All you need to know about Carpenter's Square - 15
Black's condition appears to be slightly better than in Shape 14 because of the extra bend. What can white do now?
While works well in Diagram 14.4, it doesn't work here. The extra bend is perfect now to enlarge the eyespace. After *b10*, note that white can only form a seki by playing 'a' (this is not Bulky Five).
works well in Diagram 14.3 and it continues to work here. Both and are forcing moves. White can form an eye in the corner to win the capturing race by one liberty. Black 'a' instead of doesn't help either as the common liberty belong to the side with an eye. So black corner is killed.
doesn't feel like a good move but white needs to be careful. is tricked. After *b6*, although black's shape is very ugly, white cannot kill it. is a famous tesuji to create a ko fight.
doesn't work either but black need to know to play instead of 'a'.
Luckily for white, the right solution is still at - easy to remember. is the best move, leaving 'a' and 'b' as miai points, resulting in Eye versus No Eye capturing race.
To summarise: surprisingly the extra bend doesn't help black. White can following either Diagram 15.3 or Diagram 15.6 to kill the corner. Just remember that 1-2 is the key point.