[Pachi] Analyzing Pachi games

Evan Daniel evanbd at gmail.com
Wed Apr 20 01:32:21 CEST 2016

So I'm just starting to explore the Pachi code base, and trying to
develop an understanding of how the engine thinks. Any tips on what I
should explore, or what I should do to analyze a game Pachi played?

(Also, it's a neat engine, and I like the modularity, flexibility,
available options, etc.)

A very basic question: what sorts of win rates should I interpret as
"ahead" "even" "behind" " farahead" etc.?

For example, I played the attached game against Pachi. It was running
on my slightly older desktop, at ~ 20k playouts/move. (Default timing
settings? I just fired up GoGui.) It seemed like even fairly late into
the game, Pachi didn't realize how much trouble it was in (winrate >

I played the game without the pattern files (
http://pachi.or.cz/pat/gogod-handikgspachi-iter/ ), but they don't
seem to make much difference. (See attached analyse-sgf.pl output.)

So, if I wanted to understand what went wrong, what would be a good
starting point? (Opinions about what went wrong are also welcome, but
I'm more curious about the methods you'd suggest using than the
specific answer.)


Evan Daniel
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