14. The method of claim 12 , further comprising: retrieving a training database that includes a set of learned rules, wherein the ranking step is performed using the set of learned rules.
12. A method for automatically planning a sentence based on communicative goals, the communicative goals being related to information needed to be obtained from a user, the method comprising: generating and storing via a processor a plurality of sentence plans based on the communicative goals and on a dialog history database comprising previously gathered dialogs and a present dialog to yield generated sentence plans, wherein each sentence plan of the plurality of generated sentence plans comprises an unordered set of elementary speech acts encoding the communicative goals, each speech act assigned a canonical lexico-structural representation, and wherein each sentence plan of the plurality of generated sentence plans is a viable and potentially usable prompt in response to a single communication from the user; ranking, independent of the user, the plurality of generated sentence plans; selecting a highest ranked sentence plan of the plurality of generated sentence plans to yield a selected sentence plan; realizing the selected sentence plan to yield a realized sentence plan; and outputting the realized sentence plan to yield an output sentence plan, wherein each needed communicative goal of the communicative goals is addressed by the output sentence plan.