Towards Convenient Bi-Directional Grammar Formalisms

This paper discusses the advantages for practical bi-directional grammars of combining a lexical focus with the GPSG-originated principle of immediate-dominance/linear-precedence (ID/LP) rule partitioning. It also outlines an implementation approach following these guidelines. The approach is inspired by Slot Grammar, with additions including more explicit mappings between surface and internal representations, and preferential constituent ordering rules.