(*#* **Non-example of a group: $\langle$#⟨#[nat],[[+]]$\rangle$#⟩#
There is no inverse function for the natural numbers with addition.
*)
(*#* **Non-example of a group: $\langle$#⟨#[nat],[[+]]$\rangle$#⟩#
There is no inverse function for the natural numbers with addition.
*)