It was an H3 game between Zang Nianxuan (W) and Fang Zuozhou in Qing Dynasty (circa 1700 AD).
Problem #1. Level: Easy (for SDKs?)
$$Wc Position at move 94 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . X . . . . . . . . . . . | $$ | . X X . X X . . O . O . X . . . . O . | $$ | . . O , . O O . . , . . . . X X . X X | $$ | . . . O . . . . . . O . X X O . X O . | $$ | . . . . . . . . . O X X . O O . O O . | $$ | . . . . . . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . . . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . . . X X O O X O O X . | $$ | . . X . . . . . . . . O . . X X X . . | $$ | . . . . . . . . . . . . . O . O X a . | $$ | . . O . O . . . . . . . . . . X O X . | $$ | . . . . . . . . . . . . . O O . O O . | $$ | . . . X . . . . . , . . O X O , O . . | $$ | . . . . . . X . O . . X . X X X O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------
[go]$$Wc Position at move 94 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . X . . . . . . . . . . . | $$ | . X X . X X . . O . O . X . . . . O . | $$ | . . O , . O O . . , . . . . X X . X X | $$ | . . . O . . . . . . O . X X O . X O . | $$ | . . . . . . . . . O X X . O O . O O . | $$ | . . . . . . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . . . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . . . X X O O X O O X . | $$ | . . X . . . . . . . . O . . X X X . . | $$ | . . . . . . . . . . . . . O . O X a . | $$ | . . O . O . . . . . . . . . . X O X . | $$ | . . . . . . . . . . . . . O O . O O . | $$ | . . . X . . . . . , . . O X O , O . . | $$ | . . . . . . X . O . . X . X X X O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]
White to play. What's the status of the black group on the right side? Specifically, if white plays 'a', can black live?
Re: 3 L&D problems from an ancient Chinese game
Posted: Sun Dec 26, 2010 11:05 am
by Gresil
A nice problem!
I can't find anything.
$$Wc Position at move 94 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . X . . . . . . . . . . . | $$ | . X X . X X . . O . O . X . . . . O . | $$ | . . O , . O O . . , . . . . X X . X X | $$ | . . . O . . . . . . O . X X O . X O . | $$ | . . . . . . . . . O X X . O O . O O . | $$ | . . . . . . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . . . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . . . X X O O X O O X . | $$ | . . X . . . . . . . 9 O 5 4 X X X 2 . | $$ | . . . . . . . . . . . 8 6 O . O X 1 . | $$ | . . O . O . . . . . . . . 7 . X O X 3 | $$ | . . . . . . . . . . . . . O O . O O . | $$ | . . . X . . . . . , . . O X O , O . . | $$ | . . . . . . X . O . . X . X X X O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------
[go]$$Wc Position at move 94 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . X . . . . . . . . . . . | $$ | . X X . X X . . O . O . X . . . . O . | $$ | . . O , . O O . . , . . . . X X . X X | $$ | . . . O . . . . . . O . X X O . X O . | $$ | . . . . . . . . . O X X . O O . O O . | $$ | . . . . . . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . . . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . . . X X O O X O O X . | $$ | . . X . . . . . . . 9 O 5 4 X X X 2 . | $$ | . . . . . . . . . . . 8 6 O . O X 1 . | $$ | . . O . O . . . . . . . . 7 . X O X 3 | $$ | . . . . . . . . . . . . . O O . O O . | $$ | . . . X . . . . . , . . O X O , O . . | $$ | . . . . . . X . O . . X . X X X O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]
Not this —the ladder doesn't work.
$$Wc Position at move 94 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . X . . . . . . . . . . . | $$ | . X X . X X . . O . O . X . . . . O . | $$ | . . O , . O O . . , . . . . X X . X X | $$ | . . . O . . . . . . O . X X O . X O . | $$ | . . . . . . . . . O X X . O O . O O . | $$ | . . . . . . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . . . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . . . X X O O X O O X . | $$ | . . X . . . . . . . . O 4 5 X X X 2 . | $$ | . . . . . . . . . . . . 9 O 7 O X 1 . | $$ | . . O . O . . . . . . . . 8 6 X O X 3 | $$ | . . . . . . . . . . . . . O O . O O . | $$ | . . . X . . . . . , . . O X O , O . . | $$ | . . . . . . X . O . . X . X X X O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------
[go]$$Wc Position at move 94 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . X . . . . . . . . . . . | $$ | . X X . X X . . O . O . X . . . . O . | $$ | . . O , . O O . . , . . . . X X . X X | $$ | . . . O . . . . . . O . X X O . X O . | $$ | . . . . . . . . . O X X . O O . O O . | $$ | . . . . . . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . . . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . . . X X O O X O O X . | $$ | . . X . . . . . . . . O 4 5 X X X 2 . | $$ | . . . . . . . . . . . . 9 O 7 O X 1 . | $$ | . . O . O . . . . . . . . 8 6 X O X 3 | $$ | . . . . . . . . . . . . . O O . O O . | $$ | . . . X . . . . . , . . O X O , O . . | $$ | . . . . . . X . O . . X . X X X O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]
Not this either.
$$Bc Position at move 94 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . X . . . . . . . . . . . | $$ | . X X . X X . . O . O . X . . . . O . | $$ | . . O , . O O . . , . . . . X X . X X | $$ | . . . O . . . . . . O . X X O . X O . | $$ | . . . . . . . . . O X X . O O . O O . | $$ | . . . . . . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . . . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . . . X X O O X O O X . | $$ | . . X . . . . . . . . O 4 3 X X X X . | $$ | . . . . . . . . . . . . 1 O . O X O . | $$ | . . O . O . . . . . . . . 2 . X O . O | $$ | . . . . . . . . . . . . . O O . O O . | $$ | . . . X . . . . . , . . O X O , O . . | $$ | . . . . . . X . O . . X . X X X O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------
[go]$$Bc Position at move 94 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . X . . . . . . . . . . . | $$ | . X X . X X . . O . O . X . . . . O . | $$ | . . O , . O O . . , . . . . X X . X X | $$ | . . . O . . . . . . O . X X O . X O . | $$ | . . . . . . . . . O X X . O O . O O . | $$ | . . . . . . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . . . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . . . X X O O X O O X . | $$ | . . X . . . . . . . . O 4 3 X X X X . | $$ | . . . . . . . . . . . . 1 O . O X O . | $$ | . . O . O . . . . . . . . 2 . X O . O | $$ | . . . . . . . . . . . . . O O . O O . | $$ | . . . X . . . . . , . . O X O , O . . | $$ | . . . . . . X . O . . X . X X X O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]
Transposes to the ladder.
$$Bc Position at move 94 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . X . . . . . . . . . . . | $$ | . X X . X X . . O . O . X . . . . O . | $$ | . . O , . O O . . , . . . . X X . X X | $$ | . . . O . . . . . . O . X X O . X O . | $$ | . . . . . . . . . O X X . O O . O O . | $$ | . . . . . . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . . . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . . . X X O O X O O X . | $$ | . . X . . . . . . . . O 4 3 X X X X . | $$ | . . . . . . . . . . . . 5 O 1 O X O . | $$ | . . O . O . . . . . . . . 6 2 X O . O | $$ | . . . . . . . . . . . . . O O . O O . | $$ | . . . X . . . . . , . . O X O , O . . | $$ | . . . . . . X . O . . X . X X X O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------
[go]$$Bc Position at move 94 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . X . . . . . . . . . . . | $$ | . X X . X X . . O . O . X . . . . O . | $$ | . . O , . O O . . , . . . . X X . X X | $$ | . . . O . . . . . . O . X X O . X O . | $$ | . . . . . . . . . O X X . O O . O O . | $$ | . . . . . . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . . . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . . . X X O O X O O X . | $$ | . . X . . . . . . . . O 4 3 X X X X . | $$ | . . . . . . . . . . . . 5 O 1 O X O . | $$ | . . O . O . . . . . . . . 6 2 X O . O | $$ | . . . . . . . . . . . . . O O . O O . | $$ | . . . X . . . . . , . . O X O , O . . | $$ | . . . . . . X . O . . X . X X X O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]
The same ladder again.
$$Bc Position at move 94 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . X . . . . . . . . . . . | $$ | . X X . X X . . O . O . X . . . . O . | $$ | . . O , . O O . . , . . . . X X . X X | $$ | . . . O . . . . . . O . X X O . X O . | $$ | . . . . . . . . . O X X . O O . O O . | $$ | . . . . . . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . . . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . . . X X O O X O O X . | $$ | . . X . . . . . . . . O . . X X X X . | $$ | . . . . . . . . . . . . 4 O . O X O . | $$ | . . O . O . . . . . . . 3 1 2 X O . O | $$ | . . . . . . . . . . . . . O O . O O . | $$ | . . . X . . . . . , . . O X O , O . . | $$ | . . . . . . X . O . . X . X X X O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------
[go]$$Bc Position at move 94 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . X . . . . . . . . . . . | $$ | . X X . X X . . O . O . X . . . . O . | $$ | . . O , . O O . . , . . . . X X . X X | $$ | . . . O . . . . . . O . X X O . X O . | $$ | . . . . . . . . . O X X . O O . O O . | $$ | . . . . . . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . . . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . . . X X O O X O O X . | $$ | . . X . . . . . . . . O . . X X X X . | $$ | . . . . . . . . . . . . 4 O . O X O . | $$ | . . O . O . . . . . . . 3 1 2 X O . O | $$ | . . . . . . . . . . . . . O O . O O . | $$ | . . . X . . . . . , . . O X O , O . . | $$ | . . . . . . X . O . . X . X X X O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]
Nah.
Re: 3 L&D problems from an ancient Chinese game
Posted: Sun Dec 26, 2010 11:16 am
by Numsgil
@Gresil
What about aiming for a loose ladder?
$$Wc Position at move 94 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . X . . . . . . . . . . . | $$ | . X X . X X . . O . O . X . . . . O . | $$ | . . O , . O O . . , . . . . X X . X X | $$ | . . . O . . . . . . O . X X O . X O . | $$ | . . . . . . . . . O X X . O O . O O . | $$ | . . . . . . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . . . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . . . X X O O X O O X . | $$ | . . X . . . . . . . 9 O 5 4 X X X 2 . | $$ | . . . . . . . . . 0 . 8 6 O . O X 1 . | $$ | . . O . O . . . . . . . . 7 . X O X 3 | $$ | . . . . . . . . . . . . . O O . O O . | $$ | . . . X . . . . . , . . O X O , O . . | $$ | . . . . . . X . O . . X . X X X O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------
[go]$$Wc Position at move 94 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . X . . . . . . . . . . . | $$ | . X X . X X . . O . O . X . . . . O . | $$ | . . O , . O O . . , . . . . X X . X X | $$ | . . . O . . . . . . O . X X O . X O . | $$ | . . . . . . . . . O X X . O O . O O . | $$ | . . . . . . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . . . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . . . X X O O X O O X . | $$ | . . X . . . . . . . 9 O 5 4 X X X 2 . | $$ | . . . . . . . . . 0 . 8 6 O . O X 1 . | $$ | . . O . O . . . . . . . . 7 . X O X 3 | $$ | . . . . . . . . . . . . . O O . O O . | $$ | . . . X . . . . . , . . O X O , O . . | $$ | . . . . . . X . O . . X . X X X O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]
Re: 3 L&D problems from an ancient Chinese game
Posted: Sun Dec 26, 2010 11:40 am
by Gresil
Whoops.
Re: 3 L&D problems from an ancient Chinese game
Posted: Sun Dec 26, 2010 2:09 pm
by hiyayang
Nice job, Numsgil and Gresil! Gresil was just one move away from the solution, but he saved me a lot of work posting the variations.
For beginners, here is a variation that most people first thought about and that didn't work (with a correction to one of Gresil's variations):
$$Bc Black fails, after white captures the black stone at S6 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . X . . . . . . . . . . . | $$ | . X X . X X . . O . O . X . . . . O . | $$ | . . O , . O O . . , . . . . X X . X X | $$ | . . . O . . . . . . O . X X O . X O . | $$ | . . . . . . . . . O X X . O O . O O . | $$ | . . . . . . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . . . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . . . X X O O X O O X . | $$ | . . X . . . . . . a 8 O 4 3 X X X X . | $$ | . . . . . . . . . b . 7 5 O 1 O X O . | $$ | . . O . O . . . . . . . 6 . 2 X O . O | $$ | . . . . . . . . . . . . . O O . O O . | $$ | . . . X . . . . . , . . O X O , O . . | $$ | . . . . . . X . O . . X . X X X O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------
[go]$$Bc Black fails, after white captures the black stone at S6 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . X . . . . . . . . . . . | $$ | . X X . X X . . O . O . X . . . . O . | $$ | . . O , . O O . . , . . . . X X . X X | $$ | . . . O . . . . . . O . X X O . X O . | $$ | . . . . . . . . . O X X . O O . O O . | $$ | . . . . . . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . . . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . . . X X O O X O O X . | $$ | . . X . . . . . . a 8 O 4 3 X X X X . | $$ | . . . . . . . . . b . 7 5 O 1 O X O . | $$ | . . O . O . . . . . . . 6 . 2 X O . O | $$ | . . . . . . . . . . . . . O O . O O . | $$ | . . . X . . . . . , . . O X O , O . . | $$ | . . . . . . X . O . . X . X X X O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]
At this point, neither 'a' nor 'b' works for black.
White can also play at , to the same effect. Actually, there is a bonus question derived from this:
$$Bc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . X . . . . . . . . . . . | $$ | . X X . X X . . O . O . X . . . . O . | $$ | . . O , . O O . . , . . . . X X . X X | $$ | . . . O . . . . . . O . X X O . X O . | $$ | . . . . . . . . . O X X . O O . O O . | $$ | . . . . . . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . . . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . . . X X O O X O O X . | $$ | . . X . . . . . . a . O 4 3 X X X X . | $$ | . . . . . . . . . . . 6 5 O 1 O X O . | $$ | . . O . O . . . . . . 9 7 8 2 X O . O | $$ | . . . . . . . . . . . . . O O . O O . | $$ | . . . X . . . . . , . . O X O , O . . | $$ | . . . . . . X . O . . X . X X X O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------
[go]$$Bc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . X . . . . . . . . . . . | $$ | . X X . X X . . O . O . X . . . . O . | $$ | . . O , . O O . . , . . . . X X . X X | $$ | . . . O . . . . . . O . X X O . X O . | $$ | . . . . . . . . . O X X . O O . O O . | $$ | . . . . . . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . . . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . . . X X O O X O O X . | $$ | . . X . . . . . . a . O 4 3 X X X X . | $$ | . . . . . . . . . . . 6 5 O 1 O X O . | $$ | . . O . O . . . . . . 9 7 8 2 X O . O | $$ | . . . . . . . . . . . . . O O . O O . | $$ | . . . X . . . . . , . . O X O , O . . | $$ | . . . . . . X . O . . X . X X X O . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]
How does white escape? Does 'a' work?
Re: 3 L&D problems from an ancient Chinese game
Posted: Sun Dec 26, 2010 2:40 pm
by hiyayang
Spoiler alert: Stop here if you want to work on the first problem, as the diagram below contains the spoiler.
Problem #2. Level: Medium
$$Bc Position at move 157 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . X X . X X . X O . O . X . . . . O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . O . X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X . . | $$ | . . . . . . O O X X X O X O . O X . . | $$ | . O O . O O X . O . . . . . . X O X . | $$ | . O X . . X X . O X X O . O O . O O . | $$ | O X X X . . . X O O X X O X O , O . . | $$ | . O O X . X X . O . O X . X X X O . . | $$ | . . . . X O O . . . O X . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------
[go]$$Bc Position at move 157 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . X X . X X . X O . O . X . . . . O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . O . X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X . . | $$ | . . . . . . O O X X X O X O . O X . . | $$ | . O O . O O X . O . . . . . . X O X . | $$ | . O X . . X X . O X X O . O O . O O . | $$ | O X X X . . . X O O X X O X O , O . . | $$ | . O O X . X X . O . O X . X X X O . . | $$ | . . . . X O O . . . O X . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]
Black to play. How does the black group extending from lower-right corner to center live? Hint: Running out is not an option.
Re: 3 L&D problems from an ancient Chinese game
Posted: Sun Dec 26, 2010 2:55 pm
by Gresil
This seems to work:
$$Bc Position at move 157 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . X X . X X . X O . O . X . . . . O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . O . X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X . . | $$ | . . . . . . O O X X X O X O . O X . . | $$ | . O O . O O X . O . . 5 6 . . X O X . | $$ | . O X . . X X . O X X O 7 O O . O O . | $$ | O X X X . . . X O O X X O X O , O . . | $$ | . O O X . X X . O . O X 1 X X X O . . | $$ | . . . . X O O . . . O X . . 3 2 4 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------
[go]$$Bc Position at move 157 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . X X . X X . X O . O . X . . . . O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . O . X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X . . | $$ | . . . . . . O O X X X O X O . O X . . | $$ | . O O . O O X . O . . 5 6 . . X O X . | $$ | . O X . . X X . O X X O 7 O O . O O . | $$ | O X X X . . . X O O X X O X O , O . . | $$ | . O O X . X X . O . O X 1 X X X O . . | $$ | . . . . X O O . . . O X . . 3 2 4 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]
Without it black only gets a ko from the atari of M6:
$$Bc Position at move 157 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . X X . X X . X O . O . X . . . . O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . O . X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X . . | $$ | . . . . . . O O X X X O X O . O X . . | $$ | . O O . O O X . O . . 1 2 . . X O X . | $$ | . O X . . X X . O X X O 3 O O . O O . | $$ | O X X X . . . X O O X X O X O , O . . | $$ | . O O X . X X . O . O X . X X X O . . | $$ | . . . . X O O . . . O X . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------
[go]$$Bc Position at move 157 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . X X . X X . X O . O . X . . . . O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . O . X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X . . | $$ | . . . . . . O O X X X O X O . O X . . | $$ | . O O . O O X . O . . 1 2 . . X O X . | $$ | . O X . . X X . O X X O 3 O O . O O . | $$ | O X X X . . . X O O X X O X O , O . . | $$ | . O O X . X X . O . O X . X X X O . . | $$ | . . . . X O O . . . O X . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]
But can't black live by just extending his eyespace? Does white have a more severe attack than than this ?
$$Bc Position at move 157 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . X X . X X . X O . O . X . . . . O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . O . X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X . . | $$ | . . . . . . O O X X X O X O . O X . . | $$ | . O O . O O X . O . . . . . . X O X . | $$ | . O X . . X X . O X X O . O O . O O . | $$ | O X X X . . . X O O X X O X O , O . . | $$ | . O O X . X X . O . O X 3 X X X O . . | $$ | . . . . X O O . . . O X 2 5 . . 1 9 . | $$ | . . . . . . . . . . 8 4 6 7 . . . . . | $$ ---------------------------------------
[go]$$Bc Position at move 157 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . X X . X X . X O . O . X . . . . O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . O . X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X . . | $$ | . . . . . . O O X X X O X O . O X . . | $$ | . O O . O O X . O . . . . . . X O X . | $$ | . O X . . X X . O X X O . O O . O O . | $$ | O X X X . . . X O O X X O X O , O . . | $$ | . O O X . X X . O . O X 3 X X X O . . | $$ | . . . . X O O . . . O X 2 5 . . 1 9 . | $$ | . . . . . . . . . . 8 4 6 7 . . . . . | $$ ---------------------------------------[/go]
Re: 3 L&D problems from an ancient Chinese game
Posted: Mon Dec 27, 2010 6:05 am
by hiyayang
Hint (and @ Gresil):
Note that White has a series of sente moves to threaten the black group on the right. For example,
$$Wc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . X X . X X . X O . O . X . . . . O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . O . X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X 2 . | $$ | . . . . . . O O X X X O X O 6 O X 1 . | $$ | . O O . O O X . O . . . 5 . 4 X O X 3 | $$ | . O X . . X X . O X X O . O O . O O . | $$ | O X X X . . . X O O X X O X O , O . . | $$ | . O O X . X X . O . O X . X X X O . . | $$ | . . . . X O O . . . O X . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------
[go]$$Wc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . X X . X X . X O . O . X . . . . O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . O . X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X 2 . | $$ | . . . . . . O O X X X O X O 6 O X 1 . | $$ | . O O . O O X . O . . . 5 . 4 X O X 3 | $$ | . O X . . X X . O X X O . O O . O O . | $$ | O X X X . . . X O O X X O X O , O . . | $$ | . O O X . X X . O . O X . X X X O . . | $$ | . . . . X O O . . . O X . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]
Therefore, you have to be careful not to play moves that could get either black group killed.
Re: 3 L&D problems from an ancient Chinese game
Posted: Mon Dec 27, 2010 6:09 am
by hiyayang
@Gresil:
$$Bc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . X X . X X . X O . O . X . . . . O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . O . X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X . . | $$ | . . . . . . O O X X X O X O . O X . . | $$ | . O O . O O X . O . . . . . . X O X . | $$ | . O X . . X X . O X X O . O O . O O . | $$ | O X X X . . . X O O X X O X O , O . . | $$ | . O O X . X X . O . O X . X X X O . . | $$ | . . . . X O O . . . O X . . . . 1 2 . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------
[go]$$Bc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . X X . X X . X O . O . X . . . . O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . O . X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X . . | $$ | . . . . . . O O X X X O X O . O X . . | $$ | . O O . O O X . O . . . . . . X O X . | $$ | . O X . . X X . O X X O . O O . O O . | $$ | O X X X . . . X O O X X O X O , O . . | $$ | . O O X . X X . O . O X . X X X O . . | $$ | . . . . X O O . . . O X . . . . 1 2 . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]
How would black respond to ?
Re: 3 L&D problems from an ancient Chinese game
Posted: Fri Dec 31, 2010 7:43 pm
by hiyayang
Solution to Problem #2: In the actual game the following moves were played, which are believed to be optimal --
$$Bc Moves 158 to 167, black to live with ko $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . X X . X X . X O . O . X . . . . O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . O . X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X . . | $$ | . . . . . . O O X X X O X O . O X . . | $$ | . O O . O O X 0 O . . . . . . X O X . | $$ | . O X . . X X . O X X O . O O . O O . | $$ | O X X X . . . X O O X X O X O , O . . | $$ | . O O X . X X . O . O X . X X X O . . | $$ | . . . . X O O 7 8 . O X . . . 4 1 2 . | $$ | . . . . . 9 . . . . . . . . . 5 6 3 . | $$ ---------------------------------------
[go]$$Bc Moves 158 to 167, black to live with ko $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . X X . X X . X O . O . X . . . . O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . O . X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X . . | $$ | . . . . . . O O X X X O X O . O X . . | $$ | . O O . O O X 0 O . . . . . . X O X . | $$ | . O X . . X X . O X X O . O O . O O . | $$ | O X X X . . . X O O X X O X O , O . . | $$ | . O O X . X X . O . O X . X X X O . . | $$ | . . . . X O O 7 8 . O X . . . 4 1 2 . | $$ | . . . . . 9 . . . . . . . . . 5 6 3 . | $$ ---------------------------------------[/go]
$$B Moves 168 to 177, 9 at 1 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . X X . X X . X O . O . X . . . . O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . . . 7 . X O X O . O X . | $$ | . . . , . . . 8 6 X X X X X O O X X . | $$ | . . . . . . . 5 O . X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X 3 . | $$ | . . . . . . O O X X X O X O . O X 2 . | $$ | . O O . O O X O O . . . . . . X O X 0 | $$ | . O X . . X X . O X X O . O O . O O . | $$ | O X X X . . . X O O X X O X O , O . . | $$ | . O O X . X X . O . O X . X X X O . . | $$ | . . . . X O O X O . O X . . . O 1 O . | $$ | . . . . . X . . . . . . . . . X 4 X . | $$ ---------------------------------------
[go]$$B Moves 168 to 177, 9 at 1 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . X X . X X . X O . O . X . . . . O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . . . 7 . X O X O . O X . | $$ | . . . , . . . 8 6 X X X X X O O X X . | $$ | . . . . . . . 5 O . X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X 3 . | $$ | . . . . . . O O X X X O X O . O X 2 . | $$ | . O O . O O X O O . . . . . . X O X 0 | $$ | . O X . . X X . O X X O . O O . O O . | $$ | O X X X . . . X O O X X O X O , O . . | $$ | . O O X . X X . O . O X . X X X O . . | $$ | . . . . X O O X O . O X . . . O 1 O . | $$ | . . . . . X . . . . . . . . . X 4 X . | $$ ---------------------------------------[/go]
$$B Moves 178 to 187, 8 at 2 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . X X . X X . X O . O . X . . . . O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . 0 . X . X O X O . O X . | $$ | . . . , 4 . 9 O O X X X X X O O X X . | $$ | . . . . . . 3 X O . X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X X . | $$ | . . . . . . O O X X X O X O 7 O X O . | $$ | . O O . O O X O O . . . 6 . 1 X O . O | $$ | . O X . . X X . O X X O . O O . O O . | $$ | O X X X . . . X O O X X O X O , O . . | $$ | . O O X . X X . O . O X . X X X O . . | $$ | . . . . X O O X O . O X . . . O 5 O . | $$ | . . . . . X . . . . . . . . . X 2 X . | $$ ---------------------------------------
[go]$$B Moves 178 to 187, 8 at 2 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . X X . X X . X O . O . X . . . . O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . 0 . X . X O X O . O X . | $$ | . . . , 4 . 9 O O X X X X X O O X X . | $$ | . . . . . . 3 X O . X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X X . | $$ | . . . . . . O O X X X O X O 7 O X O . | $$ | . O O . O O X O O . . . 6 . 1 X O . O | $$ | . O X . . X X . O X X O . O O . O O . | $$ | O X X X . . . X O O X X O X O , O . . | $$ | . O O X . X X . O . O X . X X X O . . | $$ | . . . . X O O X O . O X . . . O 5 O . | $$ | . . . . . X . . . . . . . . . X 2 X . | $$ ---------------------------------------[/go]
I will post some variations next.
Re: 3 L&D problems from an ancient Chinese game
Posted: Fri Dec 31, 2010 8:16 pm
by hiyayang
Assessment of the situation:
$$Bc Moves 158 and 159 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . X X . X X . X O . O . X . . . . O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . . . f . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . O . X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X . . | $$ | . . . . . . O O X X X O X O . O X b . | $$ | . O O . O O X . O . . . a . . X O X . | $$ | . O X . . X X . O X X O . O O . O O . | $$ | O X X X . . . X O O X X O X O , O . . | $$ | . O O X . X X . O . O X . X X X O . . | $$ | . . e . X O O c d . O X . . . . 1 2 . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------
[go]$$Bc Moves 158 and 159 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . X X . X X . X O . O . X . . . . O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . . . f . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . O . X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X . . | $$ | . . . . . . O O X X X O X O . O X b . | $$ | . O O . O O X . O . . . a . . X O X . | $$ | . O X . . X X . O X X O . O O . O O . | $$ | O X X X . . . X O O X X O X O , O . . | $$ | . O O X . X X . O . O X . X X X O . . | $$ | . . e . X O O c d . O X . . . . 1 2 . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]
It has already been hinted that W 'a' is sente, forcing B 'b'. In addition, W 'c' or 'd' is sente, forcing B 'e'. OTOH, B 'c' is also sente, forcing W 'd' (and then H6 when B puts the two white stones in atari). And B has to watch out for the cut at 'f'.
With these in mind, you will see that B's options to live the LR group without getting his other groups killed are really limited, hence .
Re: 3 L&D problems from an ancient Chinese game
Posted: Fri Dec 31, 2010 9:39 pm
by hiyayang
Black failure #1:
Trying to live without ko, B ends up getting his group killed --
$$Bc Black group dies $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . X X . X X . X O . O . X . . . . O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . O . X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X . . | $$ | . . . . . . O O X X X O X O . O X 3 . | $$ | . O O . O O X . O . . . 2 . . X O X . | $$ | . O X . . X X . O X X O d O O . O O . | $$ | O X X X . . . X O O X X O X O , O . . | $$ | . O O X . X X . O . O X c X X X O . . | $$ | . . . . X O O . b . O X . . 9 6 X O . | $$ | . . . . . . . . . . a 0 e 8 5 7 1 4 . | $$ ---------------------------------------
[go]$$Bc Black group dies $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . X X . X X . X O . O . X . . . . O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . O . X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X . . | $$ | . . . . . . O O X X X O X O . O X 3 . | $$ | . O O . O O X . O . . . 2 . . X O X . | $$ | . O X . . X X . O X X O d O O . O O . | $$ | O X X X . . . X O O X X O X O , O . . | $$ | . O O X . X X . O . O X c X X X O . . | $$ | . . . . X O O . b . O X . . 9 6 X O . | $$ | . . . . . . . . . . a 0 e 8 5 7 1 4 . | $$ ---------------------------------------[/go]
Note:
1. B 'a' is not sente (because W 'b' is), otherwise W would be unable to go home.
2. It is important that B 'c' does not force W 'd', otherwise B could throw in at 'e' to live. Therefore, W has to be careful with , as he would get an inferior result by playing this way:
$$Bc White fails $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . X X . X X . X O . O . X . . . . O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . O . X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X 3 . | $$ | . . . . . . O O X X X O X O . O X 2 . | $$ | . O O . O O X . O . . . 6 7 5 X O X 4 | $$ | . O X . . X X . O X X O b O O . O O . | $$ | O X X X . . . X O O X X O X O , O . . | $$ | . O O X . X X . O . O X a X X X O . . | $$ | . . . . X O O . . . O X . . . . X O . | $$ | . . . . . . . . . . . . c . 9 . 1 8 . | $$ ---------------------------------------
[go]$$Bc White fails $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . X X . X X . X O . O . X . . . . O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . O . X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X 3 . | $$ | . . . . . . O O X X X O X O . O X 2 . | $$ | . O O . O O X . O . . . 6 7 5 X O X 4 | $$ | . O X . . X X . O X X O b O O . O O . | $$ | O X X X . . . X O O X X O X O , O . . | $$ | . O O X . X X . O . O X a X X X O . . | $$ | . . . . X O O . . . O X . . . . X O . | $$ | . . . . . . . . . . . . c . 9 . 1 8 . | $$ ---------------------------------------[/go]
Later B 'a' would enable a ko at 'b' or a throw-in at 'c' as described above.
Re: 3 L&D problems from an ancient Chinese game
Posted: Sat Jan 01, 2011 3:42 pm
by hiyayang
Variation #1:
So double hane to live with ko is the best result B can hope for in this situation.
Now W has a choice. If W avoids the ko, B lives:
$$Bc White backs off; Black lives $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . X X . X X . X O . O . X . . . . O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . . . f . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . O . X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X . . | $$ | . . . . . . O O X X X O X O . O X 5 . | $$ | . O O . O O X . O . . . 4 . . X O X . | $$ | . O X . . X X . O X X O . O O . O O . | $$ | O X X X . . . X O O X X O X O , O . . | $$ | . O O X . X X . O . O X 9 X X X O 2 . | $$ | . . . . X O O . . . O X 8 a . . X O . | $$ | . . . . . . . . . . . 6 7 0 3 . . 1 . | $$ ---------------------------------------
[go]$$Bc White backs off; Black lives $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . X X . X X . X O . O . X . . . . O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . . . f . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . O . X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X . . | $$ | . . . . . . O O X X X O X O . O X 5 . | $$ | . O O . O O X . O . . . 4 . . X O X . | $$ | . O X . . X X . O X X O . O O . O O . | $$ | O X X X . . . X O O X X O X O , O . . | $$ | . O O X . X X . O . O X 9 X X X O 2 . | $$ | . . . . X O O . . . O X 8 a . . X O . | $$ | . . . . . . . . . . . 6 7 0 3 . . 1 . | $$ ---------------------------------------[/go]
Then B 'a' lives.
But why should W be afraid of the ko fight? He has virtually nothing to lose here -- even if B won the ko fight, the W group in the LR corner is still alive:
$$B Moves 190 to 191 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . 2 . . . . | $$ | . X X . X X . X O . O . X . . . O O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . O . X . X O X O . O X . | $$ | . . . , O . X O O X X X X X O O X X . | $$ | . . . . . . X X O b X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X X . | $$ | . . . . . . O O X X X O . O a O X O . | $$ | . O O . O O X O O . . . O B X X O . O | $$ | . O X . . X X . O X X O . O O . O O c | $$ | O X X X . . . X O O X X O X O , O . d | $$ | . O O X . X X . O . O X . X X X O 3 4 | $$ | . . . . X O O X O . O X . . 1 O X O . | $$ | . . . . . X . . . . . . . . . X . X . | $$ ---------------------------------------
[go]$$B Moves 190 to 191 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . 2 . . . . | $$ | . X X . X X . X O . O . X . . . O O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . O . X . X O X O . O X . | $$ | . . . , O . X O O X X X X X O O X X . | $$ | . . . . . . X X O b X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X X . | $$ | . . . . . . O O X X X O . O a O X O . | $$ | . O O . O O X O O . . . O B X X O . O | $$ | . O X . . X X . O X X O . O O . O O c | $$ | O X X X . . . X O O X X O X O , O . d | $$ | . O O X . X X . O . O X . X X X O 3 4 | $$ | . . . . X O O X O . O X . . 1 O X O . | $$ | . . . . . X . . . . . . . . . X . X . | $$ ---------------------------------------[/go]
That is, even if W got cut at 'b' and B played the circled stone (to destroy W's eye) instead of the actual game move 'a' (to give W fewer ko threats). Then, whether B plays or 'd', secures the eye at 'c'.
W just has to make sure he gets compensated elsewhere for the loss of the ko fight.
Re: 3 L&D problems from an ancient Chinese game
Posted: Sat Jan 01, 2011 4:12 pm
by hiyayang
Black failure #2:
Point wise, fighting the ko in the center is less advantageous for B than in the corner:
$$Bc After move 157 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . X X . X X . X O . O . X . . . . O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . O . X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X . . | $$ | . . . . . . O O X X X O X O . O X 7 . | $$ | . O O . O O X . O 9 8 1 2 . . X O X . | $$ | . O X . . X X . O X X 6 3 O O . O O . | $$ | O X X X . . . X O O X X O X O , O . . | $$ | . O O X . X X . O . O X . X X X O . . | $$ | . . 5 . X O O . 4 . O X . . . 0 . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------
[go]$$Bc After move 157 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . X X . X X . X O . O . X . . . . O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . O . X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X . . | $$ | . . . . . . O O X X X O X O . O X 7 . | $$ | . O O . O O X . O 9 8 1 2 . . X O X . | $$ | . O X . . X X . O X X 6 3 O O . O O . | $$ | O X X X . . . X O O X X O X O , O . . | $$ | . O O X . X X . O . O X . X X X O . . | $$ | . . 5 . X O O . 4 . O X . . . 0 . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]
Re: 3 L&D problems from an ancient Chinese game
Posted: Sat Jan 01, 2011 4:30 pm
by hiyayang
Variation #2:
In previous diagram, W has to be careful with the ko threat . For example, I don't think in the following diagram would work out for W:
$$Bc After move 157 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . X X . X X . X O . O . X . . . . O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . W 5 X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X . . | $$ | . . . . . . O O X X X O 6 O 4 O X 7 . | $$ | . O O . O O X . O . . 1 2 . . X O X . | $$ | . O X . . X X . O X X O 3 O O . O O . | $$ | O X X X . . . X O O X X O X O , O . . | $$ | . O O X . X X . O . O X . X X X O . . | $$ | . . . . X O O . . . O X . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------
[go]$$Bc After move 157 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . X X . . . . . . . . . . . | $$ | . X X . X X . X O . O . X . . . . O . | $$ | . . O , X . . X . , . . . . X X . X X | $$ | . X . O O X X X O . O . X X O . X O . | $$ | . . . . . O O O . O X X . O O . O O . | $$ | . . . X O . . . . X X . O . . . . . . | $$ | . . . . . . . . . X O O . O O . O X . | $$ | . . X . O . . . . . . X O X O . O X . | $$ | . . . , . . . . . X X X X X O O X X . | $$ | . . . . . . . . W 5 X X O O X O O X . | $$ | . O X . . O . X X O O O O X X X X . . | $$ | . . . . . . O O X X X O 6 O 4 O X 7 . | $$ | . O O . O O X . O . . 1 2 . . X O X . | $$ | . O X . . X X . O X X O 3 O O . O O . | $$ | O X X X . . . X O O X X O X O , O . . | $$ | . O O X . X X . O . O X . X X X O . . | $$ | . . . . X O O . . . O X . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]
The problem with this is that it allows B to cut in sente ( ). As a result, the marked white stone would have to run in gote.
—the ladder doesn't work. 
at 
, to the same effect. Actually, there is a bonus question derived from this:
seems to work:
?
would be unable to go home.
or 'd', 
secures the eye at 'c'.
). As a result, the marked white stone would have to run in gote.