Go Zendo

This is a Zendo-type game, where the koans are go-positions. The goal is to guess the rule which separates the green boards from the red boards. Anyone may submit a new board, which I will then classify as green or red, or guess a rule, which I will confirm as correct or provide a counterexample to. There is no winner, think of it more as solving a puzzle collaboratively (publicly discussing ideas and working together is encouraged).

Valid koans for this first game are legal positions on a 5x5-board, meaning any position where each chain has at least 1 liberty. The rule does not use any go knowledge apart from the basic definitions of chains (solidly connected groups of stones of one color) and liberties. The rule also does not use the orientation of the board, meaning that any green board rotated or mirrored will still be green, and same for red boards.

Some examples of possible rules (none of them correct for this game of course):
“There are more black stones than white stones”
“All chains contain exactly 2 stones”
“The number of white stones is the same as the number of empty intersections”
“All empty intersections are in the same connected area (i. e. if they were stones they would form a single chain)”
“Each chain is adjacent to exactly 1 chain of the other color”
For each rule, the green boards would be those following the rule, and the red boards those not following the rule.

You can submit boards in any format you like, but preferably using this tool: https://rubymineshaft.github.io/

I’ll start you off with 4 boards of each type, and add new boards here as they are submitted:

Green boards

untitled (7)untitled (2)untitled (4)untitled (8)untitled (11)

Red boards

untitled (6)untitled (5)untitled (3)untitled (10)

The first rule was quickly quessed by @KAOSkonfused

Spoiler for first game

The rule was: If all the stones were the same color, they would form a single connected chain.

Jump to the start of subsequent games:
Second game by le_4TC
Third game by Sanonius
Fourth game by martin3141
Fifth game by RubyMineshaft
Sixth game by Vsotvep
Seventh game by martin3141
Eighth game by le_4TC
Ninth game by RubyMineshaft


So if I want to play I just submit a board and you’ll say red or green?

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Yes! Your board is green and has been added to the original post.

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So if I can post my reasoning here too, I noticed that the examples didn’t involve the edge of the board at all, so I wanted to rule that out.

Also all of the stones are adjacent in the examples so I wanted to see that that could possibly be a criteria. (All the red boards have some stone at a kosumi/tigers mouth etc)


Is the rule something like: “All stones on the board need to be attached to the rest orthogonally (diagonally does not count).”?

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I’m going to guess that the rule is that the number of white stones must be less than or equal to the number of black stones.

I think the first red board has 2 white stones and one black stone.

Edit: sorry yes three

It has three black stones.

Yes! Basically, if all stones were the same color, they would form a single chain. Apparently I made the first one way too easy :smiley:


Ah sh**, I forgot that the red boards are wrong lol

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Naaah, I don’t think it was too easy, but you could have posted fewer examples. :slight_smile:


But what I mean is the number of white stones is less there (less than or equal) to the number of black stones no?

I’ll start you off with just one red and one green for the next one!


Second game!

I’ll let someone else come up with the rule after this if they want, but I’ll do another one since the first went a bit too quick. This should be slightly harder.

Follows the rule:

untitleduntitled (4)untitled (5)untitled (6)untitled (9)untitled (11)untitled (13)untitled (15)untitled (19)

Doesn’t follow the rule:

untitled (1)untitled (3)untitled (2)untitled (8)untitled (10)untitled (12)untitled (14)untitled (17)untitled (18)

The rule has been found:


The third game started here.


board1 ?

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I would like to try as well and submit this:


From now on, I’ll just mark with a like that I’ve added the guess to my post.

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I think we should bring in the guessing stones, ie. the guessing penalty.

Why else wouldn’t I just guess again and again and make the Master create the diagrams? And that’s not as fun as submitting diagrams ourselves.



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how many times may we post in a row?