Speculative invasion

  Difficulty: Beginner   Keywords: EndGame

A favourite activity for beginners, social players, and weaker club players is to invade the opponent's territory quite near the end of the game, for no particular plan or reason.

This mostly wastes time, and the opponent's patience; and is certainly a bad habit. Of course there may well be a valid invasion. If not, you waste ko threats, and possibly points (by not reading properly, you can easily play gote moves).

This is really the small-scale version of the mochikomi mistake. Valid invasions can often be played rather earlier than the small endgame plays. Naturally that isn't always the case, in that shortage of liberties and cutting points are created by plays right up to the end of the game.

-- Charles Matthews

HolIgor: Despite many objections, I think that beginners must try everything to learn what could work and what could not. At the same time the opponents learn to defend. Eventually, some reading depth is developed as well as some notion of what are the weaknesses that needs to be protected.

This helps a lot later when you play yose in more serious games. One of the most difficult problems is whether to spend one more move defending or go for points elsewhere. Sometimes even O Meien does not read that properly. Weaker players tend to add stones for safety allowing opponents to keep sente. I think that it is better to practice a little bit while you are inexperienced. Later it would be a shame.

Tamsin: Good points, HolIgor, but may I ask why you cite O Meien in particular? (He's my favourite player and I won't hear a bad word said about him <grin>.)

Dave Sigaty: If I am not mistaken, HolIgor is making a subtle reference to Ladder Exercise 2 :-)

Tamsin: A-hah! But didn't he do well to come back from such a disaster and capture the 2000 Honinbo title :-)

Pajaro: Maybe HolIgor is thinking abouth the 50th Oza Title (2002), against Cho Chikun. In the first game, Cho won because O, with a won game, didn't want to lose a point in yose to defend a defect. Cho used this to win the game. But in the second game, Cho was kind enough to have another won game and let it go by time.

Gresil: What's the functional difference or relation between speculative invasion and Semedori? Why I'm asking it is that yesterday I lost a game by 0.5, and the last thing my opponent (20k) did was a really desperate-looking last-minute invasion attempt behind my 4th line wall - which may have set the result.

Charles Semedori is a high-level endgame technique, where giving up stones gains points (with best play on both sides). Speculative invasion is a downmarket attempt to see if your opponent will let you get away with something unreasonable. A speculative invasion can turn into semedori; but you are supposed to see this before you invade.


nachtrabe: Something I've seen twice recently on KGS that certainly is very impolite at any level of play is when a player passes to enter the scoring phase (after a pass), sees that they are behind, and uses undo so that they can perform a deep speculative invasion. This is extremely annoying, far more so than the speculative invasion itself would have been if done before the scoring phase.


Bill: I have to agree with Holigor. Even when I was at the mid-kyu level, I would often make a invasion as a ko threat, only to find that it succeeded in its own right. If I had made more speculative invasions as a beginner, I would have been better at seeing those opportunities.

As for invading when you are behind, you may think of that as looking for a place to resign?. Once, when I was 2-kyu, as Black in a two stone game I found myself far behind near the end of the game, made a speculative invasion which lived, and squeaked out a victory. Then I found out that my opponent was a 4-dan who thought I had said I was 2-dan! ;-)

Calvin: So, how strong to you have to get before this habit becomes significantly less frequent? If it tapers off, it might be a motivation for me to get stronger.

Bill: Speaking personally, Calvin, from what I have seen of your contributions here on SL, you have a good eye for the vital points of a position, even if you still need work on reading. Your reading skill will improve over time with study, practice, and experience. In your case I would think that making speculative invasions is a good habit. :-)


uxs: I don't think this is a bad habit. If you never try anything, how can you know what works and what doesn't ?

nachtrabe: There seems to be a distinct difference between the types of speculative invasions being discussed here. There is the "I need to live here/break this up if I want to have a chance" move and then there is the "it is the late endgame, I can't read out any way to live unless my opponent screws up, but I am going to invade anyway and hope for a mistake." (The alternative is "I am too lazy to read it out," which is no better).

The former can be experimentation, it can even involve a brilliant move and is seen in games with certain pros. It can also fall under the category of "I move here, he moves there, and then things get really complicated"--if you are behind that can be a good thing. The latter--depending on an error to win late in the endgame--is another matter.

See also: Stubborn Play


QWerner: I think this is actually a middlegame problem. If someone has to invade late in the game to win and start some timewasting, ugly and boring invasions, than he didn't realise in the middlegame that he will lose the game (or he didn't count the territory). So he should have given up the game earlier. Basicly he missed the timing for invasion and reduction ect. in the middlegame.


This is a copy of the living page "Speculative invasion" at Sensei's Library.
(OC) 2007 the Authors, published under the OpenContent License V1.0.
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