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Ko Threat Playing Order
Path: KoFighting   · Prev: BasicKofightExample   · Next: LopsidedKos
    Keywords: Ko

Normally, you have several ko-threats at your disposal, the order in which they are played is important. Past discussions on the newsgroup seem to indicate that you should play a threat that is larger than the value of the ko, but that you should save your biggest threats for last.

I.e. if the ko is worth 17 points, and you have threats of 18, 25 and 27 points value, play the 18 points first, then the 25 points etc.

The reason for this is that later in the game, a bigger ko may come up which may require bigger threats.

However, you should always play ko threats which are bigger than the ko.

HolIgor: the last statement is not absolute. Get as much as you can if the ko fight cannot be avoided. Avoid ko fights if you can't gain by them.

Dieter: Neither is the first. Suppose I'm 3 points behind and the game reaches its end. My opponent plays a ko worth 3 points. I have a threat worth 4 points and one worth 6 points. He has none. If I play the 4-threat he connects and wins by 2 points. If I play the 6-threat he either connects and it's jigo, or he answers, I take the ko, he passes and I connect: jigo again.

BillSpight: Factors to consider include:

  • 1) Size of threat.

Threats so big that they must be answered are primary threats. Smaller threats that do not have to be answered and are costly to ignore are secondary threats. Even smaller threats that are not costly to ignore but prevent loss if ignored are tertiary threats. Sometimes miai pairs can function as tertiary threats. These are virtual threats.
The komaster may answer secondary or tertiary threats if he has enough primary threats.
In general, the komaster may play any primary threat. The koloser may play any threat at least as large as the largest threat that the komaster should ignore.

  • 2) Whether a ko threat is a double threat.

Some primary ko threats are miai, and may be played by either player. In general, they should be played as soon as the ko fight begins, or in preparation for the fight, to prevent the opponent from playing them.

  • 3) Whether a ko threat is a losing threat.

Some primary ko threats are costly to play. In general they should be played as late as possible.

Other kos may exist on the board, or may arise later, or may threaten to arise. In general, ko threats with larger reverse sente should be played early, since they will disappear naturally earlier in the play if they remain after the ko is decided than threats with smaller reverse sente.

With hyperactive kos one player, instead of winning the ko, may make a play that makes the ko hotter. (With an approach ko she may be forced to play an approach move before she can win the ko.) In general players should save their large threats for the later stages of such kos, after they have become hotter, and play their small threats early.

  • 6) Psychology.

Technically the smallest threat you can play is one such that it makes no difference whether your opponent ignores it or not (if such a threat exists). If your opponent answers a smaller play or ignores a larger play, it is usually an error. You are more likely to induce an error by making plays of around that size early. On the other hand, you are more likely to make an error if you try that tactic, as well. ;-)


Charles Matthews

Or you can read on for more theoretical discussion ...

As far as order of playing threats is concerned, local threats behave somewhat like threats of very high value (say 250). It isn't true that you ought to play high-value threats first.

One of the reasons for that is that you prefer to save them for a later, more important ko. That reason is no good as applied to local threats - you could put it the other way round, that you prefer to finish all the local threats you have before the ko is over.

There is another reason for delaying high-value threats, which is that they may be loss-making threats. Now this certainly may also apply to local threats. They can lose points, either for sure, or if you are anyway going to lose the ko and they make the loss worse. They may also be aji keshi, or throw away liberties or create cutting points, or just in some way have an adverse effect that has to be balanced against their possible gainful effect on the ko fight.

I can certainly show an example from a pro game where one side delays using local threats until the final stages of a ko. I think you can explain that as a probing mechanism: you can be completely sure that local threats enable you to retake the ko. You have that information, you in some way want to test the opponent's approach to fighting the ko (for example, will she start using loss-making threats?). This seems to be a novel theme in analysis of ko fights: using local threats is a kind of forcing play, holding them back can allow you time to simplify some issues.

Sorry if this seems complex ... ko just isn't that easy.



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