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 Post subject: Re: GT territory rule
Post #81 Posted: Wed Aug 25, 2021 3:07 pm 
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Gérard TAILLE wrote:
jann wrote:
Click Here To Show Diagram Code
[go]$$B
$$ +---------------------------------+
$$ | O O O O O X O O . X . O O X X X |
$$ | O O O O . X O O O X O O O X . O |
$$ | O O O O O X O . O X O . O X O . |
$$ | O O O O . X O O O X O O O X X O |
$$ | O O O O O X O O O X O O O X . . |
$$ +---------------------------------+
$$[/go]

W claims a chunk of territory in the center with middle B string (the one between symmetric W groups) dead. Inner and outer borders are OK and W can, even with B starting, take pass-alive control of that part of the board and capture 5 stones. Right?

BTW Jann, why not having "simply" use the following position:
Click Here To Show Diagram Code
[go]$$B
$$ +---------------------------+
$$ | O O X O O . X . O O X X X |
$$ | O . X O O O X O O O X . O |
$$ | O O X O . O X O . O X O . |
$$ | O . X O O O X O O O X X O |
$$ | O O X O O O X O O O X . . |
$$ +---------------------------+
$$[/go]
with the same result?

Yes Jann I agree with you, white can claim for a territory in the center. This position looks a seki in J2003 and this seki result seems more in the spirit of japonese rule. Agreed.

Let me try to understand the issue.

Your first question could explain the second. W's left is big to make sure W never want to actually use that in ko threat (small left may worth throwing away in game).

The position is not seki because of anything wrt J2003 - it is seki by general Japanese (or general go) logic. W cannot do anything in reality since going for the capture would be disadvantageous (cost much higher than the gain). LD analysis should reflect go reality (which is same under Chinese rule).

jann wrote:
The problem with the approach of this thread - as opposed to big sister LJRG - seems to be allowing global play without looking at global consequences.

This allows confirmation results very different from real go outcomes (no "enable" like J89, so W can play lines he would never in reality - since consequences ignored).

BTW you should always try to look at the logic behind rules (examples come later, nitpicking on wordings lastly / never). Go has centuries of history, the concepts and cohesive logic in real, widely used rules are simple and somewhat robust (even if modern formalizations aren't yet).

For others: W not claimed anything about left B string, only the middle one.

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 Post subject: Re: GT territory rule
Post #82 Posted: Wed Aug 25, 2021 5:28 pm 
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Cassandra wrote:
Mike Novack wrote:
However the other group of five black stones remains alive in seki.

Once White has taken Black's right-hand group off the board, the seki will be resolved completely from right to left.

As I already mentioned earlier several times, painting diagrams would help a lot :D


No, the leftmost string of five black stones remains alive in seki with the white group to its left (there are two dame between these groups)

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 Post subject: Re: GT territory rule
Post #83 Posted: Wed Aug 25, 2021 7:26 pm 
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Mike Novack wrote:
Cassandra wrote:
Mike Novack wrote:
However the other group of five black stones remains alive in seki.

Once White has taken Black's right-hand group off the board, the seki will be resolved completely from right to left.

As I already mentioned earlier several times, painting diagrams would help a lot :D


No, the leftmost string of five black stones remains alive in seki with the white group to its left (there are two dame between these groups)

As I said, painting diagrams would help a lot :D

And / or explaining a little, little bit move in detail.

Please excuse my blind spot, but sometimes I am blind in all eyes. Especially when other topics are circling around in the container that was made for these.

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 Post subject: Re: GT territory rule
Post #84 Posted: Thu Aug 26, 2021 7:29 am 
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Click Here To Show Diagram Code
[go]$$B
$$ -----------------
$$ | O X . X . O . |
$$ | . O X X X O O |
$$ | O . O O X X O |
$$ | O O O . O X O |
$$ | X X O O X X O |
$$ | . X X O O O . |
$$ | X . X X X O O |
$$ -----------------[/go]

How works GT territory rule in the now well known above example.

Click Here To Show Diagram Code
[go]$$B
$$ -----------------
$$ | W B C B C W C |
$$ | C W B B B W W |
$$ | W C W W B B W |
$$ | W W W C W B W |
$$ | X X W W B B W |
$$ | . X X W W W C |
$$ | X . X X X W W |
$$ -----------------[/go]


White claim for controlling the marked area above.
Borders are OK => An hypothetical play will begin with black to play first and white trying to build a two-eye formation covering all the marked area

Click Here To Show Diagram Code
[go]$$B :b5: pass, :b7: pass
$$ -----------------
$$ | 4 X 6 X . O . |
$$ | 1 O X X X O O |
$$ | O 2 O O X X O |
$$ | O O O 3 O X O |
$$ | X X O O X X O |
$$ | . X X O O O . |
$$ | X . X X X O O |
$$ -----------------[/go]
note that the move :w4: is here allowed because normal play is used in confirmation phase.

Click Here To Show Diagram Code
[go]$$Bm7 :b9: pass
$$ -----------------
$$ | O 2 O X 4 O . |
$$ | . O X X X O O |
$$ | O . O O X X O |
$$ | O O O X . X O |
$$ | X X O O X X O |
$$ | . X X O O O . |
$$ | X . X X X O O |
$$ -----------------[/go]

and it is clear white will mange to build a two-eye formation on all the claimed area => white controlled the claimed are => white has a territory in it

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 Post subject: Re: GT territory rule
Post #85 Posted: Fri Aug 27, 2021 5:52 am 
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jann wrote:
Your first question could explain the second. W's left is big to make sure W never want to actually use that in ko threat (small left may worth throwing away in game).

The position is not seki because of anything wrt J2003 - it is seki by general Japanese (or general go) logic. W cannot do anything in reality since going for the capture would be disadvantageous (cost much higher than the gain). LD analysis should reflect go reality (which is same under Chinese rule).

jann wrote:
The problem with the approach of this thread - as opposed to big sister LJRG - seems to be allowing global play without looking at global consequences.

This allows confirmation results very different from real go outcomes (no "enable" like J89, so W can play lines he would never in reality - since consequences ignored).

BTW you should always try to look at the logic behind rules (examples come later, nitpicking on wordings lastly / never). Go has centuries of history, the concepts and cohesive logic in real, widely used rules are simple and somewhat robust (even if modern formalizations aren't yet).

For others: W not claimed anything about left B string, only the middle one.


Your comments sound quite interesting but I have difficulties to understand what is really your understanding of this general Japanese (or general go) logic.
In chinese GO the logic is clear, and because there are no confirmation phase at all, the same logic applies till the very end of the game. In that sense chinese GO is perfect.
In japanese GO the logic is not as clear, though japanese GO has been played for centuries ;-). The issue is that when game stops by agreement after "normal play" it is difficult to resolve the dispute by just using normal play.
In order for me to really understand your comment, can you show how you apply this japanese GO logic in the three following very common examples:

Click Here To Show Diagram Code
[go]$$W three kos but one is external
$$ -----------------
$$ | . X X X X X X |
$$ | X X . X O X X |
$$ | O O X O . O O |
$$ | . O O O O O O |
$$ | O X X X X X X |
$$ | X X . . . X . |
$$ | . . . . . X . |
$$ -----------------[/go]


Click Here To Show Diagram Code
[go]$$B moonshine life
$$ ---------------------
$$ | . . . X O X . X . |
$$ | . . . X O O X X X |
$$ | . . . X O . O X O |
$$ | . . . X O O O O . |
$$ | . . . X X X X O O |
$$ | . . . . . . X X X |
$$ | X X X X . . . . . |
$$ | O O O X X . . . . |
$$ | . O . O X . . . . |
$$ ---------------------[/go]


Click Here To Show Diagram Code
[go]$$B bent four and ko threat in a seki
$$ ---------------------
$$ | O O O . X O . . . |
$$ | . X X X X O . . . |
$$ | X X O O O O . . . |
$$ | O O O O . . . . . |
$$ | . . . . . . . . . |
$$ | . . . . . . . . . |
$$ | X X X X X X X . . |
$$ | O O O O O O X . . |
$$ | . X X X . O X . . |
$$ ---------------------[/go]

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 Post subject: Re: GT territory rule
Post #86 Posted: Fri Aug 27, 2021 6:34 am 
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Gérard TAILLE wrote:
Your comments sound quite interesting but I have difficulties to understand what is really your understanding of this general Japanese (or general go) logic.
In chinese GO the logic is clear, and because there are no confirmation phase at all, the same logic applies till the very end of the game. In that sense chinese GO is perfect.
In japanese GO the logic is not as clear, though japanese GO has been played for centuries ;-). The issue is that when game stops by agreement after "normal play" it is difficult to resolve the dispute by just using normal play.

Yes. But we know Japanese go and Chinese go are closely tied to each other. So there must not be any outrageously large differences in outcomes. And even in Japanese go you can imagine what would happen if the game would continue (ignoring the small potential score drift caused by unanswered cleanup moves - or using pass stones). In my above example, there is no doubt about the correct ruling - Japanese and Chinese go agree (as is usually the case).

Quote:
In order for me to really understand your comment, can you show how you apply this japanese GO logic in the three following very common examples

Moonshine life is one particular case (maybe the only one) where the basic rules logic may not be sufficient. But note this is NOT specific to Japanese go but also the same in Chinese go!

The question is, of course, the logical difference between real triple ko (which is draw in both Japanese and Chinese) and moonshine kos (which treatment varied a bit in history but the current consensus is that it is dead). Several interesting ideas appeared about this in the past, you can find reference material on usenet and elsewhere if interested.

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 Post subject: Re: GT territory rule
Post #87 Posted: Fri Aug 27, 2021 7:21 am 
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jann wrote:
Gérard TAILLE wrote:
Your comments sound quite interesting but I have difficulties to understand what is really your understanding of this general Japanese (or general go) logic.
In chinese GO the logic is clear, and because there are no confirmation phase at all, the same logic applies till the very end of the game. In that sense chinese GO is perfect.
In japanese GO the logic is not as clear, though japanese GO has been played for centuries ;-). The issue is that when game stops by agreement after "normal play" it is difficult to resolve the dispute by just using normal play.

Yes. But we know Japanese go and Chinese go are closely tied to each other. So there must not be any outrageously large differences in outcomes. And even in Japanese go you can imagine what would happen if the game would continue (ignoring the small potential score drift caused by unanswered cleanup moves - or using pass stones). In my above example, there is no doubt about the correct ruling - Japanese and Chinese go agree (as is usually the case).

Quote:
In order for me to really understand your comment, can you show how you apply this japanese GO logic in the three following very common examples

Moonshine life is one particular case (maybe the only one) where the basic rules logic may not be sufficient. But note this is NOT specific to Japanese go but also the same in Chinese go!

The question is, of course, the logical difference between real triple ko (which is draw in both Japanese and Chinese) and moonshine kos (which treatment varied a bit in history but the current consensus is that it is dead). Several interesting ideas appeared about this in the past, you can find reference material on usenet and elsewhere if interested.


OK let's put aside triple ko and moonshine and their loop handling.

How do you apply the japanese logic to bent four in the corner beside an unremovable ko threat in a seki?

Click Here To Show Diagram Code
[go]$$B bent four in the corner and ko threat in a seki
$$ ---------------------
$$ | O O O . X O . . . |
$$ | . X X X X O . . . |
$$ | X X O O O O . . . |
$$ | O O O O . . . . . |
$$ | . . . . . . . . . |
$$ | . . . . . . . . . |
$$ | X X X X X X X . . |
$$ | O O O O O O X . . |
$$ | . X X X . O X . . |
$$ ---------------------[/go]

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 Post subject: Re: GT territory rule
Post #88 Posted: Fri Aug 27, 2021 7:48 am 
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Gérard TAILLE wrote:
How do you apply the japanese logic to bent four in the corner beside an unremovable ko threat

Bent4 is less interesting for rule theory. Japanese invented local L/D, partly as an attempt to fix moonshine life. A doubtful hack IMO but is deeply rooted in Japanese minds now. And once they went this route bent4 become dead even with unremovable threats. Not good but in itself not unacceptably bad either. Just for fun you can also try this example in J89 with enable but without pass for ko.


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 Post subject: Re: GT territory rule
Post #89 Posted: Fri Aug 27, 2021 8:23 am 
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jann wrote:
Gérard TAILLE wrote:
How do you apply the japanese logic to bent four in the corner beside an unremovable ko threat

Bent4 is less interesting for rule theory. Japanese invented local L/D, partly as an attempt to fix moonshine life. A doubtful hack IMO but is deeply rooted in Japanese minds now. And once they went this route bent4 become dead even with unremovable threats. Not good but in itself not unacceptably bad either. Just for fun you can also try this example in J89 with enable but without pass for ko.

I begin to understand your view Jann.
Maybe I am wrong but let'try:
Assume I take Bill Spight "encore" and,
Assume I modify this "encore" by replacing the pass-ko rule by my "permanently prohibited ko" in order to handle loops according to japanese traditions, and
Assume finally I manage to take care of unsided dame which cause some problems with "encore" relatively to the seki in japanese rule (it is not that difficult to do indeed)
Isn't it exactly the perfect japonese rule you have in mind?

In this "perfect rule" you can note OC that bent four in the corner is not uncondionnaly dead if unremovable ko threat exists (it will be a good point for you won't it?)

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 Post subject: Re: GT territory rule
Post #90 Posted: Fri Aug 27, 2021 10:32 am 
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For the time being two positions are an issue for my "GT territory rule".

Firstly the following position I analysed in https://lifein19x19.com/viewtopic.php?p=266754#p266754

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

I concluded in "GT territory rule" that black has a territory in the upper right corner though a seki seems more appropriate.

And secondly the position found by Jann and showed in https://lifein19x19.com/viewtopic.php?p=266868#p266868

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

Here "GT territory rule" concludes to territory though a seki seems more appropriate.

Two positions is already too many isn't?
That means that I missed something. I think the problem is exactly the same for these two positions:

Click Here To Show Diagram Code
[go]$$B
$$ -----------------
$$ | . W X X . O X |
$$ | . . W X . O X |
$$ | . . W X X O X |
$$ | . . W W W X X |
$$ | . . . . W X . |
$$ | . . . . W X X |
$$ | . . . . W X . |
$$ | . . . . W X X |
$$[/go]
If in the first position you assume that the outside border is independantly alive then black cannot anymore kill the three white stones

Click Here To Show Diagram Code
[go]$$B
$$ +---------------------------------+
$$ | . . . . . B O O . X . O O B . . |
$$ | . . . . . B O O O X O O O B . . |
$$ | . . . . . B O . O X O . O B . . |
$$ | . . . . . B O O O X O O O B . . |
$$ | . . . . . B O O O X O O O B . . |
$$ +---------------------------------+
$$[/go]
Similarly if in this second position you assume that the outside border is independantly alive white cannot anymore kill the five black stones.

IOW to be a territory need one more condition.

I propose the following improvement to my draft rule (see points 3 and 4 under):

A set of locations is a "controlled area" for a player if:
1) The inside border contains neither empty locations nor stones of the opponent.
2) The outside border contains neither empty locations nor stones of the player.
3) the set of locations can be entirely covered by a "two-eye formation" through an hypthetical play (see below) played only on the "controlled area", assuming the outside border independantly alive
4) the set of locations can be entirely covered by a "two-eye formation" through an hypthetical play (see below) played on all the board


Comment1 : in 99% of cases the sequence found in 3) works also for 4) but in rare cases 3) and 4) might be independant.
Comment2 : due to comment1 (!) I did not see any impact on all other examples I presented here

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 Post subject: Re: GT territory rule
Post #91 Posted: Fri Aug 27, 2021 11:45 am 
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Gérard TAILLE wrote:
Isn't it exactly the perfect japonese rule you have in mind?

it's much easier to recognize something wrong (logical flaws or violating important principles) than talking about "perfect" rules.

You also seem to overestimate the extent of acceptable complexity of go rules. Even a single hack like pass stones or pass for ko is borderline, bigger and more (like 2-3 complicated inventions at the same time) are too much. And the more you use the more likely those lack a cohesive theory and are patches over patches.

Like if you do playout with pass stones, onesided dame is natural consequence. If you don't like that, you have a problem with the very logic behind pass stones - in that case no reason to do playout with them.

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 Post subject: Re: GT territory rule
Post #92 Posted: Fri Aug 27, 2021 12:56 pm 
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jann wrote:
You also seem to overestimate the extent of acceptable complexity of go rules. Even a single hack like pass stones or pass for ko is borderline, bigger and more (like 2-3 complicated inventions at the same time) are too much. And the more you use the more likely those lack a cohesive theory and are patches over patches.

Like if you do playout with pass stones, onesided dame is natural consequence. If you don't like that, you have a problem with the very logic behind pass stones - in that case no reason to do playout with them.


I agree with you Jann and I am not satisfied by having both 3) and 4) points.
But here is a good news. When analysing points 3) and 4) it appears to me that if 3) is fullfilled then, 4) should (must?) be fullfilled.

=> now I propose simply:

A set of locations is a "controlled area" for a player if:
1) The inside border contains neither empty locations nor stones of the opponent.
2) The outside border contains neither empty locations nor stones of the player.
3) the set of locations can be entirely covered by a "two-eye formation" through an hypthetical play (see below) played only on the "controlled area", assuming the outside border independantly alive


That way, provided it works, not only it is not a complication, but it is a major simplification : instead of playing the hypothetical play on all the board you play it only on the potential "controlled area" which looks far more simple and simplier than many other hypothetical plays I know.

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 Post subject: Re: GT territory rule
Post #93 Posted: Fri Aug 27, 2021 1:10 pm 
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Gérard TAILLE wrote:
Let's try with this wording:

A set of locations is a "controlled area" for a player if:
1) The inside border contains neither empty locations nor stones of the opponent.
2) The outside border contains neither empty locations nor stones of the player.
3) the set of locations can be entirely covered by a "two-eye formation" even if the opponent plays first in an alternation game using normal play and the "permanently prohibited" ko (see here after)

A "player's territory" is all the locations which are empty or occupied by an opponent stone, in a "player's controlled area".


Perfect. Now it makes sense :tmbup:

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 Post subject: Re: GT territory rule
Post #94 Posted: Fri Aug 27, 2021 1:16 pm 
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Pio2001 wrote:
Gérard TAILLE wrote:
Let's try with this wording:

A set of locations is a "controlled area" for a player if:
1) The inside border contains neither empty locations nor stones of the opponent.
2) The outside border contains neither empty locations nor stones of the player.
3) the set of locations can be entirely covered by a "two-eye formation" even if the opponent plays first in an alternation game using normal play and the "permanently prohibited" ko (see here after)

A "player's territory" is all the locations which are empty or occupied by an opponent stone, in a "player's controlled area".


Perfect. Now it makes sense :tmbup:


Thank you Guillaume. OC I understand your comment concerns my defintion of "territory" because I just changed the point 3)


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Post #95 Posted: Fri Aug 27, 2021 1:51 pm 
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Gérard TAILLE wrote:
For the time being two positions are an issue for my "GT territory rule".

Firstly the following position I analysed in https://lifein19x19.com/viewtopic.php?p=266754#p266754

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

I concluded in "GT territory rule" that black has a territory in the upper right corner though a seki seems more appropriate.

And secondly the position found by Jann and showed in https://lifein19x19.com/viewtopic.php?p=266868#p266868

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

Here "GT territory rule" concludes to territory though a seki seems more appropriate.

Two positions is already too many isn't?
That means that I missed something.

Maybe you missed "There is no territory in seki"? :D

Joking aside. To give you a suggestion before I reveal the solution to you (which might be different from the following that would work too):

Click Here To Show Diagram Code
[go]$$B
$$ +---------------+
$$ | O O . X . O O |
$$ | O O . X . O O |
$$ | X X X X X X X |
$$ | ? ? ? ? ? ? ? |[/go]

Black claims territory at the top.

Click Here To Show Diagram Code
[go]$$B
$$ +---------------+
$$ | P P C X C P P |
$$ | P P C X C P P |
$$ | X X X X X X X |
$$ | ? ? ? ? ? ? ? |[/go]

8 x :wx: + 4 x :ec: = 8 x 2 + 4 x 1 = 16 + 4 = 20

-------------

Click Here To Show Diagram Code
[go]$$B
$$ +---------------+
$$ | O O 3 X 7 O O |
$$ | O O 1 X 5 O O |
$$ | X X X X X X X |
$$ | ? ? ? ? ? ? ? |
$$ | ? ? ? ? ? ? ? |
$$ | 2 4 6 8 . . . |[/go]


Click Here To Show Diagram Code
[go]$$B
$$ +---------------+
$$ | C C X X X C C |
$$ | C C X X X C C |
$$ | X X X X X X X |
$$ | ? ? ? ? ? ? ? |
$$ | ? ? ? ? ? ? ? |
$$ | @ @ @ @ . . . |
$$ | Q Q . . . Q Q |
$$ | Q Q . . . Q Q |[/go]

8 x :ec: + 4 x :wt: + 8 x :ws: = 8 x 1 + 4 x 1 + 8 x 1 = 8 + 4 + 8 = 20

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 Post subject: Re: GT territory rule
Post #96 Posted: Fri Aug 27, 2021 1:52 pm 
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Gérard TAILLE wrote:
instead of playing the hypothetical play on all the board you play it only on the potential "controlled area"

This basically reverts to LJRG by Pauli. I think LJRG is not bad, but it still has some theoretical weakness (hidden redundancy).

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Post #97 Posted: Fri Aug 27, 2021 2:36 pm 
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jann wrote:
Gérard TAILLE wrote:
instead of playing the hypothetical play on all the board you play it only on the potential "controlled area"

This basically reverts to LJRG by Pauli. I think LJRG is not bad, but it still has some theoretical weakness (hidden redundancy).

For sure some defintions are identical but the rules seem really different unless I do not have the right link OC. It seems that in this rule there are no confirmation phase and the normal play is different due to the handling of loops. It seems not that close to japanese traditional rule and I see easily positions which are handled differently in LJRG and in japanese traditional rule.
Surely time is needed to analyse my proposition but for the time being I can only wait for issues that could be discovered with specific positions.
Did you find already one Jann?

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 Post subject: Re: GT territory rule
Post #98 Posted: Sat Aug 28, 2021 3:01 am 
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Sure, he also has a messy cycle rule hack (that is best forgotten), but the essence of his rules is the same (see #14 in his short text). LKRG might be a more correct name though (see also #2 from this post). OC, you also want to mess with combined moonshine...

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 Post subject: Re: GT territory rule
Post #99 Posted: Sat Aug 28, 2021 3:14 pm 
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Here is my last updated version of my proposal.
BTW what is defined here is not the complete rule itself but only the confirmation phase, simply because I do not claim any change for normal play (in particular concerning loops I assume basic ko and NO RESULT game).
Similarly counted is not adressed here. As usual the score of a player is the sum
1) the prisonners in normal play
2) the number of the empty location in her territories
3) twice the number of opponent stones in her territories

Confirmation phase:

Preliminary definitions:

A "two-eye-formation" is a set of one or several groups of stones of the same player and exactly two empty intersections so that:
1) each of the groups of stones is adjacent to each of the two empty intersections,
2) each of the two empty intersections is adjacent only to the groups of stones.

The "inside border" of an area is all the locations in the area which are adjacent to a location not in the area

The "outside border" of an area is all the locations not in the area which are adjacent to a location in the area

A group of stones of a player is "pass-alive" if it keeps its alive status even if the player continues to pass whenever the opponent makes plays.

An area is "controlled" by a player if:
1) The inside border of this area contains neither empty locations nor stones of the opponent.
2) The outside border ot this area contains neither empty locations nor stones of the player.
3) the area can be entirely covered by a "two-eye formation" through an hypthetical play (see below) assuming the outside border being pass-alive

A "player's territory" is all the locations which are empty or occupied by an opponent stone, in a player's controlled area".


Confirmation phase procedure:
1) One player claims she "controls" a given area. This player is called the "attacker" and the other player is called the "defender".
2) If this area cannot be "controlled" because inside or outside border do not fulfilled the correponding conditions (see above) then the confirmation phase procedure return to 1) for another claim
3) Hypthetical plays take place : the objective of the attacker is to build a "two-eye formation" covering all the potential "controlled" area. The defender's obective is the opposite
4) If the attacker succeeds the territory associated to the "controlled" area is declared the "territory" of the attacker
5) confirmation phase procedure return to 1) for another claim

Definition:
A position is said to be "critical" if this position is reached by a defender's ko capture followed by an attacker's pass

Hypothetical play:
At the beginning of an hypothetical play there are no ko ban
The hypothetical play begins always by a defender move (a play or a pass) and then each player makes moves alternatively.
Normal play is used during hypothetical play except that all the "permanently prohibited kos" created (see below) have to be taken into account (the defender is not allowed to capture a ko which have been "permanently prohibited"
Three successive passes ends always an hypothetical play

Procedure to create "permanently prohibited ko":
As soon as a "critical position" is reached the attacker may (it is not mandatory) claim for creating a "permanently prohibited ko":
1) The attacker proves that she can either reach her objective or reach "critical positions" an infinite number of times
2) The attacker proves that the defender cannot make an infinite number of passes
3) If the defender agrees to point 1) and 2) then the game continues up to the following "critical position"
4) As soon as a new critical position is reached a "permanently prohibited ko" is automatically created for the ko capture made by the defender before the last pass
5) Then the game continue taking into account the "permanently prohibited ko" created and the attacker may later create another "permanently prohibited ko" using again the procedure above.


Comment1 : one consequence of point 2) of "two-eye-formation" is that the two empty intersections cannot be adjacent
Comment2 : point2 defining controlled area concerning outside border means that dame has been filled
Comment3 : point 3 defining controlled area : because the outside border is considered pass-alive you do not need to play a move on the board which is not on the potential controlled area. You can always replace this move by a pass (eventually allowing you to retake a local ko)
Comment4 : territory and its inside border are just the natural concept used by the players during all the game => claiming for a given controlled area is only natural
Comment5 : looking for a "two eye formation" corresponds basically to the work already done during game to verify that the player has really some points in a territory (no seki)
Comment6 : an hypothetical play starts always by the defender => if the attacker missed a teire move then the attacker cannot prove she as a territory.
Comment7 : in a "critical" position it is always defender to play
Comment8 on "permanently prohibited ko": it is a key point to handle potential loops. The idea is to recognize that some loops are advantageous to a player (the easiest example is the monshine life). J89 use pass-for-ko and J2003 ko-pass for that purpose but unfortunately side effects can be observed. As soon as an advantgeous loop has been recognise then a "permanently prohibited ko" allows to break the loop at the advantage of the corresponding player
Comment9 : in practice the two eye formation will never really build because the players will agree to the result far before the theoritical end of the hypothetical play.
Comment10 on Procedure to create "permanently prohibited ko": is the two players do not agree on point 1) and 2) even by using an another board for analysis then the referee will decide.

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 Post subject: Re: GT territory rule
Post #100 Posted: Sun Aug 29, 2021 2:21 am 
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Well done :tmbup:

I appreciate expecially the new section with comments at the end.

Just a tiny suggestion with regard to these:
You might want to add something like
"{n}"
to the legal text of your rules as a reference to
"Comment n:"

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