public Derivation switchVars(VarInfo[] old_vars, VarInfo[] new_vars) {
   TernaryDerivation result = this.clone();
   result.base1 = new_vars[ArraysMDE.indexOf(old_vars, result.base1)];
   result.base2 = new_vars[ArraysMDE.indexOf(old_vars, result.base2)];
   result.base3 = new_vars[ArraysMDE.indexOf(old_vars, result.base3)];
   return result;
 }
  public InvariantStatus add_modified(double[] a, int count) {
    // System.out.println ("common: " + ArraysMDE.toString (a));
    if (a == null) {
      return InvariantStatus.FALSIFIED;
    } else if (intersect == null) {
      intersect = a;
      return InvariantStatus.NO_CHANGE;
    } else {
      double[] tmp = new double[intersect.length];
      int size = 0;
      for (int i = 0; i < a.length; i++) {
        // if (a[i] in intersect) && !(a[i] in tmp), add a[i] to tmp
        int ii = Global.fuzzy.indexOf(intersect, a[i]);
        if ((ii != -1) && (Global.fuzzy.indexOf(ArraysMDE.subarray(tmp, 0, size), a[i]) == -1)) {
          // System.out.println ("adding " + intersect[ii] + " at " + size);

          // Carefully add the existing intersect value and not a[i].  These
          // are not necessarily the same when fuzzy floating point
          // comparisons are active.
          tmp[size++] = intersect[ii];
        }
      }
      if (size == 0) {
        return InvariantStatus.FALSIFIED;
      }

      intersect = ArraysMDE.subarray(tmp, 0, size);
    }

    intersect = Intern.intern(intersect);
    elts++;
    return InvariantStatus.NO_CHANGE;
  }
 public InvariantStatus add_modified(long[] a1, long[] a2, int count) {
   if (logDetail())
     log(
         debug,
         "saw add_modified (" + ArraysMDE.toString(a1) + ", " + ArraysMDE.toString(a2) + ")");
   return check_modified(a1, a2, count);
 }
  public InvariantStatus check_modified(long[] a1, long[] a2, int count) {
    if ((a1 == null) || (a2 == null)) return InvariantStatus.FALSIFIED;

    int result = ArraysMDE.indexOf(a2, a1);

    if (result == -1) return InvariantStatus.FALSIFIED;
    else return InvariantStatus.NO_CHANGE;
  }