## Ordered fields

Abbreviation: OFld

### Definition

An ordered field is a structure $\mathbf{F}=\langle F,+,-,0,\cdot,1,\le\rangle$ such that

$\langle F,+,-,0,\cdot,1\rangle$ is a field

$\langle F,\le\rangle$ is a linear order

$+$ is order-preserving: $x\le y\Longrightarrow x+z\le y+z$

$\cdot$ is order-preserving for positive elements: $x\le y\text{ and }0\le z\Longrightarrow xz\le yz$

It is not unusual to give several (equivalent) definitions. Ideally, one of the definitions would give an irredundant axiomatization that does not refer to other classes.

##### Morphisms

Let $\mathbf{A}$ and $\mathbf{B}$ be … . A morphism from $\mathbf{A}$ to $\mathbf{B}$ is a function $h:A\rightarrow B$ that is a homomorphism: $h(x ... y)=h(x) ... h(y)$

### Definition

An is a structure $\mathbf{A}=\langle A,...\rangle$ of type $\langle ...\rangle$ such that

$...$ is …: $axiom$

$...$ is …: $axiom$

Example 1:

### Properties

Feel free to add or delete properties from this list. The list below may contain properties that are not relevant to the class that is being described.

Classtype universal

### Subclasses

[[Complete ordered fields]]

### Superclasses

[[Ordered rings]] reduced type
[[Fields]] reduced type