  When $\{\alpha_i\}_{1 \leq i \leq m}$ is a sequence of distinct non-zero
elements of an integral domain $A$ and $\gamma$ is a common multiple of the
$\alpha_i$ in $A$ we obtain, by means of a simple identity for the
  Vandermonde determinant, a lower bound for $\sup_{1\leq i < j \leq
m}\phi(\alpha_i - \alpha_j)$ in terms of $\phi(\gamma)$, where $\phi$ is a
function from the nonzero elements of $A$ to ${\bf R}_{+}$ satisfying certain
natural conditions. We describe several applications of this bound.
