Spight Rules / Discussion

Discuss Spight rules:

 A board play may not repeat a previous whole board position
 unless a pass has intervened since its last occurrence.

 Play stops when the same player passes a second time in the
 same board position.

Wilton Kee:

Does it mean that a pass of one player can erase the board position history of all players?

Bill: A pass, just like a board play, removes ko bans. :-) It cleans the slate and starts fresh from the current position. (OC, for ending the game all positions where a player has passed must be remembered.)

I think of one bestiary in the 1x8 go board:

An interesting White 2  

A perfect play of should be at a. After that is placed on current . This yields Black winning 3 points. Then what is the consequence of this ?

Bill: As you know, Wilton, small boards are very sensitive to the rules. With my rules it is not at all clear that is wrong by area scoring (or territory scoring, for that matter). E. g.,

Canonical play?  

End result: +2.

Wilton Kee:

Best Black 3 should be:  

Now White has two choices:

Choice 1 of White 4  

Continued...  

pass.

Continued...  

Continued...  

Black 11 is in the diagram. End result: +3

Choice 2 of White 4  

Continued...  

and are passes.

Continued...  

Black 11 is in the diagram. End result is also +3.

Bill: Thanks, Wilton. That looks right. :-)

Naughty Black 3  

Let's say leans on .

Sandwiching  

Capture  

If captures another side, you can jump to several graphs later by yourself.Variation 1

Another sandwiches  

If captures another side, you can jump to 3 graphs later by yourself.

Another captures  

Capture race continues  

Jump to here  

Well, b is the best move for . However, if passes:

If White 4 passes  

Passing White 6 is a must.

This is where the bestiary occurs - now White 8 has nothing to do but to pass. But it helps Black to get rid of her history.

White 8 passes  

Black makes use of White's pass  

Forced moves to White  

Returning to all black  

Bill: is banned. It repeats the position resulting from (pass). No pass has intervened since then.

(Passes are treated like board plays as regards ko bans. The same would be true if had been a board play. The superko rule is positional.)

Nothing can be done for White. She passes again.

That's the end of the game. Black wins all 8 points. I just wonder why White's continuing struggle doesn't count (despite the imperfect moves in the past). I don't think Black really has the right to gain all points.

Bill: As it turns out, he doesn't. :-)

However, my rules do not guarantee no anomalous results if a player makes a mistake; in particular, if a player passes in a hot position. The end of play rules are meant to apply when the play is really over, not before.

That having been said, I agree that White's earlier mistakes are irrelevant here.

Diagram 1  

We could start from this position with Black to play. :-)

Anomaly is in the eye of the beholder, but Spight rules are immune to this kind of anomaly, where the game ends in a hot position (Diagram 2) and no one has erred.

Diagram 2  

(The only known exception occurs with molasses ko, and arguably that's a good thing. ;-))

Wilton Kee:

I fail to replicate the canonical moves from diagram 1 so that it ends at diagram 2. Could you please kindly elaborate?

Bill: That's what I'm saying. There is none. :-)

Variation 1

Bill:

White takes the 1-7  

Sacrifice  

White regains the right end.  

The end result with area scoring will be +1.