Input TRS:
    1: :(x,x) -> e()
    2: :(x,e()) -> x
    3: i(:(x,y)) -> :(y,x)
    4: :(:(x,y),z) -> :(x,:(z,i(y)))
    5: :(e(),x) -> i(x)
    6: i(i(x)) -> x
    7: i(e()) -> e()
    8: :(x,:(y,i(x))) -> i(y)
    9: :(x,:(y,:(i(x),z))) -> :(i(z),y)
    10: :(i(x),:(y,x)) -> i(y)
    11: :(i(x),:(y,:(x,z))) -> :(i(z),y)
Number of Rules: 11
Direct POLO(mSum) ... failed.