I did not want to spend a lot of time changing Valkyria completely for
integer komi so I made a very simple hack to cope with the fact that I
am using integers and booleans for all computations of wins/losses in
Valkyria. The hack is that every time a jigo occurs in a playout I
randomize which player should win which means the change is very minor
to the program. Thus I d not to model jigo more than in a statiscal
sense.
I am doing some very deep searches to see what could be good moves for
the most important lines in the opening book. I am using the 7.5 komi
book because it is the most developed, but it may be that a 5.5 book
is better if black is favored by 7.0 komi.
Anyway I just looked at a deep search spending 10hours of search,
where old branches of the tree is cut off every time the program runs
out of memory. (Which may also be a part of the problem). It turned
out that search stuck to a PV and played to the end over and over
again with considering other alternatives. Valkyria uses exploration =
0. The game it played over and over was 80 ply deep thanks to a small
kofight and all move looks reasonable although sometimes some moves
look a little odd. It does search alternatives a little bit in each
position but it seems to quickly lock onto something giving 50% for
sure.
My question: Is this normal? Without Jigo this would not be possible
because a deep variation to the absolute end of the game would be a
clear loss for one side and then as the score goes down to 0 the
search will explore many alternatives.
Could it be that playing alternative moves in this search were all too
risky so that search converges on a very long but guaranteed risk free
jigo?
I see this as a problem because if this happens a lot the program
seems not really to search all options probably. It could be that my
program has a bug or twoo that causes this problem, so therefor I am
curious if anyone could reflect on it or have some experience.
I believe chess programs uses something call "contempt" to avoid
drawing too much (I think espeically against weaker opponents).
Best
Magnus
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