[computer-go] KO in Hashtable-UCT?

[Don Dailey]

I don't think you can ignore superko in the UCT search - you will lose
games.   You will also lose games even if you only check the move you
will actually play in the game.   

But in the play-outs, it has almost no value whatsoever, even if it 
was free.   (It probably has SOME value, but miniscule and clearly 
would weaken the program because you would do less play-outs in a
given amount of time.)

If you keep superko tests in the UCT tree, you have a scalable
program.

- Don



On Fri, 2007-05-18 at 09:33 -0700, Peter Drake wrote:
> True...
> 
> 
> My experience has been that (largely) ignoring the extremely rare case
> of superko is a better use of the finite resources we have.
> 
> 
> Have others found the same thing?
> 
> Peter Drake
> http://www.lclark.edu/~drake/
> 
> 
> 
> 
> 
> On May 18, 2007, at 9:19 AM, Chris Fant wrote:
> 
> > > After search, when actually making a move:
> > > 1) Make a copy of the board
> > > 2) Compute the Zobrist hash of the current position from scratch
> > > 3) Check for superko violations (against a stack of previous
> > > Zobrist hashes
> > > for positions in the real game,)
> > > 4) If there is a violation, go back to the copy and try the next
> > > best move
> > 
> > 
> > But then you have an engine which does not converge to perfect play
> > given infinite resources.
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> 
> 
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