Quoting Sylvain Gelly <[EMAIL PROTECTED]>:
Hi Darren,
After white (mogo) H2, MoGo was estimating 74%, and expecting:
H2 G1 H3 B1 A1 B3 H1 F8 B5 H4
Then black played H3, and estimation increased to 81%, white B3 and
expecting:
B3 B1 A1 B4 C5 C4 A3 C6 B6 B5
This sequence is a disaster for Mogo because the position after B5 is
trivially
lost.
But the error is white A3 in this variation. Normally making an eye is good in
the semeai, and in random playouts it is a winning move in this position. But
here it gives black time to win the semeai against the stones which are not
protected by the eye.
B3 B1 A1 B4 C5 C4 >B5< instead captures the black stones right away if
I am not
blind to something. [Valkyria wants to play C6 instead of C5 which also seems
to win easily]
Since the main line was very strongly refuted very deep I guess MOGO
had no time
finding the better variation at the 7th ply and thus played the second
best move
at the root. G3 makes it much harder for black to capture the white
stones, but
now we have two kos and white need only win one to believe its stones
are safe.
If white is lost now it has to search very deep to see it for sure.
Still the fight turns to the upper side after white lives and now white has a
chance to live but plays A7 at move 50, but if white plays C9 for life it is
very close, but if my analysis is correct then black wins with 0.5 after
threatening a seki in the corner. [Valkyria misunderstands this position
completely because of the seki in the corner so I could not use it.]
The fight after this is also very far from trivial.
Mogo fills in its own liberties in order to kill the group of Steenvreter, but
dies and loose the semeai. It is possible for Mogo to live by throwing in with
A9 but then Black will win with a kofight which involves white trying
to invade
the upper right group as kothreats. This fight was a matter of a single
liberty
as well...
So Mogo did make a mistake because the main variation was suddenly strongly
refuted although the first move is ok. The move played led to a really
long and
hard fight where I cannot tell for sure if there was a second mistake.
Maybe it
is a close win for black with perfect play.
Actually during pondering MoGo realized that it was lost then, because
black played the expected move (B1), but the estimation was then <
50%.
So with more time (few time was left at this point) it would have
realized earlier.
However I wonder where was the mistake: H2, B3 or much before, i.e.
already before H2 white was dead?
I am sorry, if it is trivial mistake and the position is obvious :-/
Sylvain
To me almost all positions after the opening is far from trivial in this game.
-Magnus
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