Dialog state tracking for assistant systems

In one embodiment, a method includes, by one or more computing systems, receiving, from a client system, an input in a multi-turn message thread, parsing the input to identify a plurality of hypothesis dialog states associated with the input, generating a plurality of functions corresponding to the plurality of hypothesis dialog states, calculating a plurality of probability scores for the plurality of functions, respectively, based on a prior dialog state associated with the message thread and a current user context, wherein each probability score represents a likelihood that the respective function is associated with an intended dialog state, and storing the plurality of functions if each of the probability scores is below a threshold probability score, wherein the plurality of functions is stored as a hierarchical set of functions that is used as the prior dialog state in response to a next input in the message thread.