Key for EGTB Analysis

Guy Haworth and Ken Regan, drawing on John Nunn

The first three annotations are for moves that might not deserve the standard ! or !! annotations.

A move that minimizes the time for the winner to mate, or maximizes the length of time the defender can delay mate. (There may be more than one such move.)
A move that is necessary to win---other moves either draw or allow the defender to force a return to the current position.
The unique move to achieve a win for the attacker or a draw for the defender.

The next three show different senses of Zugzwang.

Zugzwang in weakest sense: attacker to move takes longer to win than would be the case if the defender had to move.
Zugzwang: Defender is to move; attacker to move needs to bring about this position with the defender to move in order to win.


Zugzwang in the strongest sense (and the purist's sense): Defender to move loses, but attacker to move only draws (or loses).