Strange things happen at the one-two point

    Keywords: Tactics, Proverb

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".


Peculiarities

Some of the peculiarities of the 1-2 point include:

[Diagram]
Winning a capturing race  

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.

[Diagram]
Eye in corner  

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.

[Diagram]
Ko in corner  

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.


Example

[Diagram]
Usual way to fight a capturing race  

In this case Black wins.

[Diagram]
Take the 1-2 point first  

White wins.

Here Black cannot attack from either side because of shortage of liberties.


Exercises

tderz: From WeiQi the predecessor of WeiQi TianDi, 1980, Nr. 4, p.31 and, of course, some other famous sources..

In all problems Black has sente.

[Diagram]
Problem 1  

/Problem 1 Attempts
/Problem 1 Solution?

[Diagram]
Problem 2  

/Problem 2 Attempts
/Problem 2 Solution?

[Diagram]
Problem 3  

/Problem 3 Attempts
/Problem 3 Solution?

[Diagram]
Problem 4  

/Problem 4 Attempts?
/Problem 4 Solution?

[Diagram]
Problem 5  

/Problem 5 Attempts?
/Problem 5 Solution?

[Diagram]
Problem 6  

/Problem 6 Attempts
/Problem 6 Solution?


Another feature of the 1-2 point is the possibity of a throw in tesuji. An example is considered at Stupid Moves.

I will show another example.

[Diagram]
White 2 was a small mistake  

Black played B1 as a ko-threat. I will not discuss whether this was the best threat. White answered at W2 giving Black another threat at a. White should have played at a.

[Diagram]
A direct atari  

Here white+circle was in answer to black+circle. In fact it also attacks black+circle; and is a direct threat.

The throw-in W1, at the 1-2 point, captures black+circle, because of the weakness at a.

Actually I can point to a stupid player with White who lost a ko because of this mistake. It was a certain HolIgor (IGS 5k*).

Thank you for correcting mistakes.


The 1-2 point is a place where many kos happen. For example, the ko that HolIgor (IGS 5k*) lost.

[Diagram]
Black starts ko  

Black plays B1 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:

[Diagram]
White makes life  

or

[Diagram]
Guess there's a disadvantageous ko here...  

-- Malweth


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.

Examples

See also:


Strange things happen at the one-two point last edited by Unkx80 on March 10, 2014 - 19:07
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