Cho Chikun Life & Death 212


I am working on problem 212 of the problem set here. I wonder, why T16, leading to a ko, is not considered a correct answer, but Q19 leading to a double go? Could anyone give me a pointer?


(Edit: Add picture of the problem)

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Being alive in double ko is almost as good as unconditional life! Even if your opponent has many more ko threats than you, they can never kill you.

There is one drawback to double ko life - your opponent has infinitely many threats against that group, which they could use to win future ko fights.

But in practical terms, double ko life is generally a much better result than ko life.


Could we please please please get a way to share tsumego on OGS so that they appear in the same orientation and colours. Or else the coordinates people mention are useless.


There is.

Press the cog and turn off random colour and random orientation and it always looks the same for everyone after that (assuming everyone turns both those settings off)


I guess I should attach a screen capture showing the question. Updated my question just now.

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I see. If in this state:

In case white continue to tighten liberty of black by P19, black can take the ko at either S19 or T18. So black is effectively alive. White’s T17 is also a ko threat against black.

Yes I am aware of that setting. But people post links to problems where they haven’t turned them off, so even if I turn it off for me I will likely end up with a different orientation to the random one they had when they wrote their text with coordinates.

It is a fruitless battle trying to educate every OGS user sharing puzzle links that they need to turn off randomization. Instead they should be off by default, or the url should encode the chosen randomization setting as query parameters so that when shared they are reproduced for observers.


this sounds like a promising option… not sure if it would be possible without backend support or not though…


I think that everyone interested in solving puzzles would have them on by default.

I understand your frustration but I fear we’ll have to deal with it, maybe with a simple answer “pic, please”. :man_shrugging:

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Sincerely I like solving and i prefer to not have to check if i play black or white. The conventional black to play is perfect for me.


What tends to actually happen is confused people reply with things like “What do you mean a18, this problem is in the bottom right corner” or “Black’s already alive, white can’t kill” until someone like me comes along and explains about OGS problem randomization. See many examples over on r/baduk over the years.