Later - is sente. Black gets 19 points of territory, while White gets 14 points, for a net local score of +5.
is a mistake. and catch the Black stones in a connect and die.
The descent, , is Black's correct play. Later - is White's sente.
Black gets 22 points, while White gets 14, for a net score of +8. So gains 3 points.
Anonymous: Isn't this a bit better? After this, a is gote for white. Since black can also hane at b for a point in gote, the score is the same. However, white has a lot less ko threats here.
Bill: This is also a solution. Which is better depends on the rest of the board.
Charles is a nice play. I hardly meet any beginners who would find this, except by accident, though. In a game finding would be a sign of about 1 kyu level, I guess.