Comparing Two Grammar-Based Generation Algorithms: A Case Study

In this paper we compare two grammar-based generation algorithms: the Semantic-Head-Driven Generation Algorithm (SHDGA), and the Essential Arguments Algorithm (EAA). Both algorithms have successfully addressed several outstanding problems in grammarbased generation, including dealing with non-monotonic compositionality of representation, left-recursion, deadlock-prone rules, and nondeterminism. We concentrate here on the comparison of selected properties: generality, efficiency, and determinism. We show that EAA's traversals of the analysis tree for a given language construct, include also the one taken on by SHDGA. We also demonstrate specific and common situations in which SHDGA will invariably run into serious inefficiency and nondeterminism, and which EAA will handle in an efficient and deterministic manner. We also point out that only EAA allows to treat the underlying grammar in a truly multi-directional manner.