BQM128

Problem 10 of Maeda's Life and Death Intermediate Level Problems is the following:

White to save the marked stones  

The solution in the book is given in the next three diagrams:

Solution part 1  

Solution part 2  

Solution part 3  

Black is alive in the corner. White must win the ko to survive.

Isn't ko considered a failure in life and death problems?

SnotNose: Ko is not a failure unless the problem description says "White to live" or "white to live unconditionally." If the problem is "White to do the best she can" (like a one-sided "status" problem) then ko may be the solution. The hard part of problems of this type is you don't know when you've solved them. You find a ko and still wonder if you could have done better. (Actually, the situation I hate is when I find a ko and a seki. I can't decide which is best without knowing the whole board situation, which isn't given.)

dnerra: Minor nitpick: A "status problem" is, in my understanding, a problem where you are asked to decide

• what is the best White can do if she moves first, and
• what is the best Black can do if he moves first.

I.e., exactly what you have to do all the time in your own games.

Charles I agree with that. But Maeda almost always says just White to play, that is, gives a semi-status problem. The question here comes down therefore to what exactly the book says about the stones.

Velobici: The book says exactly the text used as the description of the first diagram, that is, White to save the marked stones. I understood that as the marked stones are to live unconditionally. The solution is Maeda is given in two diagrams. The exact text of the solution is:

Problem 10 Success: White must attack Black's corner group. With 1 and 3 White aims at creating a shortage of liberties problem for Black. This continues with White 5 and 7, which force Black to capture at 8 instead of connecting at 9. After White 9, Black must make life at 10. White captures four stones with 11, but must still deal with the ko caused by Black 12.