jts wrote:
I don't think you can discuss this issue without asking whether by "sente" you are referring to the privilege or to the relative value of the play and the follow-up. If both players have a twenty-point gote follow-up, then it's neither black's sente nor white's sente, but double , right?
Or more accurately, both players have a gote move with a big gote follow-up (which itself might have more follow-up). For example:
$$c Double sente
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | X X X X . . . . . . . . . . . O O O O |
$$ | . X . X . . . . . . . . . . . O . O . |
$$ | X X X X X X X X X X O O O O O O O O O |
$$ | . . . , . . . . . X O . . . . , . . . |
$$ | . . . . . . . . . X O . . . . . . . . |
$$ | . . . . . . . . . X O 4 . . . . . . . |
$$ | . . . . . . . . . 3 1 2 . . . . . . . |
$$ ---------------------------------------
- Click Here To Show Diagram Code
[go]$$c Double sente
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | X X X X . . . . . . . . . . . O O O O |
$$ | . X . X . . . . . . . . . . . O . O . |
$$ | X X X X X X X X X X O O O O O O O O O |
$$ | . . . , . . . . . X O . . . . , . . . |
$$ | . . . . . . . . . X O . . . . . . . . |
$$ | . . . . . . . . . X O 4 . . . . . . . |
$$ | . . . . . . . . . 3 1 2 . . . . . . . |
$$ ---------------------------------------[/go]
This is a common double sente endgame position. But neither move is totally sente, white could omit

and lose a load of (hard to calculate exactly) points. Ditto for white going first into black's area to left. But the move is slightly more sente for white than black because black has a bigger territory (by 1 line) behind so stands to lose more should white end up playing 7 gotes or whatever it takes to turn it all to dame. In practice these considerations usually don't matter as it's easy to find the right stage of the game when that large hard-to-calculate-exactly potential loss of points is too big so the move is sente. But for an example of when a double sente move is more sente for one player than the other and would thus be a mistake, see my comment on move 108 of
http://www.lifein19x19.com/forum/viewto ... f=4&t=7635.
P.S. If Bill thinks calculating the value of the above position too easy and wants a challenge, how about:
$$c Argh!!!
$$ | . . . . . . . . . . . O O O . . . . . |
$$ | . . . . . . . . . . . O . O . . . . . |
$$ | X X X X . . . . . . . O . O . O O O O |
$$ | . X . X . . . . . . . O . O . O . O . |
$$ | X X X X X X X X X X O O . O O O O O O |
$$ | . . . , . . . . . X O . . . . , . . . |
$$ | . . . . . . . . . X O . . . . . . . . |
$$ | . . . . . . . . . X O 4 . . . . . . . |
$$ | . . . . . . . . . 3 1 2 . . . . . . . |
$$ ---------------------------------------
- Click Here To Show Diagram Code
[go]$$c Argh!!!
$$ | . . . . . . . . . . . O O O . . . . . |
$$ | . . . . . . . . . . . O . O . . . . . |
$$ | X X X X . . . . . . . O . O . O O O O |
$$ | . X . X . . . . . . . O . O . O . O . |
$$ | X X X X X X X X X X O O . O O O O O O |
$$ | . . . , . . . . . X O . . . . , . . . |
$$ | . . . . . . . . . X O . . . . . . . . |
$$ | . . . . . . . . . X O 4 . . . . . . . |
$$ | . . . . . . . . . 3 1 2 . . . . . . . |
$$ ---------------------------------------[/go]