Input TRS:
    1: active(c()) -> mark(f(g(c())))
    2: active(f(g(X))) -> mark(g(X))
    3: proper(c()) -> ok(c())
    4: proper(f(X)) -> f(proper(X))
    5: proper(g(X)) -> g(proper(X))
    6: f(ok(X)) -> ok(f(X))
    7: g(ok(X)) -> ok(g(X))
    8: top(mark(X)) -> top(proper(X))
    9: top(ok(X)) -> top(active(X))
Number of Rules: 9
Direct QKBOS(Sum) ... failed.