A symbolic description of punning riddles and its computer   implementation
  Riddles based on simple puns can be classified according to the patterns of word, syllable or phrase similarity they depend upon. We have devised a formal model of the semantic and syntactic regularities underlying some of the simpler types of punning riddle. We have also implemented this preliminary theory in a computer program which can generate riddles from a lexicon containing general data about words and phrases; that is, the lexicon content is not customised to produce jokes. Informal evaluation of the program's results by a set of human judges suggest that the riddles produced by this program are of comparable quality to those in general circulation among school children. 
Kim Binsted (Department of Artificial Intelligence, University of   Edinburgh), Graeme Ritchie (Department of Artificial Int...