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 Post subject: Re: Martian problem
Post #101 Posted: Sat Sep 19, 2020 1:22 pm 
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Matti wrote:
The prisoners are equal, but :b7: has filled a point of territory, while :w4: has not-

yes :b7: fills a point of territory but it is only an answer to :w6: which gives one prisoner.
For me I see the same number of prisoners in the ko place, and no impact in the rest of the board.

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 Post subject: Re: Martian problem
Post #102 Posted: Sat Sep 19, 2020 2:11 pm 
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Hi Gérard,
Matti is right :

Since eyes in seki don't count, playing a ko threat inside a seki is a clever way to sort out the japanese rule : it's free in chinese or AGA rules (I loose one stone, my opponent looses one point, like with an ordinary ko threat), but it costs one point in japanese rule (I loose one stone, but my opponent's answer is neutral since she plays inside a seki) !

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 Post subject: Re: Martian problem
Post #103 Posted: Sat Sep 19, 2020 2:25 pm 
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Pio2001 wrote:
Hi Gérard,
Matti is right :

Since eyes in seki don't count, playing a ko threat inside a seki is a clever way to sort out the japanese rule : it's free in chinese or AGA rules (I loose one stone, my opponent looses one point, like with an ordinary ko threat), but it costs one point in japanese rule (I loose one stone, but my opponent's answer is neutral since she plays inside a seki) !


Thank you Guillaume, now I see the point!
Move "a" in japonese rule is for me the only correct move
I can now begin to analyse PSK and SSK scenarios

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 Post subject: Re: Martian problem
Post #104 Posted: Sat Sep 19, 2020 3:06 pm 
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Matti,

I am now OK for japonese rule. I really appreciate your idea on this point!

It remains to analyse PSK and SSK rule.

I see the following sequence

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

and now, my feeling is that each palyer has to pass and this variation seems the best one either for SSK and PSK rule.
Can you explain where I am wrong?

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 Post subject: Re: Martian problem
Post #105 Posted: Sat Sep 19, 2020 10:08 pm 
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Gérard TAILLE wrote:
Matti,

I am now OK for japonese rule. I really appreciate your idea on this point!

It remains to analyse PSK and SSK rule.


I answered inside the hidden part.
I see the following sequence

Quote:
Click Here To Show Diagram Code
[go]$$B
$$ -----------------------
$$ | O O 2 3 X O . X X . |
$$ | . O O X X O O O O X |
$$ | O . O X . X X X O . |
$$ | 6 1 O X X . X X O O |
$$ | O O O O O X . X X X |
$$ | X X X X O X X X 5 . |
$$ | X O O X O O X O X X |
$$ | X . . X X X O O O O |
$$ | . O O X O O 4 O . X |
$$ | O . X X X O . O X . |
$$ -----------------------[/go]

and now, my feeling is that each palyer has to pass and this variation seems the best one either for SSK and PSK rule.
Can you explain where I am wrong?


Your sequence is best for PSK. For SSK the best sequence is below.
Click Here To Show Diagram Code
[go]$$B
$$ -----------------------
$$ | O O 1 2 X O . X X . |
$$ | . O O X X O O O O X |
$$ | O . O X . X X X O . |
$$ | . c O X X . X X O O |
$$ | O O O O O X . X X X |
$$ | X X X X O X X X 6 7 |
$$ | X O O X O O X O X X |
$$ | X 9 . X X X O O O O |
$$ | . O O X O O 3 O . X |
$$ | O . X X X O 4 O X . |
$$ -----------------------[/go]

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 Post subject: Re: Martian problem
Post #106 Posted: Sat Sep 19, 2020 11:11 pm 
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It seems that the send two rerurn one corner failed to distinguish PSK and SSK.

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 Post subject: Re: Martian problem
Post #107 Posted: Tue Sep 22, 2020 10:23 pm 
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Gérard TAILLE wrote:

Unless somebody tells me she wish continue to search the original martian problem without knowing a solution, I will give you one of my solutions (on a 11x11 goban) next week, i.e. one month after my first post.

Good search!

Now, one moth has passed.

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 Post subject: Re: Martian problem
Post #108 Posted: Wed Sep 23, 2020 2:03 am 
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As promised, after one month I give you a solution of this martian problem

Black to play
Click Here To Show Diagram Code
[go]$$B
$$ -----------------------
$$ | . a O O . O O . O . |
$$ | X X O X O O X O O O |
$$ | . O O X X X X X X X |
$$ | O O X X . X . X O O |
$$ | X X X X X X X X O O |
$$ | O O O O O O O X X b |
$$ | d X d O O O O X O O |
$$ | O O O O O X O X O . |
$$ | c O X X X X O X O O |
$$ | O X . X . X O X O . |
$$ -----------------------[/go]

Black plays "a" with japanese rule, "b" or "d" with PSK rule and "c" with SSK rule.

Though it was very difficult for me to find such position, when seeing the result, it looks surprisingly rather simple.

In SSK rules the idea is to save black stones in the bottom by the well known send three return two in the bottom left corner.

For distinguishing PSK and japonese rules the idea is simply to use the japonese particularity of counting seki. The point is the following:
with territory counting, a move at "a" gains 4.5 points which is greater than 4 points for a move at "b".
In the other hand, with area counting, a move at "b" gains 5 points which is greater than 4.5 points for a move at "a".

It remains to look at a move at "d" when using japonese or PSK rule. The correct answer to a move at "d" being a white move at "a", you can easily see that a move at "d" is correct under PSK rule but not under japonese rule.

I hope you will appreciate this position!

If your are interested I found a more difficult position using the bent four in the corner

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