Life In 19x19 :: Negative sente

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Negative sente http://lifein19x19.com/viewtopic.php?f=15&t=16628	Page 1 of 1

Author: Knotwilg [ Tue May 14, 2019 1:52 am ]

Post subject: Negative sente

In my recent study of the endgame I came across an interesting move/concept:

Click Here To Show Diagram Code: [go]$$ Negative sente $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . O X O . . . . X O . . . . . | $$ | . . X O O O X O O O O . . . O O X . . | $$ | . . X X O X O O X O X O O O X , X . . | $$ | . . . X X X X X X O X O X X X . . . . | $$ | . . O O O X . . O X X X O . . . X . . | $$ | . . . . X O X X O X O X O O O O X . . | $$ | . O . X . O O O O X . O O X X O O a . | $$ | . X . X O . . . . . O O X . X X O . . | $$ | . X . X . . . . O . O X X X X O O . . | $$ | . X O . O . . . O X X X O . X X X X . | $$ | . X O . O . . O X O . . a . . . X . X | $$ | . . X O . . . O X . O B . O . X O X . | $$ | . X . X O . . O O X . b . . O O O O . | $$ | . O . . . . O O X O O O W O X X X O . | $$ | . . O O O d X O X X O X O X . , . X . | $$ | . X X X O X . O X . X . X X . X X X . | $$ | . O O O X . X X . X X X . O X . . . . | $$ | . . . c . X . . X . . . . . . X . . . | $$ ---------------------------------------[/go]

White ''a'' saves a stone while threatening to cut off a stone. It's a mild form of sente: the follow-up of cutting of the marked stone is bigger (swing 6, tally 2) than the move itself (swing 2+, tally 2).

Black ''b'' threatens to cut off a whole group and change the outlook of the game. It prevents White from making 1 point there. It's a severe form of sente, while it's not very urgent as it only "gains" 1 point.

However, ''a'' and ''b'' are related to each other.

Click Here To Show Diagram Code: [go]$$ Negative sente $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . O X O . . . . X O . . . . . | $$ | . . X O O O X O O O O . . . O O X . . | $$ | . . X X O X O O X O X O O O X , X . . | $$ | . . . X X X X X X O X O X X X . . . . | $$ | . . O O O X . . O X X X O . . . X . . | $$ | . . . . X O X X O X O X O O O O X . . | $$ | . O . X . O O O O X . O O X X O O a . | $$ | . X . X O . . . . . O O X . X X O . . | $$ | . X . X . . . . O . O X X X X O O . . | $$ | . X O . O . . . O X X X O . X X X X . | $$ | . X O . O . . O X O . 3 2 . . . X . X | $$ | . . X O . . . O X . O B . O . X O X . | $$ | . X . X O . . O O X 4 1 . . O O O O . | $$ | . O . . . . O O X O O O W O X X X O . | $$ | . . O O O d X O X X O X O X . , . X . | $$ | . X X X O X . O X . X . X X . X X X . | $$ | . O O O X . X X . X X X . O X . . . . | $$ | . . . c . X . . X . . . . . . X . . . | $$ ---------------------------------------[/go]

If Black plays his "sente" move :b1:

then White can postpone the direct answer and play :w2:

first to force :b3:

and then respond. So, playing :b1:

not only wastes a ko threat, more importantly it increases the value of :w2:

prompting White to play there and therefore losing the opportunity for Black to play there himself (and gain 2 points).

This makes :b1:

so unlikely a move that it doesn't "exist" in my opinion. Its existence depends on Black playing at :w2:

: then

becomes Black's prerogative.

What do you think?

Author:	Uberdude [ Tue May 14, 2019 2:18 am ]
Post subject:	Re: Negative sente
Yes, this kind of not wanting to play (or at least having downsides) a sente move because it gives your opponent a kikashi once you've declared you want it can happen not only in endgame, the first example that comes to mind is the counter peep to a peep technique to make the peeping stone heavy, e.g. a in viewtopic.php?p=235972#p235972. Moves like 1 can be good/annoy opponents if played as a ko threat: if white plays 2 for the good endgame it gives black an extra threat (we assume black would not connect directly but retake the ko because the ko is bigger than white 3 gobbling a few stones) so white probably just defends at 4 and then black might (but probably not) get the next move in the area at 2 in endgame (it's only a small threat for white in a big middlegame ko).

Author:	John Fairbairn [ Tue May 14, 2019 4:48 am ]
Post subject:	Re: Negative sente
Quote: If Black plays his "sente" move I think you are creating problems for yourself by misusing "sente" - as you are evidently aware from your addition of quotes. There's a deeper problem, though. We all say "forcing moves" for kikashi, but that carries within it the idea of compulsion, and so "sente" comes to mind. But the real meaning of kikashi is simply that it is a move that has an effect (or a "benefit" if you prefer the alternative term uchidoku). A good way to think of it, perhaps, is simply as a "useful interpolation" as that doesn't bring in the idea of sente in a gross way. Furthermore, the criterion for being able to call it a kikashi then more evidently becomes whether you can demonstrate it does have a "useful" effect (as opposed to having simply a "forcing" effect). Here the effect, as you demonstrate, is not useful, so it is not a true kikashi move. If Black plays first move in one corner, it almost demands White plays a move in another empty corner. But we don't say Black had sente (even if he did!). The same applies, I think, to kikashi. Sente is about having the initiative: CAUSE-and-effect. Kikashi is about cause-and-EFFECT.

Author:	Knotwilg [ Tue May 14, 2019 7:12 am ]
Post subject:	Re: Negative sente
John Fairbairn wrote: I think you are creating problems for yourself by misusing "sente" - as you are evidently aware from your addition of quotes. Well, I've grown so frustrated with guessing what Japanese terms mean (I mostly get to know what they don't mean) that I'm trying to avoid them altogether, at least in my own written thoughts. When communicating with others, my own invented terms may not be very helpful, so I resolve to terms like "sente", knowing that it may be scorned. In my written thoughts https://senseis.xmp.net/?DieterVerhofst ... calEndgame I differentiate between the following endgame concepts: - the dominant move, i.e. the one single move on the board the opponent must respond to or they will lose the game (if there is one) - disruptive border plays, i.e. a border play which, if unanswered, disrupts the assumptions of the endgame, either the status of a group or the rough shape of a territory - a player's prerogative, i.e. a move which, if unanswered, will make a larger gain than the move itself These are, from very narrow to broad, what I've seen labelled as "sente" but I avoid the term, since the discussions on what it means deter from the concepts I want to use when thinking and discussing the (end)game. As for kikashi, I've given up on that one even much longer ago. Quote: If Black plays first move in one corner, it almost demands White plays a move in another empty corner. But we don't say Black had sente (even if he did!). The same applies, I think, to kikashi. Sente is about having the initiative: CAUSE-and-effect. Kikashi is about cause-and-EFFECT. I'm sure you are totally sincere in these statements, but to me they are esoteric. I don't think you imply that sente equates with the mere rule of alternating play (after I have played, it's your turn, so you have sente), nor that kikashi equates with playing a move (I have played, you have responded in a certain way, thereby commiting yourself to a choice, so you have been kikashi'd). You've gone to great lengths explaining these terms, so consider me a hopeless case.

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