ambigious phrase or phrase token -> multiple possibilities the parser can handle -> multiple possibilities from the requester -> repeat until you've dialed down to a single possibility.

It's a big part of what the Machine Learning guys and the NLP guys are doing. But, as mentioned, there's very little context for a computer to work with...so everything is very specific. "google, find me movie theatres in the area" vs "i wonder what movies are around. do you have any ideas google?".