Partially ordered groups

Abbreviation: PoGrp

Definition

A partially ordered group is a structure $\mathbf{G}=\langle G,\cdot,^{-1},1,\le\rangle$ such that

$\langle G,\cdot,^{-1},1\rangle$ is a group

$\langle G,\le\rangle$ is a partially ordered set

$\cdot$ is orderpreserving: $x\le y\Longrightarrow wxz\le wyz$

Morphisms

Let $\mathbf{A}$ and $\mathbf{B}$ be partially ordered groups. A morphism from $\mathbf{A}$ to $\mathbf{B}$ is a function $h:A\rightarrow B$ that is an orderpreserving homomorphism: $h(x \cdot y)=h(x) \cdot h(y)$, $x\le y\Longrightarrow h(x)\le h(y)$

Examples

Example 1: The integers, the rationals and the reals with the usual order.

Basic results

Any group is a partially ordered group with equality as partial order.

Any finite partially ordered group has only the equality relation as partial order.

Properties

Classtype quasivariety

Finite members

$\begin{array}{lr} f(1)= &1\\ f(2)= &1\\ f(3)= &1\\ f(4)= &2\\ f(5)= &1\\ \end{array}$ $\begin{array}{lr} f(6)= &2\\ f(7)= &1\\ f(8)= &5\\ f(9)= &2\\ f(10)= &2\\ \end{array}$

Subclasses

Lattice-ordered groups expanded type