ERRATUM: Sorry, I made a small mistake in my example. The komi should be 3.5 so white wins by 0.5 if 2 passes end the game. Dave
________________________________ Van: [EMAIL PROTECTED] Verzonden: vr 24-10-2008 10:00 Aan: computer-go Onderwerp: Ending games by two passes Is it correct to end games by 2 consecutive passes? When I learned go 20 years ago I was taught that 3 consecutive passes are required to end a game of go. In practice 2 passes are sufficient in nearly all cases, but sometimes 2 passes is not enough. Suppose we have this position in a 5x5 game with area scoring and 2.5 komi: (0 = white, # = black) ABCDE 5 00### 4 00#+# 3 +0### 2 00##+ 1 0#+## Black has just played C4. The controller is very simple. It only prohibits simple ko (superko is not checked) and all stones left on the board when the game ends are considered alive. White now at C1. Black has no choice but pass and then white quickly passes too. What happens now? If 2 passes end the game, the controller will award a win to white by the komi. If 3 passes are required to end the game, black captures at B1, white has no choice but pass, then black captures at A3 and will (probably) win the game. On could argue that controllers are smarter than the controller in my example, so 2 passes are usually sufficient in pactice, because the controller will query the engines for dead stones. But in my example, wouldn't both engines be justified to declare the white stones alive because of the 2 pass rule? Also, if I am correct, (light) playouts are usually controlled by an internal "controller" that is very similar to the controller in my example. Wouldn't they be vulnerable to this type of situation? Why not avoid this issue simply by requiring 3 consecutive passes to end the game? Am I missing something here? Dave
_______________________________________________ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
