Ellipsis Resolution By Controlled Default Unification For Multi-Modal And Speech Dialog Systems

We present a default-unification-based approach to ellipsis resolution that is based on experience in long running multimodal dialog projects, where it played an essential role in discourse processing. We extend default unification to non-parallel structures, which is important for speech and multimodal dialog systems. We introduce new control mechanisms for ellipsis resolution by considering dialog structure with respect to specification, variation and results of tasks and combine this with the analysis of relations between the information elements contained in antecedent and elliptic structures.