# Category:Naturally Ordered Semigroup

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This category contains results about the naturally ordered semigroup.

Definitions specific to this category can be found in Definitions/Naturally Ordered Semigroup.

The concept of a **naturally ordered semigroup** is intended to capture the behaviour of the natural numbers $\N$, addition $+$ and the ordering $\le$ as they pertain to $\N$.

### Naturally Ordered Semigroup Axioms

A **naturally ordered semigroup** is a (totally) ordered commutative semigroup $\left({S, \circ, \preceq}\right)$ satisfying:

\((NO 1)\) | $:$ | $S$ is well-ordered by $\preceq$ | \(\displaystyle \forall T \subseteq S:\) | \(\displaystyle T = \varnothing \lor \exists m \in T: \forall n \in T: m \preceq n \) | ||||

\((NO 2)\) | $:$ | $\circ$ is cancellable in $S$ | \(\displaystyle \forall m, n, p \in S:\) | \(\displaystyle m \circ p = n \circ p \implies m = n \) | ||||

\(\displaystyle p \circ m = p \circ n \implies m = n \) | ||||||||

\((NO 3)\) | $:$ | Existence of product | \(\displaystyle \forall m, n \in S:\) | \(\displaystyle m \preceq n \implies \exists p \in S: m \circ p = n \) | ||||

\((NO 4)\) | $:$ | $S$ has at least two distinct elements | \(\displaystyle \exists m, n \in S:\) | \(\displaystyle m \ne n \) |

## Pages in category "Naturally Ordered Semigroup"

The following 19 pages are in this category, out of 19 total.