ndkrempel?: Well if white wants to try anything, it has to be one of the three marked points, so let's try them in turn.
ndkrempel?: From here, the four white stones cannot escape and cannot make a nakade shape: black is alive.
ndkrempel?: Black captures some stones to make a living shape. 3 can also be at 5, but not at 4 or 6.
ndkrempel?: Again black can capture the stones and live without having to fight a ko.