(*#* **Example of a monoid: $\langle$#⟨#[Qpos],$(x,y) \mapsto xy/2$ #(x,y) ↦ xy/2#$\rangle$#⟩#
Two is the unit of the operation $(x,y) \mapsto xy/2$ #(x,y)
↦ xy/2# on the positive rationals. So we have another monoid structure on the positive rational numbers.
*)
(*#* **Example of a monoid: $\langle$#⟨#[Qpos],$(x,y) \mapsto xy/2$ #(x,y) ↦ xy/2#$\rangle$#⟩#
Two is the unit of the operation $(x,y) \mapsto xy/2$ #(x,y)
↦ xy/2# on the positive rationals. So we have another monoid structure on the positive rational numbers.
*)