InvincibleTheGamesOfShusaku/Game 34 analyzed with KataGo

Moves 89 to 90  

Black has sacrificed the upper left in return for central thickness. He has also secured a large territory on the lower side. White has a decent lower right corner and has expanded it towards the right side, while Black has staked out the upper right. Commentator Ishida Yoshio reckons that "Shusaku must have calculated that he could do well enough in the center to win." Before that Ishida acknowledges White has the potential of capturing two stones in the bottom left with A.

KataGo evaluates the cap of to lose a little, making the game jigo. Its preferred moves to maintain a small lead are the more severe shoulder hit at B, the surrounding move of C or the attachment at D.

For White, it suggests making the forcing exchange at A, without capturing the stones yet, and then play the forcing sequence which Hayashi starts at .

kmr - I think this KataGo evaluation of this postion is nice proof that humans overstimate usually value of moyo, or maybe that its very hard to deal with such a moyos for humans. I feel like most games of Shusaku with big moyo KataGo will evaluate critical position vastly different of what humans say. Some time ago, i made brief analyze with LZ of Shusaku-Hakuei (1961 Castle Game, W+14), and when commentator said that game is over and pointed losing move, LZ totally disagreed with him. In Invicible, some games were commented by GoSeigen, i wonder if there is significant difference between commenraty agreement by KataGo. I hope it will be, since afterall GoSeigen was meijin in all but name in about 1950-1960.

Moves 91 to 100  

The exchange of - is again a little better for White. Black should have played A instead, KataGo indicates.

At Ishida comments: "Like it or not, White has to accept Black's challenge to a fight in the center". KataGo agrees but the next exchange of - loses the chance to atari at B and represents a first small loss. It would have been better left omitted and focus on connecting to the top or the right side.

Moves 101 to 110  

The real loss and perhaps even the losing move according to KataGo is here, connecting the top left to the other stones. KataGo doesn't consider to be forcing and indeed, the top left lives by virtue of capturing, while the lower group can pick up those two stones any time. Of course is big but it isn't urgent. KataGo advises the following diagram instead:

Active  

After exchanging A for B, White can build up influence at the top as shown, then strike at the shape point C. This threatens converting the center into a potential territory for White. Black could damage the left side with D but it wouldn't hurt as much as the reversal in the center.

The left side damage  

If , White still doesn't have to respond and can threaten to wreck further havoc center and right with . As shown and undoubtedly read by both players, White still wins the capturing race top left, but the bigger point is the resilience of the lower group. According to KataGo, even if Black covers at A, White still doesn't need to respond, which is probably not even to see for immortals like Shusaku. Anyway, B would provide enough health to the group. The damage on the left is small compared to the big prospects White has created in the center.

Moves 111 to 120  

in the previous figure, marked here, was not only badly timed but also badly placed. Black's counterattack at here is severe. White can't push through at A as it would put the center stones into dire straits.

White's link up at is dame while Black has grown his lower side and top sides into the center. When finally responds at A, Black's original 6 to 7 point lead is restored. Now there is no way White can come back from that.

The pro commentators didn't pick up on the slow move at 108 and instead see the course of the game as a confirmation of Shusaku's correct judgment of sacrificing the corner.