6. Attack Weak Stones!
A Dubious Approach Move

by Richard Bozulich

One of the basic strategic principles of go is to avoid leaving behind weak groups that your opponent can attack. If you do have any weak groups, strengthening them should be your first priority. On the other hand, if you find that your opponent has a weak group, you should attack it as soon as possible. In the process of attacking it, you should be able to secure territory, gain influence, or both. You can find many examples and problems on this topic in Attacking and Defending Weak Groups.

Black to play
Problem. Black to play
Considering the principle mentioned in the introduction above, doesn't it seem strange for White to have approached inside Black's sphere of influence with the marked stone? White has instantly created a weak stone for Black to attack. How can Black use his material advantage to punish White for this dubious invasion?