Chrilly wrote:
> I have no finished a plain vanilla 9x9 Suzie-UCT Version. The UCT-tree
> is stored in a Hashtable. I am interested who else uses this approach.

MonteGNU does.

> The reason for using a hashtable was: I was too lazy to implement an
> explicit tree. At least at 9x9 I have no problem with memory size. In
> fact there are 2 hashtables, one for the Alpha-Beta and one for the
> UCT-Version. With the default parameters each version uses 160 MB.
> 
> A chessprogrammer in Go-Land, part X:
> I interpreted SuperKo as repetition of position (which seems to be
> correct, although Stefan Mertin told me, there are numerous versions
> of SuperKo). I used the Nimzo/Hydra code to detect this. But there is
> a - not a very subtle - difference between Go and Chess.
> A move which generates a repetition of position is in Chess legal, in
> Go it is'nt. But I assumed its legal and had quite complicated and
> buggy code to handle this case. I did not know how to evaluate it. It
> came not to my mind, that its just an illegal move and one only has to
> generate the nextbest one.
> Stefan Mertin told me the difference several times, but it did not
> help, only the advice of Peter Woitke, just delete this stupid code,
> was the right instruction level.

It depends on the exact ko rule in use. All reasonable rules have in
common that the immediate one-stone ko recapture (basic ko) is always
forbidden and pass is always allowed. Superko rules forbid repetition;
positional superko forbids a repeated position, situational superko
forbids a repeated position with the same player to play and natural
situational superko is a slight variation on the latter. Japanese rules
allow repetition but if neither player is willing to deviate the game
becomes void and must be replayed. If it happens in time-constrained
amateur tournaments it is instead declared a draw. The Ing ko rule is
understood by few.

In human games it only rarely matters what ko rule is used, for weak
programs it can make a big difference.

/Gunnar
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