What's wrong with suicide?

[ChradH]

If we come from a different way, the two choices present themselves like this:

Axiom: There can never be stones without liberties on the board.

No suicide: If a play of one player causes stones of the opposing player to be without liberty, those stones are removed. If a play of one player would cause only own stones to be without liberty, that move is illegal.

Suicide: If a play causes stones to be without liberty, they are removed. Removing opposing stones takes precedence.

How about this?

Axiom: After a play there can never be a stone without a liberty on the board.

No suicide: If placing a stone on a point causes an opposing stone to have no liberty, all such stones are removed.

Suicide: If placing as stone on a point causes a stone to have no liberty, all such opposing stones are removed. After that, all stones without a liberty are removed.

----

I think that rules that allow suicide are more complex than rules that do not.

With respect, your "no suicide" rule is incomplete. It doesn't define what happens to a placed stone ending up with no liberties. And Harlequin's suicide is in fact shorter and less complex than your example.

[Cassandra]

There is a rule which says that stones cannot be on the board if they have no liberties. An obvious consequence of this is that you cannot make a move which results in no liberties. Suicide is logically not possible.

No, the obvious consequence is that if you play a stone which has no liberties, it is removed. Suicide is thus logically possible.

A play is

• placing a stone on an empty intersection, then
• removing all opposing stones that have no liberties, if any, then
• removing all own stones that now still have no liberties, if any.

I agree with DrStraw. Suicide is logically impossible because a group can't have zero liberties. It's that simple.

Your description of what a play is doesn't describe Go the way it is normally played (though it does sound a lot like New Zealand rules).
The way Go is usually played is actually more simple. A play is

• placing a stone on an empty intersection, then
• removing all opposing stones that have no liberties, if any.

"Removing all own stones" is not a step in the traditional game of Go. It is something New Zealand rules introduced for the sake of being cute and simple. It is a clever trick, and I admire its cleverness. But I don't like it. It reminds me of those mathematical proofs where instead of doing three obvious steps you do one step which makes no sense, yet, by magic, everything simplifies and the problem is solved. Such proofs are cute but not helpful.

Let's have a look at the Japanese Rules, which do not mention "suicide" at all.

Article 5 (capture) of the 1989 (edited) ruleset claims that the player, who has taken the last liberty of one or more opponent's stones with his move, must take these opponent's stones off the board. The "move" is completed after the removal. So there is NO coexistence of both colour's stones with no liberties.

Combined with the last sentence of article 4 (stones that may exist on the board) - quoted by DrStraw - it goes without saying that you are not allowed to make a move, which takes the last liberty only of your own stone(s).
By the way: If you ever would, these stone(s) must remain on the board. You are not allowed to take them off the board, because they do not belong to your opponent's stones. And your opponent is not allowed to remove them, because he did not make the last move.

In other words you might say that a player must never do something, which colloquially is called "suicide".

[Bill Spight]

If we come from a different way, the two choices present themselves like this:

Axiom: There can never be stones without liberties on the board.

No suicide: If a play of one player causes stones of the opposing player to be without liberty, those stones are removed. If a play of one player would cause only own stones to be without liberty, that move is illegal.

Suicide: If a play causes stones to be without liberty, they are removed. Removing opposing stones takes precedence.

How about this?

Axiom: After a play there can never be a stone without a liberty on the board.

No suicide: If placing a stone on a point causes an opposing stone to have no liberty, all such stones are removed.

Suicide: If placing as stone on a point causes a stone to have no liberty, all such opposing stones are removed. After that, all stones without a liberty are removed.

----

I think that rules that allow suicide are more complex than rules that do not.

With respect, your "no suicide" rule is incomplete. It doesn't define what happens to a placed stone ending up with no liberties.

Sure it does. The axiom says that placing a stone so that it ends up with no liberty is not a (legal) play.

And Harlequin's suicide is in fact shorter and less complex than your example.

It is also inaccurate. Harleqin's first language is not English, I think.

Suicide: If a play causes stones to be without liberty, they are removed. Removing opposing stones takes precedence.

There is a simple English interpretation that says that if a play causes stones of both players to be without a liberty, all the stones without liberty are removed. (That is within the meaning of the first sentence.) The opponent's stones are removed first. (That accords with one meaning of precedence. )

Edit: Deleted inaccurate statement.

[Harleqin]

I have to admit that I tried to make the text more compact at the cost of precision. Your version is better.

I think that your "no suicide" is lacking explicitness. The fact that the japanese rule text does it in a similar manner indicates to me that actual tradition is not to think at all about suicide.

[HermanHiddema]

If we come from a different way, the two choices present themselves like this:

Axiom: There can never be stones without liberties on the board.

No suicide: If a play of one player causes stones of the opposing player to be without liberty, those stones are removed. If a play of one player would cause only own stones to be without liberty, that move is illegal.

Suicide: If a play causes stones to be without liberty, they are removed. Removing opposing stones takes precedence.

How about this?

Axiom: After a play there can never be a stone without a liberty on the board.

No suicide: If placing a stone on a point causes an opposing stone to have no liberty, all such stones are removed.

Suicide: If placing as stone on a point causes a stone to have no liberty, all such opposing stones are removed. After that, all stones without a liberty are removed.

----

I think that rules that allow suicide are more complex than rules that do not.

In the "Suicide case", the axiom is pointless and can be left out, as it is always true as a result of the rules. In the "No suicide" case, it is required.

I think either case can be written roughly equally elegantly and concisely, and neither option is really more complex than the other.

[Cassandra]

There is no suicide rule or a need for one unless you write a ruleset badly.

... But if you are Chinese or Japanese, the word for move implies rather strongly that you place a stone and leave it there (it "adheres"). ...

The Japanese Kanji used in the books for something like "to play a stone" is 打. It's original meaning is "to hit", "to strike".

It's left part is 手, what means "hand"; it's right part is 丁, what means "nail".

So the Kanji gives an idea of "something to be struck (with the hand)".

[Bill Spight]

There is no suicide rule or a need for one unless you write a ruleset badly.

... But if you are Chinese or Japanese, the word for move implies rather strongly that you place a stone and leave it there (it "adheres"). ...

The Japanese Kanji used in the books for something like "to play a stone" is 打. It's original meaning is "to hit", "to strike".

It's left part is 手, what means "hand"; it's right part is 丁, what means "nail".

So the Kanji gives an idea of "something to be struck (with the hand)".

着手 are the Kanji in the rules. The second one means a play. The first one has a meaning of putting, fixing, or attaching, which seems like the operative one.

[Bill Spight]

I think that your "no suicide" is lacking explicitness. The fact that the japanese rule text does it in a similar manner indicates to me that actual tradition is not to think at all about suicide.

Actually, I was following you.

[Cassandra]

着手 are the Kanji in the rules. The second one means a play. The first one has a meaning of putting, fixing, or attaching, which seems like the operative one.

着 litarally means "arrival" or "clothes". The latter surely has something to do with "attaching". So the meaning may be something like "the hand that attaches" (a stone to the board).

In a Japanese book, where I found the rules in Japanese, 着手 is explained as 石を置く, what means "to put a stone in place".

[HermanHiddema]

If you want it even simpler:

1. Place a stone on the board
2. Remove any opposing stones without liberties.

With these rules, not only is suicide allowed, but the stone(s) placed into suicide will actually remain on the board! Any such stones will then be removed by step 2 of the opponent's next move!

(Yes, this means you can kill some groups that could otherwise not be killed, but the same is true for the current "suicide" vs. "no suicide" rules. It is a valid set of rules )

[Harleqin]

In the "Suicide case", the axiom is pointless and can be left out, as it is always true as a result of the rules. In the "No suicide" case, it is required.

Good point!

I think either case can be written roughly equally elegantly and concisely, and neither option is really more complex than the other.

I agree completely.

[Harleqin]

If you want it even simpler:

1. Place a stone on the board
2. Remove any opposing stones without liberties.

With these rules, not only is suicide allowed, but the stone(s) placed into suicide will actually remain on the board! Any such stones will then be removed by step 2 of the opponent's next move!

In this case, the opponent would be unable to play on those intersections. This would annihilate the liberties axiom.

[HermanHiddema]

If you want it even simpler:

1. Place a stone on the board
2. Remove any opposing stones without liberties.

With these rules, not only is suicide allowed, but the stone(s) placed into suicide will actually remain on the board! Any such stones will then be removed by step 2 of the opponent's next move!

In this case, the opponent would be unable to play on those intersections. This would annihilate the liberties axiom.

Yes, true, it would also mean that this:

$$B
$$ ------------
$$ | 1 X O . . .
$$ | X O O X . .
$$ | O O X . X .
$$ | . X X . . .
$$ | . . . . . .
$$ | . X . . . .
$$ | . . . . . .

Click Here To Show Diagram Code

[go]$$B
$$ ------------
$$ | 1 X O . . .
$$ | X O O X . .
$$ | O O X . X .
$$ | . X X . . .
$$ | . . . . . .
$$ | . X . . . .
$$ | . . . . . .[/go]

is a killing move, rather than a ko threat (when suicide is allowed) or an illegal move (when it isn't).

There is no reason to have the liberties axiom, other than tradition. Going without it just results in yet another variation of Go. A bit further removed from the common ones than most, perhaps, but still a valid rule set.

I really don't think there is any reason to consider rules with suicide superior to those without, it's just a matter of tradition and personal preference. The above example is meant as an illustration of how "simplicity" or "elegance" is not necessarily an argument in favor of certain rules variations. It is, in my opinion, a desirable quality only insofar as it does not intrude upon the basic nature of the game as we know it.

[Harleqin]

The liberties axiom is the most central axiom of Go. Herman's variant goes too far.

[palapiku]

A nice property of suicide not being allowed is that it guarantees that the game will end if one player is rational and the other is just blindly playing everywhere. Eventually he will run out of places to play (superko also does this, but not as quickly). This happened to me on KGS once, I was pissed off.