Here is the local sequence of play in game 1 starting with White 144.
- Click Here To Show Diagram Code
[go]$$Wcm44 Zen loses 2 points locally
$$ ---------------------------------------
$$ | . . O X b . 5 W . 2 1 3 6 . . . . . . |
$$ | . O . O X . W X X X X O X . . X X . . |
$$ | . . O . X . W W X . O O 4 X . O . O . |
$$ | . O . , X . . W X X O X . X O , O . . |
$$ | . X O O X . . a O O X X . X . O X . . |
$$ | . X X X O . . . O X O . . . . O X . . |
$$ | . . . . . . . . . . . O . O O O X . . |
$$ | . . . . . . . . . . . . O X . X X . . |
$$ | . . . . X . . . O . . . O X . X . . . |
$$ | . . . , O X X . O X . O X X O X O . . |
$$ | . . X X X O X . . . . O X . . O . . . |
$$ | . . O . O O O X X X . X X O . . . . . |
$$ | . . X O . X X O O X . . X . . O O . . |
$$ | . . X . . . O . . O O . O O O X X X . |
$$ | . . X O . . . . . . . . . . X X . O O |
$$ | . . X O . . . . . , . . . . X O O O X |
$$ | . . O . . O . . . . . O . . X O . X X |
$$ | . . . . . . . . . . . . . . X O O X . |
$$ | . . . . . . . . . . . . . . . . . X . |
$$ ---------------------------------------[/go]
OC, White loses the semeai. But he also unnecessarily loses the
stone.
at 46 also allows White to take his kikashi in sente, but loses only 5 stones instead of 6.
White has a cutting point at "a", and
protects the
stones by the possibility of connecting them with a play at "b".
Why would a Monte Carlo based bot pick
over
. I don't know, it may have been a random error, but here is a hypothesis.
- Click Here To Show Diagram Code
[go]$$Wc Fill the outside liberty
$$ ---------------------------------------
$$ | . . O X . . . O 3 . 4 1 . . . . . . . |
$$ | . O . O X . O X X X X O X . . X X . . |
$$ | . . O . X . O O X . O O 2 X . O . O . |
$$ | . O . , X . . O X X O X . X O , O . . |
$$ | . X O O X . . . O O X X . X . O X . . |
$$ | . X X X O . . . O X O . . . . O X . . |
$$ | . . . . . . . . . . . O . O O O X . . |
$$ | . . . . . . . . . . . . O X . X X . . |
$$ | . . . . X . . . O . . . O X . X . . . |
$$ | . . . , O X X . O X . O X X O X O . . |
$$ | . . X X X O X . . . . O X . . O . . . |
$$ | . . O . O O O X X X . X X O . . . . . |
$$ | . . X O . X X O O X . . X . . O O . . |
$$ | . . X . . . O . . O O . O O O X X X . |
$$ | . . X O . . . . . . . . . . X X . O O |
$$ | . . X O . . . . . , . . . . X O O O X |
$$ | . . O . . O . . . . . O . . X O . X X |
$$ | . . . . . . . . . . . . . . X O O X . |
$$ | . . . . . . . . . . . . . . . . . X . |
$$ ---------------------------------------[/go]
After the descent,
,
is normal play, winning the semeai.
- Click Here To Show Diagram Code
[go]$$Wc Do not fill the outside liberty
$$ ---------------------------------------
$$ | . . O X . . . O 3 . 1 . . . . . . . . |
$$ | . O . O X . O X X X X O X . . X X . . |
$$ | . . O . X . O O X . O O 2 X . O . O . |
$$ | . O . , X . . O X X O X . X O , O . . |
$$ | . X O O X . . . O O X X . X . O X . . |
$$ | . X X X O . . . O X O . . . . O X . . |
$$ | . . . . . . . . . . . O . O O O X . . |
$$ | . . . . . . . . . . . . O X . X X . . |
$$ | . . . . X . . . O . . . O X . X . . . |
$$ | . . . , O X X . O X . O X X O X O . . |
$$ | . . X X X O X . . . . O X . . O . . . |
$$ | . . O . O O O X X X . X X O . . . . . |
$$ | . . X O . X X O O X . . X . . O O . . |
$$ | . . X . . . O . . O O . O O O X X X . |
$$ | . . X O . . . . . . . . . . X X . O O |
$$ | . . X O . . . . . , . . . . X O O O X |
$$ | . . O . . O . . . . . O . . X O . X X |
$$ | . . . . . . . . . . . . . . X O O X . |
$$ | . . . . . . . . . . . . . . . . . X . |
$$ ---------------------------------------[/go]
However, after the hane, filling the outside liberty is a mistake, allowing White to win the semeai. I suspect that in Monte Carlo randomized playouts, Black will lose the semeai more often after the hane than after the descent and thus the program will assign the hane a higher probability of winning the game. I do not think that this error would occur if the tree search were confined locally, but it is global. Claims that Monte Carlo bots correctly assess the probability of winning the game must be taken with a grain of salt.