39. A non-transitory computer readable medium containing computer-executable instructions for providing a cooperative conversational voice user interface, the computer-executable instructions operable when executed to: receive an utterance at a voice input device during a current conversation with a user; accumulate short-term shared knowledge about the current conversation, wherein the short-term shared knowledge includes knowledge about the utterance received during the current conversation; accumulate long-term shared knowledge about the user, wherein the long-term shared knowledge includes knowledge about one or more past conversations with the user; identify a context associated with the utterance, wherein a conversational speech engine identifies the context associated with the utterance from the short-term shared knowledge and the long-term shared knowledge; infer additional information about the utterance from the short-term shared knowledge and the long-term shared knowledge in response to determining that the utterance contains insufficient information to complete a request in the identified context; establish an intended meaning for the utterance within the identified context based on the additional information inferred about the utterance; and generate a response to the utterance based on the intended meaning established within the identified context.
39. A non-transitory computer readable medium containing computer-executable instructions for providing a cooperative conversational voice user interface, the computer-executable instructions operable when executed to: receive an utterance at a voice input device during a current conversation with a user; accumulate short-term shared knowledge about the current conversation, wherein the short-term shared knowledge includes knowledge about the utterance received during the current conversation; accumulate long-term shared knowledge about the user, wherein the long-term shared knowledge includes knowledge about one or more past conversations with the user; identify a context associated with the utterance, wherein a conversational speech engine identifies the context associated with the utterance from the short-term shared knowledge and the long-term shared knowledge; infer additional information about the utterance from the short-term shared knowledge and the long-term shared knowledge in response to determining that the utterance contains insufficient information to complete a request in the identified context; establish an intended meaning for the utterance within the identified context based on the additional information inferred about the utterance; and generate a response to the utterance based on the intended meaning established within the identified context. 40. The non-transitory computer readable medium of claim 39 , wherein the established intended meaning comprises an implicit hypothesis having a corresponding degree of certainty about an intent that the user had in speaking the utterance.