InvincibleTheGamesOfShusaku/Game 26 analyzed with KataGo

The third castle game is also one against Sakaguchi Sentoku. This time the commentary is adapted from one by Ishida Yoshio. Like the previous one the commentary makes strong claims which don't hold up against AI analysis, or we need more playouts, or AI is wrong and Ishida is right.

Moves 1 to 10  

We now know that opening on a 3-5 point like W2 is not putting enough emphasis on the corner according to AI. Likewise, a pincer like B5 would today never precede a move in an open corner.

Moves 11 to 20  

B13 gets applause by Ishida, who says the three space pincer works excellent here. KataGo is less enthusiastic. Instead it wants to poke at White's shape at A. The open corner is also among the better options.

W14 used to be joseki but nowadays has disappeared. Instead one invariably answers such a pincer at B19.

Moves 21 to 30  

B23 inducing B25 gets more applause by Ishida and I agree Black's stones are flowing naturally. So much that KataGo wants White to play at the right side instead and sacrifice the top.

Moves 31 to 40  

A splitting move like B33 today is regarded as a little passive and shoulder hits like A are in fashion.

W36 is allowing Black to swallow the marked stone naturally. AI prefers activating that stone with W36 at B instead, so as to split Black.

Moves 41 to 50  

W44 gets a bit of explanation

White 44 comment  

Ishida comments that W1 here would be met with B2, hence futile. Still, KataGo thinks this is the right move. Without underestimating the pros, the follow-up is quite surprising.


W1 steals Black's base. If B2 at W3 ...


...Black is separated.

Moves 51 to 60  

KataGo doesn't second B51. It agrees with Ishida that W56 is a well timed leaning maneuver.

Moves 61 to 70  

When B61 captures, KataGo wants to launch the ko at A, rather than settling for the top with W62. Because of the placement at B, White can kill the top if Black doesn't answer, so even a big threat like C can be ignored. Black would have to live at the top, giving White a free connection.

As the book mentions White plays W66 to remove aji but it is too slow.


After W1 for example Black can live at the top but White can then connect underneath and destroy most of the shape Black had gained by winning the ko.

Moves 71 to 80  

W78 is criticied in the book. Ishida thinks White should have played underneath to avoid the game sequence. KataGo thinks W78 is the correct move in this position.

Moves 81 to 90  

The commentary has White running fast into defeat. KataGo on the contrary thinks that by B99 the game is almost even.

With W90 however White loses his grip on the game again.

Keeping up the pressure  

W1 attacks Black's shape while threatening to cut off some stones. After Black takes territory on the left, White can attack Black's dragon. This is more active.

Moves 91 to 100  

White's marked move was taking into account the central balance of power but it allows Black to take the initiative at B93, tackling White's vital point while creating shape for himself.

The book says that by B95, the game is over. KataGo thinks the gap is 2.5 points. And this loss was only suffered over the past few moves, not during the fuseki.

Ishida's final comment "Though this game was not as humiliating for him as the previous one, Sentoku was never given a chance." doesn't correspond to KataGo's assessment throughout.

Endgame considerations  

A quick territorial count indeed gives about 15 points advantage for Black. The reason the game is closer than that must lie in the comparative strength and potential points. Black has particular bad aji at W1 here. White can destroy all the territory here in sente.

White can also make points while attacking Black's top group, starting at A. Since White can keep sente, we can expect the big move B to fall to him.

InvincibleTheGamesOfShusaku/Game 26 analyzed with KataGo last edited by Dieter on November 22, 2023 - 10:49
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