public static Keyword tryShallowDisproof(ControlFrame frame) {
    { Proposition proposition = frame.proposition;

      if (!Proposition.allArgumentsBoundP(proposition)) {
        return (Logic.KWD_FAILURE);
      }
      else if (ControlFrame.hasShallowDisproofP(frame)) {
        { boolean hasdefaultdisproofP = (frame.truthValue == Logic.DEFAULT_TRUE_TRUTH_VALUE) ||
              (frame.truthValue == Logic.DEFAULT_FALSE_TRUTH_VALUE);

          if (hasdefaultdisproofP) {
            ControlFrame.setFrameTruthValue(frame, null);
          }
          return ((hasdefaultdisproofP ? Logic.KWD_FAILURE : Logic.KWD_TERMINAL_FAILURE));
        }
      }
      return (Logic.KWD_FAILURE);
    }
  }