declaration of victory
Tamsin: Have you ever been leading by a large amount and made an underplay that fortifies your position, often unnecessarily, with the intention of signalling to the opponent that further fighting is futile? I call such a play a Declaration of Victory, because it is a move that says "Do your worst, from now on I don't need to stretch myself anymore to win this game!"
A declaration need not necessarily be a weak move. How about this definition:
A declaration (of victory) is an underplay that removes the most likely do-or-die effort when one is well ahead. It may lose points compared with ordinary maximal play, but it can be a good practical choice for winning a won game.
Example:
This is game 6 from the 1992 Honinbo match between Kobayashi Koichi and Cho Chikun. Kobayashi holds the White stones, and it is his turn.
According to the commentary in Tournament Go 1992, White has a very small lead. Here, White should, then, continue playing hard to convert his lead into victory. However, Kobayashi did the opposite. On his next move (62) and four moves later (66) he made underplays that, although intended to remove any comeback-chances, actually handed the initiative over to Cho, who was then able to win.
1 and 5 are the culprits. They might be called a declaration in the sense that White has decided to sit on his lead rather than continue fighting. And yet this was the point Cho started to come back into the game.
At the amateur level, a declaration would be similar in principle, but more crude in its manner: it would be a big, but slack move, that hints the player thinks he or she has already done enough to win, and can now win simply by sitting back and defending, come what may.
And, to paraphrase a legend, here is what White could have won...
Here, White should have descended to 5. Now, Black can turn at 6, which is very large, but this is still outweighed by the thinness of the top left. In other words, what was played was purely defensive, declaring that "what I have is enough", but this 5 would have continued fighting positively, seeking ways to get more instead of trying to sit back.
fractic: I found a nice example on goproblems. GP
Tamsin: Hi, thanks for this. I looked at this amusing example. It is not so much a declaration of victory as holding a Victory Parade on White's front lawn, LOL!
Andreas Teckentrup: that move was looking very strange, but is actually remove some dangerous cutting aji. Its a rather famous move, ive seen it analyzed in a Japanese go book too.
fractic: I can't find any way to cut at all. And even if there is such a way there surely has to be a more active way to defend against it.