Rock, paper, scissors, algebra

Aatish Bhatia posted something interesting on Twitter: if you define multiplication on Rock, Paper, Scissors to be the winner of a match, the result is commutative but not associative.

The same is true of the extension Rock, Paper, Scissors, Lizard, Spock

Rules of rock, paper, scissors, lizard, spock.

Related post: Weakening the requirements of a group

One thought on “Rock, paper, scissors, algebra

  1. It may seems unusual to be commutative but not associative, but
    it’s actually somewhat common. I think it’s a big part of the reason floating point arithmetic can be confusing for many people, e.g.

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