All you need to know about Carpenter's Square - 14
We now move on to shapes with the 4-4 points occupied by white. These are much weakened shapes.
We will not discuss this even weaker shape as black is clearly dead.
is simple and effective. Black clearly has insufficient eyespace. If plays 'a', white still replies at to win the capturing race.
works too. The marked stone forces black to fill his own eyespace at so the whole corner is dead.
If black has the extra stone, white can still use Diagram 14.4 to kill the corner. This diagram shows how white would respond to from the other side. is good. Black cannot play 'a' because of insufficient eyespace. If black plays and *b8*, white wins the capturing race by one liberty.
Even if black has an extra liberty at 'a', white can continue to use Diagram 14.4. In case black plays , white can make it a 'Golden Chicken Standing on One Leg' to kill the corner as shown here.
Conclusion: this corner shape is too weak to survive even with either of the two favorable conditions.