Martian problem

jaeup · **#81**

Bill Spight wrote:

Nice position.

Here is an SGF. I started with no passes as the default and worked from there.

Edit: Silly me. :lol:

I only checked the edited version, so I cannot see what was your initial mistake. Anyway, freezing the game is the best strategy for both, but this is a true disaster for the Japanese rulemakers. They never wanted the game to end this way, and expected the hypothetical play to prevent it.

Here is one minor objection: after two passes, is D7 a dead stone? In the hypothetical play, Black will play at F5 and claim that it is a newly created stone. Anyway, it doesn't really matter because all stones will stay on the board regardless of the fate of D7.

jaeup · **#82**

Gérard TAILLE wrote:

In that case, in one hand you can say the black group is dead under normal God's play and in the other hand you can say the black group is alive under hypothetical God's play.

Yes, it is a true nightmare. The rule asks White to capture the Black stones because "Black can make a life (in the hypothetical play)", but after White's capture, Black cannot make a life (in the real play). Still, because of the one stone addition, White loses the game.

Matti · **#83**

Gérard TAILLE wrote:

Matti wrote:

Yes Matti, of course I realize that I did not mentionned this point, sorry for that.

Anyway, taking your point into account, I looked for this version of the martian problem and I concluded that this new problem is far easier that the original one, though it is quite interesting. Instead of just excluding a move due to a simple ko you can also chose to exclude a move due to a superko.
With this in mind I built the following solution:

White to play

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

starting from this position white captures all black stones and continue until position:

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

here black captures all white stones and now you can build the following very simple martian position

Black to play

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

japonese rule : black must pass to avoid giving an additional prisoner
AGA rule : black must play "a" to save its stones and reach soon a seki
chinese rule : black must play "b" to reach an immediat seki because white cannot answer "a" due to superko

Note : for the original martian problem I searched for a solution with a molasses ko but I had to give up. The two solutions I found do not use this molasses ko scheme.

I see. If one has superko restrictions to start with, they may be at arbitrary locations. PSK and SSK might have different restrictions. This could be achieved by capturing all white and/or black stones from the board multiple times. However a single ko is a different thing. If one wants to use molasses ko, a single ko restriction is necessary.

Bill Spight · **#84**

jaeup wrote:

Bill Spight wrote:

Nice position.

Here is an SGF. I started with no passes as the default and worked from there.

Edit: Silly me. :lol:

I only checked the edited version, so I cannot see what was your initial mistake. Anyway, freezing the game is the best strategy for both, but this is a true disaster for the Japanese rulemakers. They never wanted the game to end this way, and expected the hypothetical play to prevent it.

Who knows what went through the minds of those who came up with the anti-seki?

Quote:

Here is one minor objection: after two passes, is D7 a dead stone? In the hypothetical play, Black will play at F5 and claim that it is a newly created stone. Anyway, it doesn't really matter because all stones will stay on the board regardless of the fate of D7.

Well, the enabling clause is ambiguous in English. However, since Black could play a living stone at F5 anyway, you can argue that White did not enable that stone to be played by taking the ko. The few times that I have seen 生じうる in ancient Japanese go texts in an online collection seem to me to be consistent with that interpretation.

So yes, I think that the D7 stone is dead under hypothetical play. And, as you say, the stone is not removed.

Under Berlekamp's rules (no pass go with prisoner return) Black wins by 0.5, also under Button Go with 0 komi where taking the button lifts ko and superko bans. :w2:

takes the button in the mainline, which lifts the ko ban, but costs 0.5 point.

Gérard TAILLE · **#85**

Matti wrote:

Gérard TAILLE wrote:

Matti wrote:

Yes Matti, of course I realize that I did not mentionned this point, sorry for that.

Anyway, taking your point into account, I looked for this version of the martian problem and I concluded that this new problem is far easier that the original one, though it is quite interesting. Instead of just excluding a move due to a simple ko you can also chose to exclude a move due to a superko.
With this in mind I built the following solution:

White to play

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

starting from this position white captures all black stones and continue until position:

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

here black captures all white stones and now you can build the following very simple martian position

Black to play

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

japonese rule : black must pass to avoid giving an additional prisoner
AGA rule : black must play "a" to save its stones and reach soon a seki
chinese rule : black must play "b" to reach an immediat seki because white cannot answer "a" due to superko

Note : for the original martian problem I searched for a solution with a molasses ko but I had to give up. The two solutions I found do not use this molasses ko scheme.

I see. If one has superko restrictions to start with, they may be at arbitrary locations. PSK and SSK might have different restrictions. This could be achieved by capturing all white and/or black stones from the board multiple times. However a single ko is a different thing. If one wants to use molasses ko, a single ko restriction is necessary.

Yes Matti I see also what you mean.
Though my original intention was to look for a position starting a game, I confess I will be very interesting if you find a position (maybe simplier than mine!) which uses only a simple ko to reach this starting position. Sure I will happy to analyse such finding!
Good search!

Matti · **#86**

I have now found a position where all three rule stes have distinct best starting moves, but they are able to prolong the game without gaining points by choosing other moves.

Gérard TAILLE · **#87**

jaeup wrote:

Gérard TAILLE wrote:

In that case, in one hand you can say the black group is dead under normal God's play and in the other hand you can say the black group is alive under hypothetical God's play.

Yes, it is a true nightmare. The rule asks White to capture the Black stones because "Black can make a life (in the hypothetical play)", but after White's capture, Black cannot make a life (in the real play). Still, because of the one stone addition, White loses the game.

I see why you are you talking about a white stone addition but keep in mind that after the hypothetical phase, stating the black stones are alive, white claim logically for the resumption of the game but now, God tells white that the best move is not to capture the black stones but to pass!!

Gérard TAILLE · **#88**

Matti wrote:

I have now found a position where all three rule stes have distinct best starting moves, but they are able to prolong the game without gaining points by choosing other moves.

I perfectly understand this point because it was also for me a great difficulty to avoid these "non natural" moves giving exactly the same result than the "normal" best move.

Anyway I see you have made great progress doesn't you?

Matti · **#89**

Gérard TAILLE wrote:

Matti wrote:

I have now found a position where all three rule stes have distinct best starting moves, but they are able to prolong the game without gaining points by choosing other moves.

I perfectly understand this point because it was also for me a great difficulty to avoid these "non natural" moves giving exactly the same result than the "normal" best move.

Anyway I see you have made great progress doesn't you?

Yes.

I think now I have a solution on 10*10 board.

Gérard TAILLE · **#90**

Matti wrote:

Gérard TAILLE wrote:

Matti wrote:

I have now found a position where all three rule stes have distinct best starting moves, but they are able to prolong the game without gaining points by choosing other moves.

I perfectly understand this point because it was also for me a great difficulty to avoid these "non natural" moves giving exactly the same result than the "normal" best move.

Anyway I see you have made great progress doesn't you?

Yes.

I think now I have a solution on 10*10 board.

Fantastic Matti.
I will be very happy to analyse it and appreciate your job!
If you prefer to let the other players search without knowing a solution, maybe we can exchange via private messages. It is up to you to decide.

Matti · **#91**

Gérard TAILLE wrote:

Matti wrote:

I think now I have a solution on 10*10 board.

Fantastic Matti.
I will be very happy to analyse it and appreciate your job!
If you prefer to let the other players search without knowing a solution, maybe we can exchange via private messages. It is up to you to decide.

If I send you my soluton, maybe you can send yours in exchange.

Gérard TAILLE · **#92**

Matti wrote:

Gérard TAILLE wrote:

Matti wrote:

I think now I have a solution on 10*10 board.

Fantastic Matti.
I will be very happy to analyse it and appreciate your job!
If you prefer to let the other players search without knowing a solution, maybe we can exchange via private messages. It is up to you to decide.

If I send you my soluton, maybe you can send yours in exchange.

Of course yes.
What can I gain by keeping my work only for myself without anyone verfying my work and without anyone appreciating such work!
My view was only to let you the pleasure of resolving the problem by yourself.
After almost one month, unless somebody tells us she is still searching, I will give my solutions on this forum.

Gérard TAILLE · **#93**

Matti,
BTW a searched solutions only on goban of odd dimension (typically 9, 11 or 13).
Reviewing my solution one of them seems to fit easily in a 10x10 goban. I will just take some more time to verify in detail.

Gérard TAILLE · **#94**

White to play

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

Here is a position I quite like, witch detects if the martian plays under chinese PSK rule.
In other words the best move a chinese PSK player must play, is a bad move for a japonese player or an AGA SSK player (at least I hope so !)

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!

Matti · **#95**

I first sent this solution as personal message to Gérard TAILLE. I sent it here for further discussion.

Matti · **#96**

Matti wrote:

I first sent this solution as personal message to Gérard TAILLE. I sent it here for further discussion.

I discovered a flaw in the position, Here is the corrected one:

Gérard TAILLE · **#97**

Matti wrote:

Interesting position but I have difficulties to catch the point
With japonese rules, because black looks like the komonster, it seems to me thet the stupid :b1:

at "b" is also a best move.

Matti · **#98**

Gérard TAILLE wrote:

Matti wrote:

Interesting position but I have difficulties to catch the point
With japonese rules, because black looks like the komonster, it seems to me thet the stupid :b1:

at "b" is also a best move.

is not best.

Gérard TAILLE · **#99**

Matti wrote:

Gérard TAILLE wrote:

Matti wrote:

Interesting position but I have difficulties to catch the point
With japonese rules, because black looks like the komonster, it seems to me thet the stupid :b1:

at "b" is also a best move.

is not best.

Matti · **#100**

Matti wrote:

Gérard TAILLE wrote:

Interesting position but I have difficulties to catch the point
With japonese rules, because black looks like the komonster, it seems to me thet the stupid :b1:

at "b" is also a best move.

Matti wrote:

is not best.

Gérard TAILLE wrote:

Martian problem

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