Input TRS:
    1: active(f(f(a()))) -> mark(c(f(g(f(a())))))
    2: active(f(X)) -> f(active(X))
    3: active(g(X)) -> g(active(X))
    4: f(mark(X)) -> mark(f(X))
    5: g(mark(X)) -> mark(g(X))
    6: proper(f(X)) -> f(proper(X))
    7: proper(a()) -> ok(a())
    8: proper(c(X)) -> c(proper(X))
    9: proper(g(X)) -> g(proper(X))
    10: f(ok(X)) -> ok(f(X))
    11: c(ok(X)) -> ok(c(X))
    12: g(ok(X)) -> ok(g(X))
    13: top(mark(X)) -> top(proper(X))
    14: top(ok(X)) -> top(active(X))
Number of Rules: 14
Direct POLO(mPol) ... failed.