static SS ai_negateVerb_map = asCaseInsensitiveMap(litorderedmap_bidi("is not", "is", "isn't", "is", "are", "aren't", "am", "am not", "was", "wasn't", "can", "can't");

static S ai_negateVerb(S verb) {
  try answer mapGet(ai_negateVerb_map, verb);
  if (endsWithIC(verb, " not")) ret dropSuffixICTrim("not", verb);
  
  // Try first word
  L<S> tok = nlTok(verb);
  S s = mapGet(ai_negateVerb_map, second(tok));
  if (s != null) ret s + joinSubList(tok, 2);
  
  if (isThirdPersonVerb(verb)) ret "doesn't " + verbToBaseForm(verb);
  ret "don't " + verb;
}