  This paper summarizes our entries to both subtasks of the first DialDoc
shared task which focuses on the agent response prediction task in
goal-oriented document-grounded dialogs. The task is split into two subtasks:
predicting a span in a document that grounds an agent turn and generating an
agent response based on a dialog and grounding document. In the first subtask,
we restrict the set of valid spans to the ones defined in the dataset, use a
biaffine classifier to model spans, and finally use an ensemble of different
models. For the second subtask, we use a cascaded model which grounds the
response prediction on the predicted span instead of the full document. With
these approaches, we obtain significant improvements in both subtasks compared
to the baseline.
