Passive ko rule

Mef · Post by **Mef** » Fri Sep 14, 2012 4:22 pm

luigi wrote:If your opponent has captured n stones on his turn, you can't make a capture on your next n turns.

This rule needs slight modification to deal with one player capturing on consecutive turns. A contrived example:

Click Here To Show Diagram Code: [go]$$B Four x send 3 return 1 $$ -------------------- $$ | X X O O O . O . O| $$ | . X X X X O O O O| $$ | X X . . X O . O X| $$ | . X X X X O . O X| $$ | X O O O X O O O X| $$ | X O . O X X X X .| $$ | X O . O X . . X X| $$ | O O O O X X X X .| $$ | O . O . O O O X X| $$ --------------------[/go]

Click Here To Show Diagram Code: [go]$$B Cooperative cycle B5, 7, 9 are pass $$ -------------------- $$ | X X 8 6 . 3 O . O| $$ | . X X X X O O O O| $$ | X X . . X O . O X| $$ | 0 X X X X O . O X| $$ | X O O O X O O O X| $$ | X O . O X X X X .| $$ | X O . O X . . X X| $$ | O O O O X X X X .| $$ | O . O 1 . 2 4 X X| $$ --------------------[/go]

B captures at 1 (W cannot capture for 3 moves), W2 (2 moves), B captures at 3 (W cannot capture for 3 moves), W4, 6, 8 remove the capture ban. 10 means B cannot capture for 3 moves.

Click Here To Show Diagram Code: [go]$$Bm11 Cycle completes W18, 20 are pass, B21 marked $$ -------------------- $$ | X X O O 4 X O . O| $$ | . X X X X O O O O| $$ | X X . . X O . O 7| $$ | O X X X X O . O 5| $$ | B O O O X O O O 9| $$ | 1 O . O X X X X 2| $$ | 3 O . O X . . X X| $$ | O O O O X X X X .| $$ | O . O X 6 O O X X| $$ --------------------[/go]

After 12, B can't play for 3 moves, W captures at 14 and 16, but those don't increase the length of the capture ban. B21 gets us back to the original position.

If you reword the rule to track of the total number of moves a player cannot play (add them together in the case of consecutive capture) it would prevent cycles for certain.

luigi · Post by **luigi** » Sat Sep 15, 2012 8:16 am

Mef wrote:If you reword the rule to track of the total number of moves a player cannot play (add them together in the case of consecutive capture) it would prevent cycles for certain.

Yes, you're right. Actually that's what I was trying to say, but I didn't realize that my oversimplified wording didn't convey that meaning.

When I tested this idea, I had captured pieces put in a cumulative "reserve" next to the board. At the start of a player's turn, if there were any stones of his color in the reserve, he had to pass or use a stone from the reserve to make a non-capturing move on the board, after which his turn ended.

That would be the proper wording.

luigi · Post by **luigi** » Wed Sep 19, 2012 7:33 am

luigi wrote:As a curiosity, either of the following similar rules would make cycles mathematically impossible:

If your opponent has captured n stones on his turn, you can't make a capture on your next n turns. (EDIT: Further stones captured by the opponent are added to n.)

If your opponent has captured n stones on his turn, neither player can make a capture until the total number of non-capturing moves played afterwards equals n.

These rules would change the game completely, but they could be interesting experiments anyway. I suspect the first one would give far too much of an incentive to make captures, but the second one should be more balanced.

There's of course a third alternative:

If you capture n stones on your turn, you can't make a capture again on your next n turns.

This has some curious implications regarding ko.

Also, in all three versions, instead of banning capturing moves, you can allow them but not let players remove the surrounded stones until n is 0.

skydyr · Post by **skydyr** » Wed Sep 19, 2012 8:10 am

luigi wrote:Also, in all three versions, instead of banning capturing moves, you can allow them but not let players remove the surrounded stones until n is 0.

Does this mean that the capture of, say, a 20-stone group could be prevented by capturing and removing a 4-stone group surrounding it before the 20 turn wait expires? Because my head just broke

badukJr · Post by **badukJr** » Wed Sep 19, 2012 5:36 pm

So basically anyone losing a capturing race can delay it and huge swaths of the board will become empty as both groups are simultaneously removed from the board when the ban is up.

Sounds Crazy.

luigi · Post by **luigi** » Thu Sep 20, 2012 12:05 am

skydyr wrote:
luigi wrote:Also, in all three versions, instead of banning capturing moves, you can allow them but not let players remove the surrounded stones until n is 0.

Does this mean that the capture of, say, a 20-stone group could be prevented by capturing and removing a 4-stone group surrounding it before the 20 turn wait expires? Because my head just broke

Well, I guess it could be interpreted that way, but, actually, what I meant is that you can't capture if n > 0 because of an earlier capture. So, for example, if you're using the first rule I suggested, i.e:

If your opponent has captured n stones on his turn, you can't make a capture on your next n turns. Further stones captured by the opponent are added to n.

Then it means that if you have a 20-stone group in atari, you can prevent its capture by capturing, say, an enemy 4-stone group and then capturing one of the enemy groups surrounding your 20-stone group within your next 4 moves, just as before, with the difference that your opponent is allowed to occupy the last liberty of your group, without removing it, before the ban is up.

luigi · Post by **luigi** » Thu Sep 20, 2012 12:07 am

badukJr wrote:So basically anyone losing a capturing race can delay it and huge swaths of the board will become empty as both groups are simultaneously removed from the board when the ban is up.

Sounds Crazy.

Indeed! Crazily fun.

Mef · Post by **Mef** » Mon Sep 24, 2012 4:26 pm

luigi wrote:If you capture n stones on your turn, you can't make a capture again on your next n turns.

This has some curious implications regarding ko.

This actually has an interesting effect on Big-eye vs. One eye capturing races (amongst many other situations where you have multiple capturing races on the board simultaneously)...if you capture an almost filled big-eye you cannot capture again until that eye has been almost filled again, so big eye provides no extra liberties!

Kanin · Post by **Kanin** » Tue Sep 25, 2012 8:21 am

Someone please make an online playground where we can play with these funny rules. I would love to try them out. Sorry for just asking, I'm no programmer myself.

hyperpape · Post by **hyperpape** » Tue Sep 25, 2012 9:33 am

I think iggamecenter has a sandbox feature that game-designers often use.

cyclops · Post by **cyclops** » Thu Sep 27, 2012 5:22 pm

For another ko-rule:
Capturing a single stone is forbidden if it is a self atari and the capturing stone is not attaching to any friendly stone.

jts · Post by **jts** » Thu Sep 27, 2012 8:55 pm

cyclops wrote:For another ko-rule:
Capturing a single stone is forbidden if it is a self atari and the capturing stone is not attaching to any friendly stone.

That makes false eyes unfillable, no?

luigi · Post by **luigi** » Fri Sep 28, 2012 11:42 am

hyperpape wrote:I think iggamecenter has a sandbox feature that game-designers often use.

Yes, I use it a lot to test my own and other people's games. I'd gladly test passive ko or its variants there someday with anyone interested.

cyclops · Post by **cyclops** » Fri Sep 28, 2012 5:06 pm

jts wrote:
cyclops wrote:For another ko-rule:
Capturing a single stone is forbidden if it is a self atari and the capturing stone is not attaching to any friendly stone.

That makes false eyes unfillable, no?

Yes, at least some. Maybe the game is boring because living becomes easier.

For yet another ko-rule:
Capturing a single stone is allowed but if it is a self atari and the capturing stone is not attaching to any friendly stone the captured stone is replaced by a stone of the capturer.

luigi · Post by **luigi** » Sun Jan 06, 2013 9:38 pm

I've added this to my original post:

luigi wrote:EDIT:

The following rule preserves snapbacks while still preventing all known cycles:

If your opponent has captured n stones on his previous turn, you can't make a capture on your turn unless it's bigger than n stones.

How does that look?

Life In 19x19

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