305 -Fields (4)

February 20, 2009

Suppose that {\mathbb F} is a field and that S\subset{\mathbb F}. It may be that S is also a field, using the same operations of {\mathbb F}. For example, if {\mathbb F}={\mathbb R}, then we could have S={\mathbb Q}.

Definition 15. If {\mathbb F} is a field and S\subset{\mathbb F}, we say that S is a subfield of {\mathbb F} if S is a field with the operations of {\mathbb F}.

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