MathGloss

A field EE is a field extension of the field FF if FF is a subfield of EE.

The field extension may be considered as a vector space over FF. The dimension of EE as an FF-vector space is denoted [E:F][E:F], deg(E/F)\deg(E/F), or degF(E)\deg_F(E).

The most basic field extension comes from adjoining an element Θ\Theta to FF. It is denoted F(Θ)F(\Theta), and it is the smallest field containing both FF and Θ\Theta.