Extending Nocuous Ambiguity for Anaphora in Natural Language Requirements

This paper presents an approach to automatically identify potentially nocuous ambiguities, which occur when text is interpreted differently by different readers of requirements written in natural language. We extract a set of anaphora ambiguities from a range of requirements documents, and collect multiple human judgments on their interpretations. The judgment distribution is used to determine if an ambiguity is nocuous or innocuous. We investigate a number of antecedent preference heuristics that we use to explore aspects of anaphora which may lead a reader to favour a particular interpretation. Using machine learning techniques, we build an automated tool to predict the antecedent preference of noun phrase candidates, which in turn is used to identify nocuous ambiguity. We report on a series of experiments that we conducted to evaluate the performance of our automated system. The results show that the system achieves high recall with a consistent improvement on baseline precision subject to some ambiguity tolerance levels, allowing us to explore and highlight realistic and potentially problematic ambiguities in actual requirements documents.