Tedomari Exercise 1

   

Source of diagrams: Guo Juan, Teaching Go at different Levels, Nov. 2002, (advice for 1-2dan)
The game is Lee Changho (white) vs Cho Hun-hyun in the 34rd Kuksu final, GoGoD 1990-09-07a.

[Diagram]

Black to play

How to play so as to take the last big point


[Diagram]

Black loses sente

Wrong: Black attacks and takes an extension (too wide anyway),
but White gets sente for the last fuseki moves.

[Diagram]

Black takes the last Fuseki points

Correct: Here it is Black who takes the last Fuseki points.
Afterwards e.g. White a and checking-extension black b could end in a normal Gote sequence for White.

Afterwards (!) circle=black+circle is the move which Black wanted to get and now will get.


The professional advice by Guo Juan is colored by the following analysis using Leela Zero

[Diagram]

Leela's sequence

Black makes shape in the centre and then takes a big point with B9.

[Diagram]

The "good move"

The above recommended move leads to this diagram, which loses 10% with respect to LZ's sequence.

[Diagram]

The "bad" move

The above advised against move B1 elicits the defence of W2, which affects Black's weak group as well, and loses 11% with respect to LZ's preference.



As has been commented by the go community, professional advice is still instructive, even if seemingly refuted by bot analysis. So, while these diagrams paint a different picture, the spirit of the example may still apply.


xela: Note that the details of the analysis will vary with the software and hardware used. I'm unable to replicate the exact results above. I get the same ordering of move values, but not the "big" winrate drops of 10 or more percentage points.

[Diagram]

Black to play

Using Leela Zero network number 242, indeed b is the preferred move, with a winrate of 63.9% when I try it. But a is only a 6.5% drop, whereas c is a 9.3% drop, noticeably if not significantly worse. And all three options still leave black with a winrate above 50%.

On an older LZ network, number 157, there's less difference: b is still preferred on 60.0%, a is 2.7% worse, c is 4.8% worse (compared to b), and in fact d now emerges as a second choice move, nearly as good as a (but with fewer playouts, so more uncertainty on the evaluation).

KataGo (20-block network g104-b20c256-s447913472-d241840887) gives b as 69.0% with black 8.2 points up, d again as practically the same (fewer playouts), a as worse by 4.2% or 2 points, and c as worse by 5.8% or 2.3 points.

In all three cases the message is the same even if the details differ a little: the "correct" move isn't best according to the bots (although still good enough to win), and they throw out another option that wasn't mentioned in the human analysis.


This is a copy of the living page "Tedomari Exercise 1" at Sensei's Library.
(OC) 2024 the Authors, published under the OpenContent License V1.0.
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