[Computer-go] Anomalies in MCTS

"Ingo Althöfer" 3-Hirn-Verlag at gmx.de
Mon Feb 4 05:38:01 PST 2013

Hi Cameron, hi Jonas,

thanks for your feedback.

> You might try some of the RAVE counter-examples, such as the following
> position from Martin Mueller (White to move):
> http://www.cameronius.com/research/go-rave-blunder-1.pdf 
> It's a seki position in which FUEGO chooses the correct move B2 without
> RAVE, but the incorrect move D9 with RAVE enabled.

I translated this position in sgf. Programmers can find it at
and may try with their bots.

> Not sure whether this will translate to the bizarre MC behaviour that
> you're looking for, but it's worth a shot...

Here is the first little game where we found the anomaly of pure MC.


DSR stand for "Double Step Race".
The important part is in the upper lane. Each player (White and Black)
has one stone there. Stones move to the right, either single or double
steps. The first to reach his goal square (with the frame in white and
black, respectively) is winner.
In the lower part each player has one more stone and 16 black holes
around it. This stone may jump in one of the black holes and will not
return from there.

Every player with (human) intelligence will never move the lower stone,
but only run with his upper guy. But MC(8) gets more than 50 % against
MC(16) under fair conditions (each player gets the first move in
half of the games).

Regards, Ingo.

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