11
votes
Accepted
What's the longest possible forced repetition in Go?
Molasses ko: http://denisfeldmann.fr/bestiary3.htm#mol
"The semeai in figure 11 is probably the worst known case of repetition. Known as "molasses ko", ..."
Denis Feldmann's Go Bestiary is a ...
- 236
10
votes
Accepted
Why do asymmetric ko fights exist?
I think the easiest way to think of this is in terms of options, and the freedom to take whatever options benefit me.
In your example, you have no options: You need to win this ko, or you will lose.
...
- 6,682
8
votes
Accepted
Is this a correct formal heuristic for invalid moves due to Ko?
No, this logic unfortunately doesn't work: It prevents moves that are in fact legal, because they include a snapback.
$$ white to play
$$ . . . . . . .
$$ . . X O X . .
$$ . X O X . X .
$$ . X O O O ...
- 587
4
votes
Accepted
Does playing a ko add a dimension to the game?
"Ko" is effectively one of those situations where you can hope to get two moves in a row (e.g. if your opponent spends his next move filling, or otherwise removing the ko).
On the other hand, if your ...
- 21.8k
3
votes
Is this double ko played reasonably by AlphaGo Zero and AlphaGo Lee?
There is a difference between the two semi-stable double ko positions, although a rather small one. C14 reduces the immediate number of liberties of the G13 leg. This means that black will have a free ...
- 533
2
votes
Does playing a ko add a dimension to the game?
I would say the added dimension comes from the "long-range" nature of kos. It is possible, through a ko, for two, otherwise loosely linked regions to be directly compared. Each ko evaluates the entire ...
- 121
2
votes
Accepted
How to apply the ko rule (Go)
The theoretical answer depends whose rules you are using, because different countries use different rules, and have different ways of dealing with the multi-ko1 situation you describe.
In practice ...
- 1,358
2
votes
How to apply the ko rule (Go)
Super Ko can be detected efficiently using Zobrist hashing.
https://en.wikipedia.org/wiki/Zobrist_hashing
https://www.gnu.org/software/gnugo/gnugo_11.html#SEC144
The idea is to pick a random 64-bit ...
- 321
2
votes
Is this a correct formal heuristic for invalid moves due to Ko?
Your rule is adequate to detect simple kos but not all forbidden repetitions. EDIT: It incorrectly forbids snapbacks, as observed in balpha’s answer, and thus fails your condition (2). It is unclear ...
- 1,358
1
vote
Why do asymmetric ko fights exist?
Short answer
How can a ko fight be “asymmetric”? By offering one player a strong incentive to start it.
When a ko is asymmetric
You are right that once the ko is started, the result is equally ...
- 1,358
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