I know there’ll be a really obvious answer which will make me feel schtoopid, but I still would like to know the answer. Normally I can figure this stuff out eventually at my kyu pace, but this time not.
…I thought Black would play F2. Nope, they went off and did dan stuff elsewhere - I figured there was bigger value and that Black would come back to it. Nope, never did. I spent the rest of the game trying to figure out how to respond as White if Black played F2 - everything seems to end in either a killable eyeshape or ko. Wouldn’t this give ko for a bulky five?
In the last position of your sequence, White can squeeze and live (White atari → Black takes → White atari and Black cannot connect the bulky five).
And this seems to be the key sequence, I don’t see anything better. Your reading is fine, it’s the pattern matching at the end! I think it’s quite common when your tsumego sense is tuned on dead shapes that you have this kind of blind spots.
And avoiding white 2 being sente is one reason why in this joseki diagram solid connection at 1 is generally considered the proper move rather than the territorially superior descent at 2 as played in this game (there’s also effect on the cut to the left).
If I’m White then I’m dead (I can’t see seki or ko). Again, in my defense, I’m still waking up.
If I were in an optimistic mindset I’d consider each white move there as a ko threat to resurrect the group, but how many threats could be mined is for the pros to knows.
https://ps.waltheri.net/ a great site to pattern search pro games. It’s not as powerful as local programs such as kombilo + GoGoD (or other) database, but it’s very convenient being a free website.
I’m not spoiling the answer to the question of Animiral, but I just want to say that the sequence where Black exchanges E2 fo E3 before playing J1 was way trickier for me to read. The result is ultimately the same.
The overall lesson is that life is not just about nakade shapes. In this case, white has so much eye space that he can aim for seki. If this is your group in a real game, you will probably happily give up ~5 points if you get to keep your group and take sente in the middle game as well!
Stronger players view seki just the same as alive, to the point where even dan players may completely forget about the points value at times.
In a recent tournament game, my opponent had an enhanced carpenter’s square in the corner that could not be killed. The funny thing was that he looked a bit bewildered at my first move inside, like I was trying to kill it. We all encounter those who just try something inside, to provoke a blunder and sneak a kill in byo-yomi. Well, it turned to seki in sente (my sente). Can you imagine, the guy looked even less happy then!
I guess below high Dan or professional level, we could call it a blunder or just a blind spot.
If you give me a carpenter square even not in byo-yomi, I might mess it up just because I haven’t studied it and can’t read it out on the spot. It is a kind of blunder, but it might be that the person just doesn’t know the shape or sequence.
