[[Unital magma]]
# Eckmann-Hilton argument

Let $X$ be a set equipped with two binary operations $(\times) : X \times X \to X$ and $(\otimes) : X \times X \to X$ such that these operations are [[Unital magma|unital]] and $(a \times b) \otimes (c \times d) = (a \otimes c) \times(b \otimes d)$ for all $a,b,c,d \in X$.
Then $(\times)=(\otimes)$ and together with $X$ forms a [[Commutative monoid]]. #m/thm/algebra

> [!missing]- Proof
> #missing/proof

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