--Finished modifications to generator/recognizer/parser to use unified definitions of word types.  Since the word groups are now defined as a single list--i.e., (define objects '(the-table the-chair))--instead of individual single-word lists, I couldn't use (either a b) in the generator.  I first tried (list (a-member-of objects)), but that didn't work with the parser because the parser expected a pair.  I instead used (cons (a-member-of objects) '()), which seems to work fine with the parser and recognizer.