BQM 336
This is a capture problem composed by John Tromp, linked from his logic rules page
I tried several variations, but all of them seem to fail. Am I overlooking something obvious, or is the problem composed wrongly?
Attempt 1 - direct
The second attempt - capturing the ko - fails as well, as the ladder cannot be avoided.
Comment from author
I overlooked this ladder; I should've put the stones on a larger board...
-John
Attempt 3 - another failure
As seems forced there is nothing to stop White from making eyes.
Attempt 4 - capturing race
blubb: Funnily, I came to the attempts above in exactly the same order (while temporarily ignoring yours). The problem somehow looks to me as if the ko capture should be the solution but the creator missed the alternative ladder (which works regardless of the ataried white stone). On the other hand, John is a careful thinker, so all in all ... no clue.