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