MAYBE
MAYBE
TRS:
 {
        f(x, y, mark(z)) -> mark(f(x, y, z)),
  f(ok(x), ok(y), ok(z)) -> ok(f(x, y, z)),
      active(f(x, y, z)) -> f(x, y, active(z)),
  active(f(b(), c(), x)) -> mark(f(x, x, x)),
             active(d()) -> mark(c()),
             active(d()) -> m(b()),
      proper(f(x, y, z)) -> f(proper(x), proper(y), proper(z)),
             proper(b()) -> ok(b()),
             proper(c()) -> ok(c()),
             proper(d()) -> ok(d()),
            top(mark(x)) -> top(proper(x)),
              top(ok(x)) -> top(active(x))
 }
 DUP: We consider a duplicating system.
  Trs:
   {
          f(x, y, mark(z)) -> mark(f(x, y, z)),
    f(ok(x), ok(y), ok(z)) -> ok(f(x, y, z)),
        active(f(x, y, z)) -> f(x, y, active(z)),
    active(f(b(), c(), x)) -> mark(f(x, x, x)),
               active(d()) -> mark(c()),
               active(d()) -> m(b()),
        proper(f(x, y, z)) -> f(proper(x), proper(y), proper(z)),
               proper(b()) -> ok(b()),
               proper(c()) -> ok(c()),
               proper(d()) -> ok(d()),
              top(mark(x)) -> top(proper(x)),
                top(ok(x)) -> top(active(x))
   }
  Fail