InvincibleTheGamesOfShusaku/Game 25 analyzed with KataGo

Moves 1 to 10  

The game starts off with a taisha joseki in the lower left.

Moves 11 to 20  

here requires a favorable ladder for Black. I'm leaving out the diagram given in the book to prove this. KataGo thinks this is a 3 point mistake and should have been at A. Prior to that, was a 2 point mistake and should have been at A as well. The book doesn't mention A as a vital point for both.

The book does label as a non-joseki move which costs White. KataGo disagrees and finds only a fractional loss, compared to the book's suggested joseki move B.

Moves 21 to 30  

KataGo thinks is a small mistake (1 point) and should be a hanging connection instead. The hane at the head of two with is too good.

The book then explains why is better than the usual hane:

Diagram 3 in the book  

The book states: "This would be the usual way to make shape but that would give Black an ideal peep at A". KataGo is not considering A and when I played it out, it assesses the peep as a 2 point loss for Black. My interpretation is that Black's peep doesn't really gain anything, since White confirms the eye and the combination of Black's keimas is thin.

Moves 21 to 30  

Back to the game, where White's subsequent move at which "invites a forceful attack by Black. It's an over-extension which becomes the losing move", says the book and it proceeds with an eulogy on Shusaku's ability to punish opponent overplays.

KataGo thinks is the best possible move. The difference with the book's suggestion for White to refrain with a simple one space jump at , is small but nonetheless positive, even after many playouts. Yes, Black can counterattack but KataGo doesn't consider that to be a big problem. On the contrary, it prefers to take it easy with B, after forcing with A. This time A is a good forcing move:

Forcing - 1  

If White answers at here, Black can later grab two stones with A.

Forcing - 2  

If here, White has bad aji around A.

Moves 31 to 40  

The cross cut and its subsequent moves - are all normal according to KataGo. The book doesn't explain why holds back to a solid extension but KataGo thinks this is a rather big mistake. A one space jump towards A would keep the advantage around 4 points, while now White can move faster, towards B, and the difference shrinks to 2 points.

KataGo also doesn't like all that much, my interpretation being that it strenghtens White unnecessarily and destroying the shape is not that valuable.

The book calls unnecessary and KataGo thinks it's a 2 point mistake, my interpretation being that it reduces a liberty.

Moves 41 to 50  

After in the previous figure, probably shows why was so bad, as it loses tempo.

The book says " is the kind of shape professionals dream about. It leads out Black's sole weak group while amply maintaining the pressure on White's two weak groups. Black seems to be heading for a comfortable win" and puts the blame again on White's losing move at . KataGo sticks with an evaluation of B+3 which is not to blame on (a blue move) but on Black's first move advantage which he has already half squandered.

On the book says: "... is the instinctive fighting move but here it is welcomed by the opponent". KataGo seems to agree on the following diagram being better:

Diagram 9 in the book  

In fact this would reduce the gap to below 2 points, far from the comfortable lead the commentary suggests.

Moves 51 to 60  

While the book glances over it, KataGo finds at fault and suggests cutting on the other side. This is interesting:

Sacrifice - 1  

Sacrificing two stones like this, sets up a squeeze. After at A, White can capture the original cutting stones or extend at the side. The interesting question is: what if Black avoids the squeeze?

Sacrifice - 2  

KataGo evaluates this as a profitable swap for White. I can't read the pro commentary's mind but I assume it would evaluate the loss of the center stones as unbearable for White.

Moves 51 to 60  

Back to the game: the book calls "the losing move if that wasn't already claimed before". KataGo doesn't think about but, when played, doesn't consider it that bad. Next the book criticizes as it seems to attack Black's shape but does so in vain. KataGo doesn't think it's worse than the book's suggestion to defend the top at A instead.

Moves 61 to 70  

The book calls logical but hails Shusaku's flexibility to drop the pivotal stones and make good shape at . "The game is over".

KataGo seems to agree maintains the lead in a simple way but not distinctively better than connecting at A, Black's lead being 4,5 points in both cases. Such a lead in the late middle game is game over indeed at the pro level but it's still a reduction from the initial advantage.

The book calls a declaration of victory: Shusaku is allegedly so far ahead that he can afford soft moves like this one. KataGo agrees it is soft and a White cut & connect at A would reduce Black's lead to 2,5 points.

As for , this is a "dubious move" in the book. KataGo thinks it's the best move after cutting and connecting in the center again.

Moves 71 to 80  

So, when Black connects at , the game - in my opinion - is simplified. By the game is still a 5-pointer for Black and we're approaching the end game.

In conclusion, the commentary in the book, as said, hardly correlates with KataGo's analysis. While such analysis requires much more time and playouts, force feeding the game moves and the variations, the times when I did so did not reveal a sudden shift in KataGo's evaluation towards the commentary's. Vice versa we can't retrospectively find out what the commentator(s) would say to KataGo's main issues with the game.

With this comparison, I don't want to devaluate the commentary, let alone the great book, but rather point out that commentaries like these might reflect biases with the commentator at the time and must be taken with the necessary caution - just like KataGo's evaluations.