More importantly than any shape problems, white's 2 groups are now cut and separated, with no way to capture the black cutting stones. Maybe Ed forgot to say this because it's obvious, but I think it's important to emphasise to PeterPeter in case he missed it. Any bad shape considerations are secondary the the fundamental failure here that white should have captured the cutting stones to connect his groups, but has failed to do so and is now separated into 2 groups.

I must have worn out poor EdLee , but for when he has recovered, I can think of 2 reasons:

1. It is nearer to, and therefore has more influence over, the shaded area.

2. Eyespace potential at A.

Click Here To Show Diagram Code

[go]$$W
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . O . . |
$$ | . X O . . . . . . . . . . . . . O X . |
$$ | . X O . . . . . . ? ? ? ? ? . . O X . |
$$ | . . X O . . . . . ? ? ? ? ? . O X . . |
$$ | . . X O 1 . . . . ? ? ? ? 1 a O X . . |
$$ | . . X X O . . . . ? ? ? ? ? O X X . . |
$$ | . . . . . . . . . ? ? ? ? ? . . . . . |
$$ -----------------------------------------[/go]

_________________
Regards,

Peter

3. Think about yose (endgame).

Click Here To Show Diagram Code

[go]$$W
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . O . . |
$$ | . X O . . . . . . . . . . . . . O X . |
$$ | . X O . . . . . . . . . . . . . O X . |
$$ | . . X O . . . . . , . . . . . O X . . |
$$ | . . X O 1 . . . . . . . . 1 b O X . . |
$$ | . . X X O . . . . . . . . a O X X . . |
$$ | . . . . . . . . . . . . . 3 2 4 . . . |
$$ -----------------------------------------[/go]

How about: after the standard endgame sequence , White does not need to worry about Black invading at A, but he would worry if were on B? And, therefore, White comes out with sente?

_________________
Regards,

Peter

Yes, the hanging connection makes that first line hane-connect gote for black, instead of sente with the solid, so it's better for the endgame (by 2 points).

Quite and extraordinary exchange!

@Peter Attaboy!
@Ed Well done teacher!

_________________
Dave Sigaty
"Short-lived are both the praiser and the praised, and rememberer and the remembered..."
- Marcus Aurelius; Meditations, VIII 21

EdLee has been an excellent and generous teacher on this and other threads, so instead of picking a single post of his to ‘like’, I will say it here: Thank you Ed.

_________________
Regards,

Peter

Peter, you're very welcome. You didn't wear me out at all, but it was already something like 4 in the morning,
and I had to get up early today.

Peter, nice job on comparing the tiger's mouth vs. the connect.
There are probably other good reasons, but I like these: better shape, better eye-space, better yose.You're correct, but it's a good question, and the basics behind it are important,
and it's good you now understand them better.