[...] White can slip into the corner with 1. Now the corner turns into White's territory. [...] White 1 here [is] big endgame.
(Learn to Play Go; Volume II)


Would you be so kind as to tell me whether 1 in the following picture would be as big endgame as 1 in the previous example?


Thanks.

No, it's about 3 points smaller, though black will answer once and then tenuki:

Click Here To Show Diagram Code

[go]$$W
$$ +----------------------
$$ | . . 7 5 6 . . . . . .
$$ | . 9 3 4 0 . . . . . .
$$ | . 1 8 X . . . . . X .
$$ | . . . , X . X . X , .
$$ | . . O . . . . . . . .
$$ | . . . O X X . . . . .
$$ | . . . . O O X X . . .
$$ | . . . O . . O . . . .
$$ | . . . . . O . . . . .
$$ | . . O , . . . . . , .
$$ | . . . . . . . . . . .[/go]

Click Here To Show Diagram Code

[go]$$W
$$ +----------------------
$$ | . 7 8 . . . . . . . .
$$ | . 5 2 6 . . . . . . .
$$ | . 3 1 X . . . . . X .
$$ | . . 9 0 X . X . X , .
$$ | . . O . . . . . . . .
$$ | . . . O X X . . . . .
$$ | . . . . O O X X . . .
$$ | . . . O . . O . . . .
$$ | . . . . . O . . . . .
$$ | . . O , . . . . . , .
$$ | . . . . . . . . . . .[/go]

(7-8 here is a bit better for white hence "about"). The key point is white's sente follow up of the kosumi at 3 in the first diagram reduces black's upper side territory a lot. If you attach you can't do this.

Please forgive my ignorance: where was B2 played in the first diagram from Uberdude?

There is an easy way to compare the plays.

Click Here To Show Diagram Code

[go]$$W Attachment
$$ +----------------------
$$ | . . . . . . . . . . .
$$ | . . 2 . . . . . . . .
$$ | . 3 1 X . . . . . X .
$$ | . . . , X . X . X , .
$$ | . . O . . . . . . . .
$$ | . . . O X X . . . . .
$$ | . . . . O O X X . . .
$$ | . . . O . . O . . . .
$$ | . . . . . O . . . . .
$$ | . . O , . . . . . , .
$$ | . . . . . . . . . . .[/go]

This is the normal result of the attachment.

Click Here To Show Diagram Code

[go]$$W Slide???
$$ +----------------------
$$ | . . . . . . . . . . .
$$ | . . 2 . . . . . . . .
$$ | . 1 3 X . . . . . X .
$$ | . . . , X . X . X , .
$$ | . . O . . . . . . . .
$$ | . . . O X X . . . . .
$$ | . . . . O O X X . . .
$$ | . . . O . . O . . . .
$$ | . . . . . O . . . . .
$$ | . . O , . . . . . , .
$$ | . . . . . . . . . . .[/go]

But if Black replied with to White would not continue with . OC, as Uberdude points out, Black does not have to reply to the slide. But the exchange, - , is clearly bad for White; so the original attachment is not as good as the slide.

_________________
The Adkins Principle:
At some point, doesn't thinking have to go on?
— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

Tenuki, as was in diagram 2. Both are gote yose plays. If black answers his move is smaller than white's initial move so white is happy to make points in sente.