Triangulation is losing a move on purpose by walking the king round three squares of a triangle, so the same position returns with the opponent to move.
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Some positions win with the opponent to move and only draw with you to move. If your king has room for a triangle and the enemy king does not, three moves hand the turn over.
How to do it
- 1Check that the position wins with the opponent to move and not with you to move.
- 2Find three squares your king can walk round without letting the enemy king in.
- 3Make sure the enemy king cannot lose a move the same way.
For your level
When a position wins only with the opponent to move, walk your king round a triangle. Three moves later the position is the same and it is their turn.
Common mistakes
- Triangulating when the defending king can also lose a move, so nothing changes.
- Walking a triangle through a square that admits the enemy king.
Questions
- Why does triangulation work?
- Stepping away and back takes two moves; going round a triangle takes three. That one extra move hands the turn to the opponent, provided their king has no room to do the same.
- Can a knight lose a move the way a king can?
- No. A knight always lands on a square of the other colour, so it can never return to a square in an odd number of moves.