EQUATIONS: 
f(x,f(y,z)) = f(f(x,y),z)
f(x,i(x)) = e()
f(x,e()) = x
f(e(),x) = x
i(f(y,x)) = f(i(x),i(y))

COMPLETE TRS:
RULES:
f(x,i(x)) -> e()
f(x,e()) -> x
f(e(),x) -> x
i(f(y,x)) -> f(i(x),i(y))
f(i(x),x) -> e()
f(f(x,y),z) -> f(x,f(y,z))
i(e()) -> e()
f(y,f(i(y),x)) -> x
i(i(x)) -> x
f(i(y),f(y,x)) -> x

SUCCESS
MaxTRS: 4 
Search time: 1.10 seconds