Pie Rule

    Keywords: Variant

The pie rule for Go works as follows:

  • Player A plays Black's first move.
  • Player B decides whether to be Black or White.

This rule provides a way to make the game fairer without the use of komi. Although rarely used in Go, the analogous rule (in a different, but equivalent, form) is normal practice for Hex, and the rule can also be used with many other board games. The name refers to the idea of one person cutting a pie in half, and the other person choosing which half to have.

Player A should obviously aim to choose a move that is not too good (so Black doesn't have an advantage) and not too bad (so White doesn't have an advantage). There are 55 essentially different moves to choose from, and the best is probably about 14 points better than the worst, so it's possible that there is at least one point which makes the game entirely fair, in the sense that it would be a jigo with best play.

It's not clear, however, which point (if any) would do the trick. 2-2 may be a candidate.[1]


Those interested in pie like rules for equalization should look at the opening rules for [ext] Renju, a Gomoku variant. Black chooses the first three moves, then White can change sides. After White 4, played by the new White, Black must pick two moves, and White can select which one stands. After all that, Black still has an advantage, and gets lots of restrictions in the rest of the game.

Bill: That last statement is confusing. Does Black still have an advantage if Black is now White? (The original White switched sides.)

Maybe a different terminology would help. "Player A chooses the first three moves, then Player B chooses whether to play Black or White.... Black still has an advantage."


Another pie-like rule used in [ext] gomoku:

  • Player A places two Black stones and one White stone
  • Player B decides whether
    • to play Black,
    • to play White, OR
    • to place another White stone and another Black stone, and pass the colour choice back to player A[2].

Auction Komi

On the other hand, instead of picking the first move(s), one player could pick komi. Then the other player chooses Black or White. Variants on this have the players bidding for komi.

There should exist a Fair Komi, in the same sense as above: a jigo with best play.

[1] In a RGG [ext] thread from April 2000, Simon Goss suggested the 10-2 point, but others felt this was too good. Bill Taylor suggested 2-2.

fool (2023-04-04): AI Sensei free version sort of agrees, FWIW: with 0 komi opening on 10-2, it puts Black at +3.2, and opening on 2-2, it puts Black at +0.9, and I am unable to find anything it considers closer to 0.

[2] fool (2023-04-04): I assume, it means that player A only has the choice to play Black or White. But... why not let player A the third option also? Play one more White move, and one more Black move, and then, pass the choice back to player B, who would still have the third option...

Pie Rule last edited by fool on April 4, 2023 - 07:27
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