There are No Ko Threats in the Opening

    Keywords: Ko, Proverb

"There are no ko threats in the opening", because there is so much flexibility and fluidity in the opening (fuseki). As a practical matter, this is closely related to the difficulty of accurately assessing the gain or loss of plays in the opening. Just about any move that could be played as a ko threat can be ignored.


Charles Matthews A proverb, but not literally true. If a ko fight occurs in the early stages of the game, then apart from local ko threats there may be only threats to play two damaging stones against opening positions.

For example

[Diagram]

Enclosure



may become:

[Diagram]

Enclosure broken through



It is almost impossible to count this type of threat accurately, though by feel it is around 30 points (?).


Alex Weldon: My interpretation of the proverb is that although there are often moves in the opening that can be regarded as ko threats, they are rarely worth as much as the sorts of kos that break out in the opening. The reason for this is twofold:

1) Kos in the opening often involve one player's position collapsing entirely, and the opponent making one or more ponnukis, worth, according to the another proverb, 30 points apiece. For example:

[Diagram]

Typical fuseki situation permitting ko

This kind of position usually arises with other stones around, in a variety of ways, but I'm boiling it down to its essentials. W usually ataris at 1 before connecting at a, in order to forestall B at b (and gain a little profit in sente and possibly hurt B's eye potential, if there's a chance for an attack). Now, of course, B can cut at b, and W will have to fight a ko. However, compare the position when W wins to the position when B wins (I'm putting them both in one diagram to save space):

[Diagram]

Possible ko results

If W's position after winning the ko doesn't look that spectacular, consider that B has to take gote to follow through whatever threat he made (or else starting the ko was a total loss, without any compensation), so W will get to cut at a or engulf the corner on a large scale. From these results, it should be clear that the ko represents a swing of at least 15-20 points of raw territory in the corner for the winner (so 30-40 total swing) plus a ponnuki or two worth of influence. That influence is worth much more early in the game than in the final stages, after the fighting has cooled down and most of the board is settled.

2) Meanwhile, the sorts of ko threats that exist in the opening tend to be worth less than the ko threats that exist later in the game. The reason for that is that stones, in the fuseki, tend to be more spread out. A ko threat like the one given as an example on this page, although it renders the victim's stones almost useless when followed through, still only affects two stones. Endgame ko threats often threaten to cut off huge chains of stones, kill entire groups, etc.

Put these two together, and you find the reason (again, in my interpretation) for the proverb: as a general rule (exceptions exist, of course), the value (and number, though that's a different issue) of ko threats gets larger as the game goes on, while the value of the sorts of kos that get fought goes down. Therefore, there exists a certain point before which it is unlikely that one will find a ko threat larger than the ko (assuming the ko is one worth fighting at that stage in the first place). Hence "no ko threats in the opening." If I was to suggest a clearer phrasing for the proverb, I would say "There are no big enough ko threats in the opening," but I think it's fine as it is.


The above proverb is, as Charles says, not meant to be taken literally. Of course, there are ko threats in the opening. Why and where? See /Discussion.



This is a copy of the living page "There are No Ko Threats in the Opening" at Sensei's Library.
(OC) 2004 the Authors, published under the OpenContent License V1.0.
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