Trace of an integral element over a normal domain
= Trace of an integral element over a normal domain
For a <normal domain> $A$ with <fraction field> $K$, the <field trace> of an <integral element> in a finite <separable field extension> $L/K$ belongs to $A$. Its conjugates are integral, so their sum is integral; it lies in $K$ and hence in $A$ by normality. This places the <integral closure> inside a <trace-dual lattice>.