15. A non-transitory computer-readable medium storing software comprising instructions executable by one or more computers which, upon such execution, cause the one or more computers to perform operations comprising: receiving, by a dialog cancellation detector of a system that includes the dialog cancellation detector, a cancellation score database, and a dialog engine, a request that is input at a user device in response to a prompt; identifying, by the dialog cancellation detector, an expected input type that is associated with the prompt; identifying, by the dialog cancellation detector and using the cancellation score database, a cancellation score that is predefined for a potential cancellation term included in the request that is input at the user device in response to the prompt, based on the identified expected input type that is associated with the prompt, wherein the cancellation score that is predefined for the potential cancellation term is different for different expected input types that are associated with different prompts; determining, by the dialog cancellation detector, that the identified cancellation score satisfies a first threshold score; in response to determining that the identified cancellation score satisfies the first threshold score, identifying, by the dialog cancellation detector, the potential cancellation term included in the request that is input at the user device in response to the prompt as a cancellation command; and in response to identifying the potential cancellation term included in the request that is input at the user device as a cancellation command, outputting, by the dialog cancellation detector and to the dialog engine, an indication to the user device that the potential cancellation term included in the request that is input at the user device is a cancellation command rather than a refinement of a previous input.
20. The medium of claim 15 , wherein the expected input type comprises a number input type.