TIMEOUT
MAYBE
Trs:
 {      g(ok(X)) -> ok(g(X)),
        h(ok(X)) -> ok(h(X)),
     proper(c()) -> ok(c()),
     proper(d()) -> ok(d()),
    proper(g(X)) -> g(proper(X)),
    proper(h(X)) -> h(proper(X)),
     active(c()) -> mark(d()),
    active(g(X)) -> mark(h(X)),
  active(h(d())) -> mark(g(c())),
    top(mark(X)) -> top(proper(X)),
      top(ok(X)) -> top(active(X))}
 Open