If I have an analytic function in plane f(x,y) $F(x,y)$ that is zero on a curve y=f(x), $y=f(x)$, is it true that f=(y-f(x))^n h$F=(y-f(x))^n h$, where h $h$ is nonzero on the curve? More general, can be somethink said about factorisation of analytic functions? How much is it determined by its zero set? Thx