Strange things happen at the one-two point
The 1-2 points have a number of peculiarities; and the heuristic principles of fighting, which normally apply to the sides, often work differently in the corner. These peculiarities lead to the saying "Strange things happen at the one-two point".
Some of the peculiarities of the 1-2 point include:
Impossibility to approach a stone at the 1-2 point from the corner 1-1 point. This can give the player who occupies the 1-2 point an additional tempo to win a capturing race. The double shortage of liberties situation illustrates this case.
Occupying both 1-2 points is the most efficient way of making an eye, provided that the 2-2 point cannot be occupied by the opponent. This aspect is a recurring theme in many corner life-and-death problems.
The 1-2 point can often be used to force a ko in the corner at the 1-1 point, such as the bent four in the corner as shown in this diagram. This has ramifications in both capturing races and life-and-death situations. A couple of endgame tesujis also rely on this peculiarity.
Here Black cannot attack from either side because of shortage of liberties.
In all problems Black has sente.
I will show another example.
Black played as a ko-threat. I will not discuss whether this was the best threat. White answered at giving Black another threat at a. White should have played at a.
Here was in answer to . In fact it also attacks ; and is a direct threat.
The throw-in , at the 1-2 point, captures , because of the weakness at a.
Thank you for correcting mistakes.
Black plays hoping for White's mistake. White sees the ko. White suspect that she wins the capturing race without ko (but it is so difficult to read 8 moves ahead, shame on her!), and she decides to fight the ko.
But the sad story of White's mistake has little to do with the topic, and the topic of this page is the 1-2 point. By taking it, Black got a ko that saved his group.
How is this a capturing race? After black's play at the 1-2, wouldn't white make life by:
The 1-2 point is a critical point in many life and death problems. The difference between living or dying locally is at least 20 points. It is something that cannot be taken easily. That's the difference between winning and losing, or losing and losing badly.
- Xuanxuan Qijing Unnumbered Problem 2
- RTG Problem 84
- Gokyo Shumyo, Section 1, Problem 2
- Endgame Problem 7