g ( x , y ) = ψ ( x ) ( y ) {\displaystyle g(x,y)=\psi ^{(}x)(y)}
g ( 0 , y ) = y {\displaystyle g(0,y)=y} g ( x + 1 , y ) = ψ ( g ( x , y ) ) {\displaystyle g(x+1,y)=\psi (g(x,y))}
f ( x ) = g ( x , x ) = ψ ( x ) ( x ) {\displaystyle f(x)=g(x,x)=\psi ^{(}x)(x)}
g(x,y,z,0) = x g ( x , y , z , w + 1 ) = ϕ ( g ( x , y , z , w ) , z − x ) {\displaystyle g(x,y,z,w+1)=\phi (g(x,y,z,w),z-x)}
- es el menos natural (con puntito arriba)
f ( x , y ) = g ( x , y , y , y + 1 ) {\displaystyle f(x,y)=g(x,y,y,y+1)}