tderz: This is the application of the standard tesuji.
tderz: another variation
tderz: Finding the correct first move in (1) as preparation for the tesuji is not difficult.
Everyone who is used to solve problems, has seen it several times and recognizes it at a glance.
The problem solving is always used for the verification? whether the solution really works in the actual circumstances.
Only the diagrams (2), (3) and (4) are in the solution of the Korean book.