@Uberdude, I liked your m7 variation for white but do not completely share the concern of white's exposition to an (far fetched) attack on the right, wouldn't it be ineffective for black? Actually, following black's s14 in that variation I would even consider playing p3 to (possibly) induce him for another move at the right (s6 maybe) even then white's r12 group seems to be quite in safe and black doesn't get much territory.

Poor Ke Jie, made another stupid late endgame blunder (n11 timesuji* was gote) in a final vs Park so lost by 1.5. Park wins his 3rd World Go Championship in a row.
* Actually it does defend against black L11 so not as inexplicable as it appeared.
P.S. Why was f3 necessary at that time? I can see some shortage of liberties troubles if white connects in response to the m6 atari but that's just a 5ish point gote so couldn't white do a11 sente endgame first? On the stream Ke Jie was obviously getting flustered, not placing stones at the correct point (n11 was played at o11 right at end of overtime period and he moved it to n11, maybe letting go of it first, naughty!) whereas Park remained calm.

I was wondering the same - I found a possible answer in the Japanese commentary on WBaduk, sorry for just posting it as a screenshot.

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Sorin - 361points.com

I don't think it was "timesuji", as in thinking it's forcing - it is a big move. I think he just miscalculated the size of the other move Park played, maybe realizing too late that F4 is sente.

Here is the moment he played O11-turned-N11: https://youtu.be/QI6QEAdNbOM?t=21998

If you keep watching a couple more minutes, he slapped himself several times (with breaks in between).

Later, technically, he even takes a move back, but then replayed in the same place: https://youtu.be/QI6QEAdNbOM?t=22824

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Sorin - 361points.com

sorin, nice, I didn't see the 1st line atari of 8, just the peep on 2nd line. My idea was white could play a11 for sente profit before coming back to f3 if it is indeed necessary. Trouble is W f14 / B g14 is so big and tedomari. I played out the endgame with both white f3 and allowing black g14, and white taking f14 so sacrificing the m5 stones and white still lost, but only by half a point instead of 1.5. Heres an sgf with variations (don't pay too much attention to the LZ percentages in the file as they assume 7.5 komi). Go to variation on move 250.

P.S. If white captured at f4 instead of n11 then even if he allows L11 to connect instead of fighting the ko I get a half point win for white.

I had the same questions as you do - why doesn't white play hane on the left first (A11), at least, before connecting at F3 - but like you said, the local profit on the left is not "free" at all, it has implications towards the right.

I was also surprised that white didn't find time to play hane-connect on the first line though (N1) before black played (what looks like) reverse-sente M1. I guess that's because N1 is not really sente.

Such a complicated endgame even if the position looks relatively simple.
We need Bill's mathematical endgame approach here

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Sorin - 361points.com

Agreed. This was not nearly as bad an error as the other game. The move itself had significant value and removed any variation related to the potential ko. The key mistake was to not realize b247 was sente, which doubled its value, but that's much more understandable.

What if the World Go championship operated like a traditional big seven tournament in Japan such as the Meijin or Honinbo (seeding in the prelims based on last years perfomance, one-by-one games instead of one large preliminary)? Perhaps such a thing is unrealistic nowdays, but considering it's one of the few international Japanese tournaments, it seems a good opportunity to give some of it's 'spirit' (and maybe make it more familiar for professionals playing in Japan).

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On Go proverbs:
"A fine Gotation is a diamond in the hand of a dan of wit and a pebble in the hand of a kyu" —Joseph Raux misquoted.