EXPERIENCES WITH PLANNING FOR NATURAL LANGUAGE GENERATION

TLDR

Natural language generation has a long tradition as a planning application, yet mainstream methods largely ignore it, prompting renewed interest in recent studies. The study examines how much recent NLG approaches benefit from advances in planner expressiveness and efficiency, and proposes the domains as challenges for planners. The experiments show that while modern planners can solve the search problems, their runtime is dominated by grounding, and small domain changes shift the balance, making off‑the‑shelf planners unusably slow for nontrivial NLG tasks.

Abstract

Natural language generation (NLG) is a major subfield of computational linguistics with a long tradition as an application area of automated planning systems. While current mainstream approaches have largely ignored the planning approach to NLG, several recent publications have sparked a renewed interest in this area. In this article, we investigate the extent to which these new NLG approaches profit from the advances in planner expressiveness and efficiency. Our findings are mixed. While modern planners can readily handle the search problems that arise in our NLG experiments, their overall runtime is often dominated by the grounding step they perform as preprocessing. Furthermore, small changes in the structure of a domain can significantly shift the balance between search and preprocessing. Overall, our experiments show that the off‐the‐shelf planners we tested are unusably slow for nontrivial NLG problem instances. As a result, we offer our domains and experiences as challenges for the planning community.