Deriving the Directionality Parameter in OT-LFG
Recent work in Optimality Theoretic Syntax (e.g. Grimshaw 1997, Sells 2001) successfully models positioning of syntactic elements that target a priviledged position in a clause, such as topics, sentential adverbs, operators, and subject, by extending the mechanism of Generalized Alignment (McCarthy and Prince 1993) to the domain of clausal syntax. By allowing only left-alignment, Sells' (2001) work takes a pioneering step towards recasting Kayne's (1994) insightful observation that phrase structure is fundamentally antisymmetric: there is a universal preference for the left-edge the clause, so that the structure is predominantly right-branching. Kayne's (1994) proposal about the antisymmetry of phrase structure essentially represents a derivational view of universal markedness. Symmetric properties of language (e.g. head-complement order) that are traditionally modeled by directionality parameters are derived from an unmarked, antisymmetric structure (e.g. left-specifier, head-initial structure, left-adjunction) by movement. Building on earlier work, the present work further develops a non-derivational theory of phrase structure within OT-LFG. An additional formal mechanism `abutment' (alignment of opposite edges) enables us to produce symmetry without movement. By a principled interaction of abutment with independently movtivated constraints on head positioning and clausal skeleton, we can effectively derive a directionality parameter without losing Kayne's insight about the antisymmetric properties of phrase structure.