Martian problem

Gérard TAILLE · Post by **Gérard TAILLE** » Sun Aug 23, 2020 3:12 am

Let me present you a problem I called the "Martian problem":

On a trip to earth a Martian learned to play Go and back on Mars he taught the game to his entire planet and now the Martian champion is at the professional 9th dan level.
You have the opportunity to meet this champion and your goal is to determine what rules (AGA, Chinese or Japanese) he plays. For this you can offer him a position by asking him what (first) move he plays from this position.
Which position do you choose to know its rules of the game (one of three possible) at the sight of this "only" first move? "

In this problem, and concerning ko rule I suppose:
for AGA : strict SSK
for Chinese : strict PSK

For the time being I found two different positions which can fit in a 11x11 goban.

Hoping someone will be interested by such challenge

Gérard

Gérard TAILLE · Post by **Gérard TAILLE** » Thu Aug 27, 2020 7:52 am

Black to move

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

The diagram above, on a 5x5 goban, is not a solution of the martian problem but is a position in which the first move will immediately detect if the rule used is the japonese one, comparing to chinese or AGA rules.

Javaness2 · Post by **Javaness2** » Thu Aug 27, 2020 8:27 am

Should we assume that le man from mars is a liar?

Gérard TAILLE · Post by **Gérard TAILLE** » Thu Aug 27, 2020 9:32 am

Oops, of course not. The man from mars is a very serious player at the 9 dan professionnal level who is unable to play a move other than the best one.
The only problem for you is that you do not know what rule he learned.

Matti · Post by **Matti** » Thu Aug 27, 2020 9:48 am

Gérard TAILLE wrote:Let me present you a problem I called the "Martian problem":

On a trip to earth a Martian learned to play Go and back on Mars he taught the game to his entire planet and now the Martian champion is at the professional 9th dan level.
You have the opportunity to meet this champion and your goal is to determine what rules (AGA, Chinese or Japanese) he plays. For this you can offer him a position by asking him what (first) move he plays from this position.
Which position do you choose to know its rules of the game (one of three possible) at the sight of this "only" first move? "

In this problem, and concerning ko rule I suppose:
for AGA : strict SSK
for Chinese : strict PSK

When the Martian plays his move, what do you expect? Will the move maximize his score? Or do you require that by each rule set there is a distinct winning move, while other moves do not win?

Gérard TAILLE · Post by **Gérard TAILLE** » Thu Aug 27, 2020 10:03 am

Good question.
I only expect he will maximize his score. For that reason I do not need to give a komi for each rule.

phillip1882 · Post by **phillip1882** » Mon Aug 31, 2020 2:26 pm

basek.sgf: (493 Bytes) Downloaded 878 times

i only see a3 as an option for blacks first move no matter the rule set.

Tryss · Post by **Tryss** » Mon Aug 31, 2020 3:32 pm

phillip1882 wrote:
basek.sgf
i only see a3 as an option for blacks first move no matter the rule set.

You missed that this situation is in fact a seki, black will not play A3 but pass instead :

Click Here To Show Diagram Code: [go]$$Bc :b3: pass, :b5: pass, :w6: pass $$ ----------- $$ | O O O . 1 - $$ | X X O O X - $$ | . X O O X - $$ | O X X O O - $$ | 4 2 X X . - $$ -----------[/go]

So the score is W+1 under territory rules (the captured stone at A1 ), better than W+2 in the other lines.

And under area rules, the score is W+2, worse than W+1 in the other lines

Gérard TAILLE · Post by **Gérard TAILLE** » Tue Sep 01, 2020 5:33 am

Correct Tryss.

Seeing you have verify my previous diagram was able to detect the japanese rule I will show you another diagram which intends to detect the AGA rule:

White to move

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

Of course I also discovered a 5x5 position which is able to detect the chinese rule but I would like to let you the pleasure of discovering such position by yourself.

The martian problem itself is of course far more difficult!

Bill Spight · Post by **Bill Spight** » Tue Sep 01, 2020 8:22 am

phillip1882 · Post by **phillip1882** » Tue Sep 01, 2020 9:17 am

Click Here To Show Diagram Code: [go]$$Bc :b3: pass, :b5: pass, :w6: pass $$ ----------- $$ | O O O . 1 - $$ | X X O O X - $$ | . X O O X - $$ | O X X O O - $$ | 4 2 X X . - $$ -----------[/go]

ok but the question is, what would be a different first move territory versus area?

Tryss · Post by **Tryss** » Tue Sep 01, 2020 9:49 am

phillip1882 wrote:ok but the question is, what would be a different first move territory versus area?

With the seki variation Black has 10 points and White 12 points under area scoring, so the score is W+2. But Black will rather play another move, either A3 or E1 :

Click Here To Show Diagram Code: [go]$$Bc $$ ----------- $$ | O O O . 2 - $$ | X X O O X - $$ | 3 X O O X - $$ | O X X O O - $$ | X . X X 1 - $$ -----------[/go]

And then Black has 12 points and White has 13 points : score W+1, better for black than the seki.

So, if the martian play under Area scoring, he'll start with A3 or E1, and if he's playing under Territory scoring, he'll start with E5

phillip1882 · Post by **phillip1882** » Tue Sep 01, 2020 10:19 am

okay thank you for clarifying.

Matti · Post by **Matti** » Sat Sep 12, 2020 1:06 am

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

Black to play. I think, a is best with japanese rules. b is best with AGA rules (SSK) and c is best with Chinese rules (PSK).

Gérard TAILLE · Post by **Gérard TAILLE** » Sat Sep 12, 2020 7:01 am

Matti,

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

takes

connect at

Difficult position with this sutuation in the upper right corner. I guess you spent a lot of time (like I did myself!) to find such position.

In do not understand why, in Chinese rule (PSK), you cannot play "b"?
What about the sequence 1 to 7 in the diagram above, knowing of course that, between each move, you must insert 4 moves in the right corner ?
In addition, even in japonese rules, a move on "b" seems not a bad move (though a little stupid) because black seems able to win the ko "a" in any case.

Life In 19x19

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