase Structure (Pollard and Sag, 1987, 1994; Sag, 1997). Since HPSG is an integrated theory of syntax and semantics, meaning representations are built up in tandem with syntactic analysis. Semantics in HaG are represented using Minimal Recursion Semantics (MRS; Copestake, Flickinger, Pollard and Sag, 2005), essentially providing predicate-argument structures with an unspecified representation of (quantifier) scope. The grammar described in this paper runs on top of the Lingo Linguistic Knowledge Builder (LKB; Copestake, 2002), a platform for typed feature structure grammars originally developed at CSLI, Stanford. The LKB system not only provides a bottom-up chart parser (Oepen and Carroll, 2000), but also a chart generator (Carroll, Copestake, Flickinger and Poznanski, 1999; Carroll and Oepen, 2000). Consequently, HaG was designed from the start as a reversible grammar, i.e. a grammar that is suitable for both analysis and synthesis. In addition to the development platform LKB, HaG can also be run using the efficient C++ parser Pet (Callmeier, 2000), and since autumn 2011, on the reversible ace parser/generator developed in C by Woodley Packard (http://sweaglesw.org/linguistics/ace/). The grammar, as well as all the development and run-time systems, are available under free and open source licenses. As an alternative to a full-fledged install of the grammar and development systems, we provide a web demo (http://hag.delph-in.net) which provides a concise interface to the grammar, displaying full semantic representations, as well as the constituent structure. Development of the grammar started in 2009, based on the LinGO grammar matrix (Bender, Flickinger and Oepen, 2002), a core system of basic types extracted from the English Resource Grammar (ERG; Copestake and Flickinger, 2000) which ensures basic compatibility of semantic representations between LKB grammars using MRS. Implementation of a formal grammar of Hausa is motivated by two major goals: first, the availability of an implemented grammar will contribute a reusable linguistic resource for a computationally underresourced language. Second, the implementation of a competence grammar based on a linguistically motivated formalism such as HPSG will provide testable models of linguistic theories. Since HaG is the first implemented grammar of a tone language that systematically integrates suprasegmental phonology, we hope to also further our understanding of the computational treatment of (African) tone languages. Current development of HaG focuses on the implementation of syntactic constructions and the system of morpho-syntactic rules. This decision is deliberate, since we plan to expand the lexicon using grammar-based machine learning techniques (Zhang and Kordoni, 2006). As a result, the grammar already covers a substantial part of Hausa core grammar, despite the comparatively small lexicon. In this paper, I shall provide an overview of the main constructions of the language as implemented in HaG. Following a detailed overview of the central issues concerning the treatment of tone and length (section 1), I shall briefly discuss the implementation of inflectional morphology (section 2). Section 3 will be devoted to morpho-syntax, including direct object marking, mixed categories, and pronominal