public static Keyword tryRefutationProof(ControlFrame frame) {
    { ParallelThread parallelthread = ((QueryIterator)(Logic.$QUERYITERATOR$.get())).currentParallelThread;
      ParallelControlFrame parallelframe = ((ParallelControlFrame)(parallelthread.topControlFrame.up));

      if (parallelframe.unboundVariablesP) {
        return (Logic.KWD_FAILURE);
      }
      ParallelControlFrame.enterHypotheticalWorld(parallelframe);
      try {
        { boolean negatedtruthvalueP = frame.reversePolarityP;

          { Proposition prop = null;
            Cons iter000 = Proposition.inheritAsTopLevelProposition(frame.proposition, null);

            for (;!(iter000 == Stella.NIL); iter000 = iter000.rest) {
              prop = ((Proposition)(iter000.value));
              if ((Stella.$TRACED_KEYWORDS$ != null) &&
                  Stella.$TRACED_KEYWORDS$.membP(Logic.KWD_GOAL_TREE)) {
                {
                  System.out.println();
                  System.out.println("  Assume that " + prop + " is " + ((negatedtruthvalueP ? "true" : "false")) + ".");
                }
;
              }
              Proposition.recursivelyFastenDownPropositions(prop, false);
              Proposition.assignTruthValue(prop, (negatedtruthvalueP ? Stella.TRUE_WRAPPER : Stella.FALSE_WRAPPER));
            }
          }
        }
      } catch (Clash e000) {
        return (Logic.KWD_FINAL_SUCCESS);
      }
      return (Logic.KWD_FAILURE);
    }
  }