Say we have a setup with $A$ an integrally closed domain over its fraction field $K$, $L/K$ a separable extension of degree $n$, $B$ the integral closure of $A$ in $L$, $\{e_1, ..., e_n \}$ a basis for $L/K$ contained in $B$, and $\overline{K}$ a fixed algebraic closure of $K$. Also we have $n$ distinct embeddings of $L$ into $\overline{K}$, just like we said above. We call them $\sigma_i$
For $\alpha \in L$, we write down $\alpha$ in terms of the basis elements times some elements of $K$, namely $x_1 e_1 + ... + x_n e_n$. Now some questions