Input TRS:
    1: active(f(f(X))) -> mark(c(f(g(f(X)))))
    2: active(c(X)) -> mark(d(X))
    3: active(h(X)) -> mark(c(d(X)))
    4: mark(f(X)) -> active(f(mark(X)))
    5: mark(c(X)) -> active(c(X))
    6: mark(g(X)) -> active(g(X))
    7: mark(d(X)) -> active(d(X))
    8: mark(h(X)) -> active(h(mark(X)))
    9: f(mark(X)) -> f(X)
    10: f(active(X)) -> f(X)
    11: c(mark(X)) -> c(X)
    12: c(active(X)) -> c(X)
    13: g(mark(X)) -> g(X)
    14: g(active(X)) -> g(X)
    15: d(mark(X)) -> d(X)
    16: d(active(X)) -> d(X)
    17: h(mark(X)) -> h(X)
    18: h(active(X)) -> h(X)
Number of Rules: 18
Direct QWPOS(Pol) ... failed.