> The [Lambek–Moser theorem](https://en.wikipedia.org/wiki/Lambek–Moser_theorem) is very much a theorem about left and right adjoints applied to the natural numbers (\\(\mathbb{N}\\)), though in the literature, it seems no one has noticed this.
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> What's neat is that the adjoints partition the natural numbers.

This is amazing Keith!

Thank you for pointing this out.