Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2009/ii/paper-3/12f/a/solution

The polynomial form of the Runge approximation theorem says: if is compact, is connected, and is holomorphic on a neighborhood of , then for every there is a polynomial with . Choosing errors tending to zero gives a uniformly convergent sequence of polynomials. Equivalently, on an open domain with connected complement in the Riemann sphere, every holomorphic function is the compact-uniform limit of polynomials. The connected-complement hypothesis excludes enclosed holes containing poles of the function being approximated.

New to topics? Read the docs here!