(Author: aLegendWai (9k? KGS) : - )
It is a trick play, hoping mistakes from B.
Even if B respond correctly, W will not lose anything more from this trick play locally (although W remains to lose by 1 point X-X). You are reminded that it is the last endgame.
Bob Myers: This is not a "trick play" in the "hamete" sense. This is either just a bad move, which needs to be punished. This page should probably be moved from the "Hamete" section and placed in a new section called "Dumb tricks that might work if your opponent is a double-digit kyu player."
A ko fight over for one point. Locally speaking, B can only pass (there's no ko threat in the diagram!) and W wins the ko.
We know B should not be too timid.
B should fight instead of retreat.
But the question is how B should fight?
B is happy to keep extending. When B extends by 1 stone, W keeps losing 2 points ().
Note: The loss of 1-point (at second line) occurs once B plays at . Afterward the 1-point loss keeps moving by 1 point to the right. So this loss is not counted to the loss of further B extension.
After extension, how W should respond then?
W has to grasp the only chance to play at the first line now. It is no longer possible if you miss that chance (due to the lack of the support of at the third line. This keeps B's invasion group 1 liberty).
aLegendWai (9k? KGS): Simply they gets the same point/score difference.
Bill: They get the same score only at the end of the game. Normally this position will be played out before that. The throw-in is never better, almost always worse.
Bill: My comment is out of place in this problem. I wrote it about something else. If you want to refer to that discussion, fine. But make a reference or link, not a copy that destroys context. Please.
I think that Chris Schack's question below shows why it is good to link instead of just copying. The link keeps everything together. With copies you can get almost identical discussions that differ from each other.
aLegendWai (9k? KGS): Hi, Bill. First it is out of concern in the illustration because we just concern locally (ie consider what is given in the diagram). In this sense, both plays are definitely equal as far as I know.
Even if we think globally, I'm afraid we cannot be so sure to say throw-in is never better if you consider trickiness as a valid point. It is harder to deal with throw-in comparing with the normal hane.
In a real game, players not only play the standard moves, but also trick move. Very often if the opponent doesn't get trapped, it will turn out to get a better result. Although trick moves are usually not the optimal play, we can still see trick moves in the game.
So the trick play - throw-in is still worthwhile depending on situation (although it is never tricky to advanced players like you ^^).
I think you assume both parties must play perfectly. In this case, throw-in is not preferred then.
The following illustrate why they get the same point/score difference. (Credits: HolIgor)
HolIgor: Black has 4 points while white has 3 points. The score is -1. Black ended in gote.
aLegendWai (9k? KGS) Note: -1 is caluclated by the formula (W-B = 3-4). The reverse is possible, ie B-W = 4-3 = +1. It makes no difference to the result. The +/- simply denotes:
HolIgor: Black will have to defend before connecting the ko. The score is 0. Black has 2 points plus 1 captured; white has 3 points. There is yet another possible point for white in the ko. So, white has already won a point and can add another.
Yet, this is gote for white.
ChrisSchack: Would it be a good idea for W to play a here immediately following?
aLegendWai (9k? KGS): Note:
HolIgor: Black has 2 points + 2 captured. White has 1 point + 2 captured. The score is -1. Black ended in gote. This is the same as the normal hane.