Task-oriented dialog (TOD) systems often require interaction with an external
knowledge base to retrieve necessary entity (e.g., restaurant) information to
support the response generation. Most current end-to-end TOD systems either
retrieve the KB information explicitly or embed it into model parameters for
implicit access.~While the former approach demands scanning the KB at each turn
of response generation, which is inefficient when the KB scales up, the latter
approach shows higher flexibility and efficiency. In either approach, the
systems may generate a response with conflicting entity information. To address
this issue, we propose to generate the entity autoregressively first and
leverage it to guide the response generation in an end-to-end system. To ensure
entity consistency, we impose a trie constraint on entity generation. We also
introduce a logit concatenation strategy to facilitate gradient backpropagation
for end-to-end training. Experiments on MultiWOZ 2.1 single and CAMREST show
that our system can generate more high-quality and entity-consistent responses.Comment: Accepted to COLING 202