Hi!
Pachi has two RAVE/AMAF modes - in one, it counts as RAVE wins only
moves made by the player further down in the tree. In the other, it also
counts in the moves made in the playout phase.
I think most people collect AMAF statistics only from the tree phase,
at least that's what I've been told.
In the past, the "playout AMAF" mode was not performing good at all
for me either. However, recently I have added 3x3 Mogo-like patterns
and now I have made some major tactical improvements to the playout
engine (and it still doesn't even implement that much, e.g. no 2-liberty
tactical moves are made yet, only atari/3x3 pattern handling).
Now, with 400-800 games of 5k playouts against GNUGo --level 10,
I get a jump from 60% to 80% in winrate if I enable AMAF statistics
from playout phase.
One crucial thing that has cost me a lot of time to find is _not_ to
count nakade moves from the playout phase into the AMAF statistics -
just totally ignore nakade moves and take the first owner for AMAF on
that intersection. Nakade apparently adds a lot of noise and largely
annihilates the effect. Properly handling nakade AMAF during the tree
phase is slightly (74+-1.9% vs 78.2+-1.7%) beneficial.
So my guess is, if your playouts are heavy enough in the right way,
this can be a good bonus. On the other hand, by observing play on KGS,
the bot does not seem to be that much stronger, so maybe this has much
larger effect with 5k playouts than in slower games - I need to measure
the difference for higher playout counts as well.
(Note that I also use my playout policy to seed the tree with prior
values (6 wins/losses), so this is does not just supplement this missing
information, somehow.)
P.S.: By now, I should probably find better reference opponent than
gnugo... I wonder if to pick fuego or mogo... ;-) Strength is probably
not _as_ important as the variety of techniques used in order to avoid
selective blindness (that's why I also don't like tuning by self-play),
does anyone have a tip? Or do higher gnugo levels make much strength
difference?
--
Petr "Pasky" Baudis
A lot of people have my books on their bookshelves.
That's the problem, they need to read them. -- Don Knuth
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