Puzzle / Missed opportunity to win

I was playing black. I missed an opportunity to win:
So I am 10Kyu rating. 30 second time increment game.

What I want to know is 2 things:

What is the thought process to start to being able to solve the problem?
What kind of level would see the solution (given the time frame)?

Just some notes / hints:
I already tried to capture the centre bottom white group and failed, or so I thought because it’s still dead apparently.


I’d say that I was looking for [1] cuts and [2] shortage of liberties. There’s one fairly obvious case (for my level, 3 dan) of [1].

My guess

Start a ko by throwing in at D6 ?

After White takes the ko at D7 Black has an excellent ko threat at F7.


I just don’t know why I can’t see it. Even now when I know the answer it still seems difficult to see.
This is a real blind spot for me.


One thing that might help, is associating this shape with a potential ko (like two tigers mouths facing each other). There’s other shapes on the sides and corners too.


Don’t worry, it’s hard. I’m a 4k and while I was sort of comfortable fighting kos when they happened for a longer time already, I only very recently started to look for kos actively and start them myself. After spending so much time learning the pattern of ‘I can’t play there because it’s self-atari’, its seemingly very hard to get the brain to accept that it can still be a good move.


Im ~2k and i also didnt see it at first glance… xd


I think the “kill sequence” works here because the combination of two things -

  1. black has a local ko threat at f7 which white “has to”* answer, and
  2. that white group is big enough to decide the game regardless what compensation white gets
    (after d6 d7 f7 f6 d6 it doesnt matter where white gets 2 moves in a row, black still wins if he ignores everything and just connects at d7)
  • actually its really bad idea for white to answer that local threat because white doesnt have any threats, in facts it would be better for marginally better for white to ignore f7 and simply connect the ko on d7. Black can then cut f6 which kills the j5 group and wins black the game. Whites can then play a6 and live in the corner, this is marginally better in points than answering f7 with f6 since it does save the one stone on e6 (doesnt matter as white still loses)

I wouldn’t expect a 10k presented with this board position for the first time to solve it in 30 seconds. But if its a 10k who has been playing the game that’s different, because given the shape the moves may have been played with intention towards the solution.

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