(VAR F X Y Z )
(RULES 
        min(s(X), s(Y)) -> min(X, Y)
        min(X, 0) -> 0
        min(0, X) -> 0
        min(nul(F, Y), Z) -> nul(F, min(Y, Z))
        nul(F, X) -> find0(F, 0, X)
        find0(F, X, 0) -> X
        find0(F, X, s(Y)) -> if(, find0(F, s(X), Y), X)
        if(s(Z), X, Y) -> X
        if(0, X, Y) -> Y
        
)