  We present ShopTalk, a multi-turn conversational faceted search system for
shopping that is designed to handle large and complex schemas that are beyond
the scope of state of the art slot-filling systems. ShopTalk decouples dialog
management from fulfillment, thereby allowing the dialog understanding system
to be domain-agnostic and not tied to the particular shopping application. The
dialog understanding system consists of a deep-learned Contextual Language
Understanding module, which interprets user utterances, and a primarily
rules-based Dialog-State Tracker (DST), which updates the dialog state and
formulates search requests intended for the fulfillment engine. The interface
between the two modules consists of a minimal set of domain-agnostic "intent
operators," which instruct the DST on how to update the dialog state. ShopTalk
was deployed in 2020 on the Google Assistant for Shopping searches.
