Two qick comments:
Quoting Matt Gokey <[EMAIL PROTECTED]>:
Jacques Basaldúa wrote:
Very good analysis and I would like to contribute a 4th reason:
against scalability of global search MC/UCT. If the simulation is
500 moves long (Chinese rules with recaptures, etc.) the observed
variance at an early move blurs out everything.
This is not a problem for "scalability" for MC/UCT. It just means that
a program
that is 5 kyu with 10 minutes on 9x9 might be 35 kyu with 10 minutes on 19x19.
Yet for both 9x9 and 19x19 it holds that a bugfree implementation of
MC/UCT will
assymptotically reach perfect play when thinking time goes towards infinity.
True is that going from 9x9 to 19x19 is frustrating. But this is because 19x19
is more complex than 9x9. An MC/UCT program is still very much better than
random play because random plays need more than 100 free handicap stones to
have a chance on 19x19.
Good point. This leads to another thought that I have been wondering
about. That is I question whether using more time to search more
simulations in the opening is the best approach. For the opening,
selecting reasonable robust moves that tend to lead to more favorable
options is probably a good objective. The lengths of the simulation
are perhaps too long to expect anything better. Later towards the
pre-middle to middle game it is very critical to play such that the
positions tactical potential is exploited such to secure connections
and eye space, etc. It would seem to me that focusing the highest
concentration of time and number of simulations during this part of
the game might be most advantageous.
It would be interesting for someone with a decent MC player to do an
experiment like this with one version concentrating highest number of
simulations in the opening and one concentrating in the middle game,
but otherwise equal and see which version wins more often.
My experience with Valkyria is that most time must be allocated towards early
moves. If you make a mistake on 9x9 it is very hard to come back. MC/UCT
programs such as MoGo are very good at defending a won position. Therefore it
is important to get a won position as early as possible. The longer it thinks
the better it plays. In the opening it always critical to find the best move -
but later on games are often either won or lost so saving time for those
positions are not so important.
Valkyria saves time in the opening by using an opening library, but as soon as
it leaves the library it spends a lot of time on the first move. Moves it
spends a lot of time on is also stored in the library. And later on I might
correct moves that was played in lost hand myself. I am actually rarely
satisfied with the opening moves of Valkyria. It needs more time for those
moves...
-Magnus
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