Lately I have been trying to prove axiom of choice based on krull theorem. The theorem states that for every ring with a unit $R$ that is not a field, there is a maximal ideal. I know it is equivalent to AC. What i have so far is: let $S$ be a set such that $\cup S \neq \phi$. Let's build a ring: $$$$ $R=P(S)$ ;$\oplus=XOR$, $\odot=\phi$ ; $\otimes=\cap$, $1=\{S\}$ $$$$It is a ring, moreover: for every $x\epsilon R$, $(-x)=x$. Also, it is not a field because for every $x\epsilon R$, $x\neq phi$ $x^{-1}$ does not exit. $$$$From this i can deduce that exits a maximal ideal.
That is all have. how do i continue??