8. A system comprising: a processor; and a non-transitory storage device storing instructions which, when executed by the processor, cause the processor to perform a method comprising: identifying a communicative goal in a speech input of a user; generating a plurality of sentence plans based on the communicative goal and a dialog history database, wherein each sentence plan of the plurality of sentence plans is a viable and potentially usable prompt in response to the speech input of the user; ranking the plurality of sentence plans to yield ranked sentence plans; and outputting at least one ranked sentence plan to yield an output sentence plan, wherein the output sentence plan provides a best sentence plan for generating a realization for the communicative goal from among the ranked sentence plans.
8. A system comprising: a processor; and a non-transitory storage device storing instructions which, when executed by the processor, cause the processor to perform a method comprising: identifying a communicative goal in a speech input of a user; generating a plurality of sentence plans based on the communicative goal and a dialog history database, wherein each sentence plan of the plurality of sentence plans is a viable and potentially usable prompt in response to the speech input of the user; ranking the plurality of sentence plans to yield ranked sentence plans; and outputting at least one ranked sentence plan to yield an output sentence plan, wherein the output sentence plan provides a best sentence plan for generating a realization for the communicative goal from among the ranked sentence plans. 14. The system of claim 8 , wherein the communicative goal is generated using recognition and understanding data from an automated dialog system.