We used to write them in BASIC back at the UofIowa in the 80's. Lots of pattern matching for subject and object; lots of dialog trees. It was fun! One observat

We used to write them in BASIC back at the UofIowa in the 80's. Lots of pattern matching for subject and object; lots of dialog trees. It was fun! One observation Bob Bryla made was, count the number of words that begin with 'N' and treat each as a logical-negation. With a very small dictionary of additional negation words (e.g. can't) and a whitelist (e.g. nice) you could tell the sense of a statement or question pretty accurately. Nope, never, not, nada, na, nobody and on and on.