I had someone complain several months ago that CGOS doesn't understand superko and has a bug. It turned out that their program fell on a superko that was really deep. It was rather interesting to see this particular game. I think it's fairly likely with 2 deterministic programs but probably not very likely with Monte Carlo programs since they are very likely to vary their moves.
- Don Jacques Basaldúa wrote: > Michael Wing wrote: > >> In my program (which implements undo), the cost of >> for suicide detection is around 1%, which means it >> would lose 1.5 ELO points. > > In programs that somehow maintain lists of legal moves > or even probability distribution functions over the legal moves, > avoiding suicide is free. I fact, adding the suicide move to the list > would cost. > >> On the other hand detecting superko costs more like >> 6% or so, which costs 9 or more ELO. So a benefit >> of 1 ELO for doing superko right may not be worth >> the cost. > > I guess you mean a bullet proof test from the beginning > of the game. I only test the last 7 moves (if enabled, it can also be > disabled) and that does not cost much. > > The reasons why I use 7 moves are 2: > > * I have never found among strong players a need for > repetition other that triple ko and double ko on a group with no eyes. > (Both are 6 moves long.) My point > is: If the program is so weak that it does silly repetitions, improve > something else. If it is so strong > that it has the same problems as strong humans, detect > superko. > > * My hash system can use only half of the hash (32 bits) > and detect the collision with probability 1. (Because of > the properties of the keys, you need at least 8 keys for a combination > of keys giving zero.) > > A reason I can figure for ignoring repetition in the playouts is: If > the playouts are random, it won't happen much anyway. The probability > of a repetition of 6 random moves is too small to care about. But in > real play it is > frequently a fight for the game. The player forced to > avoid the repetition will resign if it is about the life of a big group. > > > Jacques. > > > _______________________________________________ > computer-go mailing list > [email protected] > http://www.computer-go.org/mailman/listinfo/computer-go/ > _______________________________________________ computer-go mailing list [email protected] http://www.computer-go.org/mailman/listinfo/computer-go/
