What is the Definition of an Ordered Field?

In summary, the concept of an ordered field has two different definitions. One states that it is a field with a total order, while the other requires it to also satisfy certain conditions regarding addition and multiplication. It would not make sense to simply define an ordered field as a field with an order without specifying these rules. An example of a field with a total ordering but not satisfying the extra conditions is the complex numbers with the dictionary ordering.
  • #1
Buri
273
0
Hi I've looked up the definition of an ordered field and I've found two slightly different ones. One is that an ordered field is a field with a total order, but I've found another which requires it to also satisfy:

(1) If a <= b then a + c <= b + c
(2) If 0 <= a and 0 <= b, then 0 <= ab.

Which one is the correct one? And could someone give me an example of a field which has a total ordering but doesn't satisfy the extra conditions? Thanks I'd appreciate it :)
 
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  • #2
It would make no sense to define an "ordered field" as simply a field with an order. Any time you put together two concepts, such as "order" and "field", you must have some rules for how they work together, which is what your (1) and (2) do.
 
  • #3
I think the complex numbers with the dictionary ordering are an example, but I'm not sure.
 

What is an ordered field definition?

An ordered field definition is a mathematical concept that describes a set of numbers with two properties: a total order relation and the field operations of addition and multiplication. This allows for the comparison and manipulation of numbers in a consistent and logical manner.

What is a total order relation?

A total order relation is a mathematical concept that defines a relationship between two elements of a set. In an ordered field, this relation is used to compare numbers and determine which is greater, less than, or equal to the other.

What are the field operations of addition and multiplication?

The field operations of addition and multiplication are two mathematical operations that are defined in an ordered field. Addition is used to combine two numbers, while multiplication is used to repeatedly add a number to itself a certain number of times. These operations must follow specific rules in an ordered field to maintain consistency and coherence.

What are some examples of ordered fields?

Some examples of ordered fields include the set of real numbers, the set of rational numbers, and the set of complex numbers. These sets of numbers have a total order relation and follow the rules of addition and multiplication, making them suitable for use in mathematical calculations and comparisons.

Why is the concept of an ordered field important?

The concept of an ordered field is important because it provides a foundation for many mathematical concepts and applications. It allows for the comparison and manipulation of numbers in a consistent and logical manner, making it a fundamental concept in fields such as algebra, calculus, and geometry.

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