[Computer-go] implementing simple ko

Robert Jasiek jasiek at snafu.de
Thu Mar 12 06:16:37 PDT 2015

On 12.03.2015 06:07, Ray Tayek wrote:
> i need to implement a simple ko rule.

Supposing you want a strategically simple AND complete ko ruleset, you 
can choose from:

1) short cycle loss (2 or 3 successive plays, see below) + long cycle 
tie ko rule

2) basic ko rule + fixed ko rule (recreating a same position is allowed 
but then a different play must be made)

If you do not search for a complete ko ruleset but for a practically 
easily implemented and feasible:

3) basic ko rule + 3-play-loss (for the player playing to recreate the 

Note that none of these are used by go servers or in the real world. 
However, when experimenting with an early program, such a ko ruleset can 

If you want only a feasible approximation without complexity, you can 
use only the short cycle loss rule (or short cycle is prohibited rule). 
This solves basic ko and sending-2-turning-1 shapes is "good enough" in 
practise until you meet a program designed to trap you into longer cycles.

robert jasiek

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