1) Chess problem 
[chess] One simple example of such a pattern is `triangulation` in a king and pawn endgame, such as in the diagrammed position. Here, the white king triangulates and thus loses a move in order to put Black in zugzwang. The winning idea continues 1.Kd5 Kc8 2. Kd4 Kd8 3.Kc4 Kc8 4.Kd5 Kc7 5.Kc5 and the rundlauf is complete. In Johnathan Levitt...