3-3 invasion, continued  

Discussion

Historically, invading the 3–3 point early in the game was considered bad because it was believed that this variation gave the non-invading player superior outward influence. This evaluation of this variation has not changed with the advent of AI. What has changed however is the realisation that the hane is a mistake: the hane-connection gives Black too much thickness. By omitting it White does get a satisfactory result.

Responding to a 4-4 opening with a 3–3 invasion early in the game is now considered acceptable. AI have come up with many new joseki starting with the 3-3 invasion that have become extremely popular in both professional and amateur games. Nowadays, White will either tenuki or play at 'a', and will never play the hane . See 4-4 Point 3-3 Invasion, Hane-Extend. And Black has several alternatives instead of the marked stone: see 4-4 point 3-3 invasion joseki.

References