This kata covers the Greenberger-Horne-Zeilinger game (often abbreviated as GHZ game), a well-known example of a nonlocal (entanglement) game.

In a nonlocal game, several cooperating players play a game against a referee answering the referee's questions. The players are free to share information (and even qubits!) before the game starts, but are forbidden from communicating with each other afterwards. Nonlocal games show that quantum entanglement can be used to increase the players' chance of winning beyond what would be possible with a purely classical strategy.

• Lecture 1 by Michael Walter.
• Lecture 20 by John Watrous.