Beginner Exercise 143 / Solution

Solution  

White has two effective sente moves (called kiki in Japanese), a and b, against the Black corner. ensures connection or ko for kill in the corner against any Black try. For example....

Black try 1  

Against , makes a and b miai. This also works against at a or c.

Ko for life for both sides  

Though Black takes first, White has good local ko threats at a and b.

Black try 2  

here can't prevent connection.

Black try 3 ( at )  

This is not ko.

Total Failure  

can't connect.

Big loss  

is better than above, but is a big endgame play anyway. Black can later invade as far as a. As a general rule, keep powerful sente moves for later use for flexibility.