Input TRS:
    1: minus(minus(x)) -> x
    2: minus(+(x,y)) -> *(minus(minus(minus(x))),minus(minus(minus(y))))
    3: minus(*(x,y)) -> +(minus(minus(minus(x))),minus(minus(minus(y))))
    4: f(minus(x)) -> minus(minus(minus(f(x))))
Number of Rules: 4
Direct POLO(mSum) ... failed.