Key for EGTB
Guy Haworth and Ken
Regan, drawing on John Nunn
The first three annotations are
for moves that might not deserve the standard ! or !!
- 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
- 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).