A Phrasal Approach to Natural Language Interfaces over Databases

This short paper introduces the STEP system for natural language access to relational databases. In contrast to most work in the area, STEP adopts a phrasal approach; an administrator couples phrasal patterns to elementary expressions of tuple relational calculus. This ‘phrasal lexicon' is used bi-directionally, enabling the generation of natural language from tuple relational calculus and the inverse parsing of natural language to tuple calculus. This ability to both understand and generate natural language enables STEP to engage the user in clarification dialogs when the parse of their query is of questionable quality or is open to multiple interpretations. An on-line demonstration of STEP is accessible at http://www.cs.umu.se/~mjm/step.