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Nimgo

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9x9DoNotPassGo

 

No Pass Go
    Keywords: Rules

Go played with rules amended so that neither player can pass, and a player without a legal play loses (suicide, or at least suicide of one stone, being illegal).

Historically this was called nimgo by Bill Spight in the 1970s. (Also called Conway go by some.) With the benefit of hindsight, it is one attempt to adapt go to the ending condition that is fundamental to CGT. But the game isn't close enough to ordinary go for that to be an acceptable translation. You must have captured stones replayed on the board for that (as in so-called Lasker-Maas rules).


See a number of threads on rec.games.go for more detail (e.g. search for 'nimgo').


Jasonred : AH! I have heard of this rule in other board games! Such as... monopoly. I hear in the states they call in "Go to Jail" though. Some call it "Do not collect $200"...

Bill: Others call it, "Do-not-pass go." ;-)

Chris Hayashida: I thought "No Pass Go" was asking you not to surpass Go-sensei. :)


1 x 5 Nimgo

[Diagram]
Nimgo

[Diagram]
Nimgo(ii)

Black cannot take back, by superko.


[Diagram]
Nimgo(iii)

[Diagram]
Nimgo(iv)

[Diagram]
White wins


Can Black win 1x5 Nimgo?

Yes.

[Diagram]
Tengen(?)

Black makes a strategic sacrifice.


[Diagram]
Game 2 (ii)

[Diagram]
Game 2 (iii)

Now White cannot take back, by superko.


[Diagram]
Game 2 (iv)

[Diagram]
Black wins.


Does Black have to sacrifice at move 3?

Yes.

[Diagram]
Game 3 (i)

[Diagram]
White wins.


-- Bill Spight


Jasonred : Hmmm.. so, how much area or territory or prisoners over the course of the game doesn't matter, just make you opponent not have a legal play left?

...

Not very good for 19x19 boards I suppose...

Bill: Research done mostly by the late John Rickard and myself suggests that moves are roughly proportional to territory. So on large boards the strategy should be much the same as regular go, but the endgame would be much longer.

Jasonred : Why? Territory doesn't matter anymore, as you can play in your opponent's territory without a care. all you need to do is get as many separate eyes as possible, making sure that you haveenough that on you have a minimum of two eyes on your opponent's turn. Also, it's going to be really cool endgame, cause decision of kill or do not kill come into play.

[Diagram]
Don't kill!

In this case, for example, don't ask how it reached that point, the correct play is at the circled point, the square there is just asking for havoc.

As far as I can tell, this is just close to the only possible endgame position, the others being one side having 3 eyes to one eye ratio, or a ko, or superko, or somewhat. But this would probably be like the most common.

Having 2 eyes isn't good enough anymore, you need more than your opponent.

all in all, a weird game. I wouldn't mind a game of 9x9 Do Not Pass Go though. Any takers?

RafaelCaetano: Jason, you ask us not to ask how did it reach that point. But still I wonder, how did Black manage to put so many stones on the board, if White cannot pass? It feels a bit strange. :-)



Robert Pauli: I disagree to Lasker-Maas rules having any relevance in equalizing no-pass go with stone scoring (and with what else?). It's not liberating prisoners, it's releasing them!

Bill: I fail to see the relevance of Lasker-Maas rules, too.

To take John Rickard's example (RGG 01.09.1997):

[Diagram]
W's turn, no prisoners

After White sacrifices 3 stones to shrink Black's big eye down to 1 point, she fills one of her 3 eyes. Under unamended no-pass rules, Black is now forced to fill one of his 2 eyes and eventually lose the game - ignoring the fact that he is leading by 3 stones on the board.

Allowing Black to liberate a black prisoner (after a balanced prisoner increase) and to fill his eye with that stone would serve him nothing. What he needs is the allowance to release a white prisoner (dropping it back into the supply) in exchange for not having to add a stone onto the board.

By the way

  • Jean-Claude Chetrit should correct his [ext] page that falsely claims that (unamended) no-pass rules are equivalent to old Chinese rules
  • Yahoo should at least add the prisoner release amendment to stop the exploitation of their rule that after 2 passes in a row and no agreement the one who didn't pass last has to add a stone - which turns the game into Nimgo (RGG 09.03.2003)
Bill: What?!
Robert Pauli: What's the question, Bill?
Bill: I am not familiar with the Yahoo rules, but I think that the rule stated simply introduces pass fights without turning the game into Nimgo.
Robert Pauli: If you feel that passing is best, just do so. However, I'll pass too and disagree to the end, bringing the burden to play back to where it was. Why care to pass at all?
I neither experienced it, and I don't know if passes lift the ko ban there, but it seems effectively to be no-pass go. At the end, one side will have no legal play and run out of time.

No Pass Go Problem 1



This is a copy of the living page "No Pass Go" at Sensei's Library.
(OC) 2004 the Authors, published under the OpenContent License V1.0.