[SiR ZigZag NeaRton]

[(~p$\rightarrow$~q)^(~r$\rightarrow$ ~s)]v[(~p$\rightarrow$ r )^(s$\rightarrow$ ~q)]
[F$\rightarrow$T]^(F$\rightarrow$S)]V[(F$\rightarrow$T)^(s$\rightarrow$T)]
(T^T)V(T^T)=T