One-Two-Three
There are a few ideas about three-move sequences that come up quite frequently.
Discussion here moved to /Discussion.
123 principle (concise)
Don't play ,
,
: just play
.
For example, in ''atari''-connect combinations, the atari should often be omitted and only the move that would connect should be played.
123 principle (verbose)
If, given the benefit of hindsight, you as Black can see that the /
exchange was something of a loss, then you should also consider that a player with better foresight would have tried to skip over it.
An example that comes up early in everyone's go career:
![[Diagram]](../../diagrams/28/34e997f854f73f7fd436c0885c59ac6f.png)
Hane-descend is poor
Here, after is answered by
, it is usually wrong to continue with
. That allows
forcing Black to defend.
Just playing is correct (in almost all cases). Now Black has the good follow-up endgame play at the circled point. And there remains some aji of the clamp at the square-marked point, too.
For more examples, see
A more involved case of the same idea is:
ABC principle
If Black has the choice of Black a, White b, Black c or Black b, White a, Black c, perhaps Black should simply play c.
This staircase shape is a reasonable example of the ABC principle. will often be correct, rather than Black's atari play at either of a or b.
This is one aspect of:
Don't play out miai
In the absence of a good reason, true miai points should probably not be played out, as an unmotivated exchange a-b.
Some more related ideas:
Forced answer advice
If you play a which you expect the opponent to answer at b, treating a as a forcing move, you should already know your follow-up play c. (From Tokimoto Hajime 8 dan.)
James Kerwin on urgent plays:
Treat a play at c as urgent if the opponent's play at b otherwise puts your earlier play at a at risk of being made meaningless. (Noted on play urgent moves before big moves.)
Bad tenuki
Playing /
and then playing tenuki as Black with
may be bad, if
can make playing
meaningless (see previous comment), or worse.
This might lead one to the
Theory of reversible plays
From CGT there is the quite profound idea of a reversible play. It again relates to thinking about a three-move 'block': Black a gives White an answer b which (probably) gives a position at least as good as the initial one, so Black ought to have the next play c lined up.
In this example the point is that Black has gained nothing yet, if we're just talking endgame. Simply playing and
isn't typically kikashi - effective forcing play - because White a is now better than it was before
was played.
See detailed discussion now at reversible play - loss and gain.