1. A method for sentence planning in a task classification system that interacts with a user, comprising: recognizing symbols in a user's single input communication to a task classification system; determining whether the user's input communication can be understood, wherein if the user's communication can be understood, understanding data is generated; generating a plurality of communicative goals based on the recognized symbols and understanding data, the generated plurality of communicative goals being related to information needed to be obtained from the user; in response to information from the user's single input communication: generating a plurality of sentence plans based on the plurality of generated communicative goals, each sentence plan in the plurality of sentence plans being a realization comprising elementary speech acts each corresponding to a respective communicative goal and combined into at least one complete sentence that accomplishes the plurality of communicative goals, and wherein each sentence plan of the plurality of sentence plans is a viable and potentially usable prompt in response to the user's single input communication; independent of the user, ranking the plurality of generated sentence plans; and outputting at least one of the ranked sentence plans to the user as a response to the user's single input communication such that one dialog turn occurs starting with the user's single input communication and ending with the outputted sentence plan.
9. The method of claim 1 , further comprising: determining whether all of the communicative goals have been met; and routing information obtained from the system's interactions with the user for task completion if the determining step determines that all of the communicative goals have been met.