06/06/2011, 10:42 PM

perhaps not so relevant but the following idea inspires me :

sexp(f(z)) = cheta(f(z))

f(z) satisfies f(z) = f(z) + theta(f(z)) + k

hence theta(f(z)) = -k

but theta is not a constant function , thus there is no f(z) apart from id(z).

sexp(f(z)) = cheta(f(z))

f(z) satisfies f(z) = f(z) + theta(f(z)) + k

hence theta(f(z)) = -k

but theta is not a constant function , thus there is no f(z) apart from id(z).