I used to have "solved"-flags in the tree, but the implementation was
so messy and caused bugs in interactions with other messy stuff so I
removed it and was happy.
I guess introducing some other kind of exploration might be better. Or
maybe value jigo as just a little better than losing rather than as
50% but then my simple solution currently is not good enough I would
have to change datatypes and rewrite a lot.
-Magnus
Quoting René van de Veerdonk <[email protected]>:
Magnus,
If you reach a final node, you can mark it as "solved", and never explored
it again. Shouldn't that solve your symptoms? It appears from your
description that you do not have such a feature in your tree-search.
René
On Thu, Mar 31, 2011 at 8:42 AM, <[email protected]> wrote:
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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