Life In 19x19 :: Counting point, weird loop

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Counting point, weird loop http://www.lifein19x19.com/viewtopic.php?f=4&t=9706	Page 1 of 1

Author: m4la [ Fri Jan 17, 2014 9:07 am ]

Post subject: Counting point, weird loop

hi everyone,
it's my first post here and i hope i choose the right section (if not please forgive me :bow:

)

I'm new to the game, and i'm still having problem sometimes in understanding who's getting the territory, so often i ends up playing groups till they're obviously and undoubtedly dead (you would probably declare them dead 10 moves ahead).

Yesterday i found a weird loop at the end of the game and i have no idea how to count points in that situation.

Click Here To Show Diagram Code: [go]$$Wcm31 Given the whole board set \n here's the situation in the bottom left $$B corner $$ | . . . . . . . . . $$ | . . . . . . . . . $$ | X X X . . . . . . $$ | O O X X X X . . . $$ | . O O O O X . . . $$ | . O . O X X . . . $$ | O X X O O X . . . $$ ------------------[/go]

Click Here To Show Diagram Code: [go]$$Wcm31 Now black capture \n and white pass $$B corner $$ | . . . . . . . . . $$ | . . . . . . . . . $$ | X X X . . . . . . $$ | O O X X X X . . . $$ | . O O O O X . . . $$ | B O . O X X . . . $$ | . X X O O X . . . $$ ------------------[/go]

Click Here To Show Diagram Code: [go]$$Wcm31 Atari $$B corner $$ | . . . . . . . . . $$ | . . . . . . . . . $$ | X X X . . . . . . $$ | O O X X X X . . . $$ | B O O O O X . . . $$ | X O . O X X . . . $$ | . X X O O X . . . $$ ------------------[/go]

Click Here To Show Diagram Code: [go]$$Wcm31 and we're back at the same position as fig. 1 $$B corner $$ | . . . . . . . . . $$ | . . . . . . . . . $$ | X X X . . . . . . $$ | O O X X X X . . . $$ | . O O O O X . . . $$ | . O . O X X . . . $$ | W X X O O X . . . $$ ------------------[/go]

What is that? Seki? a sort of ko?
is there a way to end the fight and establish who's the winner?

Thanks for your attention :tmbup:

Author:	emeraldemon [ Fri Jan 17, 2014 9:13 am ]
Post subject:	Re: Counting point, weird loop
Black can connect instead of atari to create a seki. The shape you have is a long ko cycle, which unfortunately is handled differently in different rulesets. Look up sending 2 returning 1 on sensei's library.

Author:	leichtloeslich [ Fri Jan 17, 2014 10:12 am ]
Post subject:	Re: Counting point, weird loop
Hm, I always considered this seki, because under territory scoring every iteration of the loop gives one prisoner to white, so white can eventually give up the group after having gotten enough prisoners in return. So there's no endless cycle here. In area scoring every iteration of the loop still costs black sente: the loop starts with black to play and ends with white to play while gaining nothing for black. So this could only possibly be an issue at the very end of the game in area scoring without any superko rule.

Author: Bill Spight [ Fri Jan 17, 2014 12:05 pm ]

Post subject: Re: Counting point, weird loop

Click Here To Show Diagram Code: [go]$$Wc Seki $$ | . . . . . . . . . $$ | . . . . . . . . . $$ | X X X . . . . . . $$ | O O X X X X . . . $$ | . O O O O X . . . $$ | B O . O X X . . . $$ | . X X O O X . . . $$ ------------------[/go]

As a final position, this is seki in all modern rule sets in common use.

Click Here To Show Diagram Code: [go]$$Wc White first $$ | . . . . . . . . . $$ | . . . . . . . . . $$ | X X X . . . . . . $$ | O O X X X X . . . $$ | 1 O O O O X . . . $$ | B O 2 O X X . . . $$ | . X X O O X . . . $$ ------------------[/go]

Obviously, White cannot afford to approach Black.

Click Here To Show Diagram Code: [go]$$Bc Black first $$ | . . . . . . . . . $$ | . . . . . . . . . $$ | X X X . . . . . . $$ | O O X X X X . . . $$ | 1 O O O O X . . . $$ | B O . O X X . . . $$ | 2 X X O O X . . . $$ ------------------[/go]

Black to play can approach White, but after three moves has made not headway, and has lost two stones to White's one stone. This is called Sending Two, Returning One.

Under Japanese and Korean rules, Black loses one point every time he repeats that sequence, so he does not do it. If he keeps it up, eventually White can afford to let him capture the corner.

Under Chinese and AGA rules, which count stones on the board instead of counting prisoners, Black loses nothing from playing that sequence, and they have different ways of preventing Black from doing so repeatedly.

Author:	DrStraw [ Fri Jan 17, 2014 5:01 pm ]
Post subject:	Re: Counting point, weird loop
Were you playing Igowin? It plays this way at the end of the game frequently. As others have said, B cannot win and all W needs to do is go through the iteration enough time to get the points to compensate losing the group and then give up. Either way, W wins.

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