f(a2(),x) -> x
a1() -> i1(a2())
f(x,i2(x)) -> a2()
i2(a2()) -> a2()
f(f(x,y),z) -> f(x,f(y,z))
f(x,f(i2(x),y)) -> y
f(x,a2()) -> i2(i2(x))
f(i2(i2(x)),y) -> f(x,y)
f(i2(x),f(x,y)) -> y
i2(i2(i2(x))) -> i2(x)
i2(f(x,y)) -> f(i2(y),i2(x))
f(x,i1(x)) -> i1(a2())
f(x,i1(a2())) -> i1(i2(x))
i1(i2(i2(x))) -> i1(x)
i2(i1(x)) -> i2(i2(x))
i1(i1(x)) -> i1(i2(x))
f(i1(x),y) -> f(i2(x),y)
i1(f(x,y)) -> f(i2(y),i1(x))