I have often wondered what makes the difference between pros.

I had a surprising little insight today. Shusai began a commentary on an old game, as in the lower left below, by saying, "Playing simply kosumi with Black 9 is disadvantageous in tewari terms."



On a hunch I checked his games. He played this "Shusaku kosumi" often as a young player but after he became Honinbo he never played it once. Seems (a) he discovered something valuable, and (b) he put his faith in tewari.

Analysing this in tewari terms seems difficult unless we simply make the case that if Black plays 9 first and White approaches as in the game, Black would not play 1 but would go into the 3-3 point.

Regrettably he did not say what he would have played for 9 here, but the knight's move seems likely.

Funny. My instinct is to continue with a two space jump in lower right corner to assure white gets a low position on the bottom. Then the kosumi in the lower left loses one of its purposes, and black might even locally choose tenuki to counter pincer (a) or, less likely, play in upper left (b). I wouldn't dream of the kosumi (c), so maybe tewari shows us the best continuation might be tenuki?

Click Here To Show Diagram Code

[go]$$B
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . b , O . . . . , . . . . X , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . a . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . c . . . . . . . . . 1 . . X . . |
$$ | . . X , . . . . . , . . . . . , . . . |
$$ | . . . . O . . . . . . . 2 . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

(Yes I know, white might not play 2 for this reason, but then black should still get some compensation while keeping c in reserve, if needed.)

_________________
- Brady
Want to see videos of low-dan mistakes and what to learn from them? Brady's Blunders

Good point. I was on auto-pilot, thinking of tewari in local terms. Which is probably correct, as it happens, but still this position after White 8 was already known and Black has tried, in order, L3, R11, J3 and H3. It even occurred as late as 1926 and Hashimoto Utaro no less played H3.

Well, how often did he play Black as Honinbo? My impression is that this kosumi was seldom played as White, by anybody. After 1850, I mean.

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

White has played this kosumi much more often since 1850 than before, and it is still alive and kicking today (about 3,000 GoGoD games). Komi may be a factor, but even while Shusai was Honinbo, Go Seigen was playing it as White, no komi.

Clearly not everyone agreed with Shusai, and/or there may be stylistic features. But note he didn't keep his view secret.

You mean none of these geniuses found my winning move?

_________________
- Brady
Want to see videos of low-dan mistakes and what to learn from them? Brady's Blunders

Thanks, John.

What I read when I was learning go, maybe by Takagawa, I'm not sure, was that the kosumi was considered slow, but fine for Black in a no komi game. No mention of tewari, as I recall.

I wonder, what's the White/Black ratio in no komi games after 1850?

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

Is it uncommon for professionals to constantly be striving for the best move, even if it means forsaking moves they have thought were perfectly good in the past? That seems like a fairly natural progression to me, but perhaps that is not the norm when one's livelihood is on the line.

No.

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

Then what about this anecdote gives insight into Shusai's separation from his peers? It certainly shows his own growth in strength, and it is a valuable observation for that reason alone, but I'm struggling to see what he did differently from other professionals of the time.

Perhaps the key is in tewari analysis. I briefly searched on Sensei's library and saw that it was invented in the late 1600s. Was it not widely used in the early 20th century, such that Shusai's reliance upon it was remarkable?

The prototypical examples of tewari are clear cut. One player ends up with an extra, wasted play, for instance. But many potential applications of tewari involve judgement. In this case, for instance, I agree with John's suggestion that Shusai was considering the hypothetical first play to be on the 5-4, and then after an approach on the 3-5, the reply on the 3-3 would be better than the reply on the 4-3. So far, so good. But is the fact that that is better than the position after the kosumi because the kosumi is inferior, or because the 3-5 approach to the 5-4 is inferior?

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

So Shusai's genius is in applying a well-known analysis technique to a situation where it would not normally be used, using that analysis to determine a certain move is bad, and then demonstrating confidence in his judgment by never playing that move again. Thanks for helping me understand, Bill.

In the end, this does tell me something about top players: they are willing to forge their own way, no matter what what the received wisdom of the ages might say. And, perhaps more importantly, they trust their judgment and are willing to act on it, whether in a game or while evaluating a position. (Are they strong because they trust their judgment or do they trust their judgment because they are strong? Probably a bit of both.)

As for which move is the mistake in your variation, that's still beyond my ability to say. Shusai might know...

One reason that I follow the proverb and discourage beginners from memorizing joseki is that in the end you must rely upon your own judgement, so you'd best start developing it now.

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.