Hi!

I found a video with some game analysis by Yilun Yang 7p from the american Go congress 2019 where he uses the words (Video 17:07 min) like above: "If we are weaker: extend - if we are stronger: hane", witch sounds very logical to me. Unfortunately some minutes later (22:30 at the video) he said the opposite: "Black is weaker, so he should have". Im confused.

Is there a proverb like this?

Thanks a lot!

Here is the video: https://www.youtube.com/watch?v=2beB5GsJFBc

The old (pre-AI) proverbs about the hane are based on one's skills and desire to fight with those skills. Extending is safe but gives up momentum, sente, and possibly a lot of influence. The hane is aggressive and can lead to greater losses or, of course, a gain in both momentum and influence. One must know what to do with momentum and influence or the hane easily becomes an unanticipated, and likely quite expensive, sacrifice.

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I think he misspoke. Yang had just compared the two double approach stones and said that the one on the top side is stronger because of other friendly stones nearby. (For those who have not looked at the video, Black has played a double keima approach to a 4-4 stone, and Yang is discussing how White should respond.) If White plays the jump attachment against the top side approach stone, Yang say that it is stronger, so hane. Then soon after he says that if White plays the jump attachment against the right side approach stone, it is weaker, so hane. In fact, the hane is the default play against the jump attachment.



There are two proverbs, each of which has exceptions. For the top right corner, the proverb is this:

Hane against an attachment.

See https://senseis.xmp.net/?RespondToAttachmentWithHane

The hane is pretty much the default, but it usually provokes a strengthening play by the opponent, and it leaves a cutting point behind. So sometimes the simple stretch is better.

In the top left corner is this:

Don't look, hane at the head of two stones.

See https://senseis.xmp.net/?HaneAtTheHeadOfTwoStones

In the West people usually leave out the "Don't look", but exceptions to this one are uncommon. The joseki in the top left corner is an exception. The problem with the hane is the cutting point. In this case Yang is saying that Black is too weak to leave the cutting point.

While they both involve a hane, these are really two different situations. While reviewing the game, Yang does not point that out, but in a book about tesuji or joseki or proverbs, I'm sure that he would make that obvious.

The hane from a single stone is often less of a concern than the hane from two stones. The reason is that if the opponent cuts, it is in general easier to throw away one stone than two.

Both proverbs have exceptions, but when to extend rather than hane can be a subtle question.

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