 Infinite cardinal arithmetic (source code)

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= Infinite cardinal arithmetic

For infinite cardinals, choice gives $\kappa+\kappa=\kappa\cdot\kappa=\kappa$. Exponentiation satisfies $(\kappa^\lambda)^\mu=\kappa^{\lambda\mu}$, while a countable sum of cardinals has size the maximum of $\aleph_0$ and their supremum.

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