Korean Problem Academy / Errata

Problem 135  

Is the square 4 solution potentially better because of fewer ko threats?

Steve Kroon: I think that depends on the outside situation. Also, with white stones on the outside, making a square 4 might not kill the group, while playing on the outside can.

Problem 135  

unkx80: Thanks nachtrabe... anyway, if the solution is to be unique, then this should be the diagram. In the original diagram, I do not prefer the square four solution because it leaves more liberties, and hence aji, for White.

Level 2, Problem 11 - not an error

Level 2, Problem 11  

Query by Steve Kroon: The given solution connects at a creating a seki. But Black needn't play there yet: he can rather first connect the one stone on the right side to his larger group by playing at b (if he plays tenuki, a throw-in at the same point seems to lead to a ko for the life of the Black group. This move for Black also seems to lead to a seki, but Black's group ends with more aji to the outside, as well as more liberties.

Comments?

Ed?: If black starts at 'b' white could still close of the right side in sente by playing 'c' so it gains no points.

Level 2, Problem 11  

Ed?: may take an extra point, but black should be careful since if black can't capture after connecting (by playing 'a') he would be killed by at .

If white plays first, descending to would kill.

Level 2, Problem 60

Level 2, Problem 60  

OneTrueCalculus: Gobase gives 'a' as the only valid solution, but I can't see how it's different from 'b'.

jedwardh: I came here because of the same problem. My reading says that they both lead to seki. If anyone can demonstrate that 'a' is better than 'b', I'd be very interested to see how.

Level 2, Problem 178

I have a question concerning problem 178 on the 15k-5k level from the Korean Problem Academy problems, available on GoBase.

The position is shown here:

How to continue this solution?  

The solution given at gobase is . But I cannot find the proper answer to . After , white plays and lives.

xela: I spent a long time looking at this, and came to the same conclusion: there is no way to kill white, with or any other move. I think the problem diagram on gobase must be wrong.

Black to Kill  

Ectospheno: Apparently whoever put the problems on gobase took some liberties and changed the positions in the book. Problem 178 is obviously inspired from the 178th problem in book two but isn't the actual problem. Most of the level two problems on gobase deviate from what is in the book. The book has this position (rotated to match gobase orientation):

Level 3, Problem 97

Level 3, Problem 97  

OneTrueCalculus: The solution given is a, but b also lives (with fewer points).

Level 3, Problem 108

Another solution  

This is better than the given solution. Black gives up one stone, but leaves behind a two point gote to capture two White stones. Instead of 3 points of territory the count is 4 points (plus or minus 2 for the gote). Black is also better in terms of ko threats.

(LukeNine45: Bill, hope you don't mind my re-wording... :) )

LukeNine45: Unfortuniately, I got the diagram wrong. The stone above changes things:

One point worse  

Bill: With the stone, your solution is one point worse than the given solution. The point you gain giving one stone for a potential two stones is given back with - . In addition, with the usual assumption that the surrounding area is White territory, you have lost the one point sente at . Still, it deserves honorable mention. :-)

Level 4, Problem 29

Needless continuation  

buggler: The solution on gobase includes the continuation of moves 4 and 5 but white is already dead after move 3 and black can ignore 4.