Definition:Balanced Set

Definition
Let $\Bbb F$ be a subfield of $\C$.

Let $X$ be a vector space over $\Bbb F$.

Let $A \subseteq X$.

We say that $A$ is balanced :


 * $s A \subseteq A$ for all $s \in \Bbb F$ with $\cmod s \le 1$

where $s A$ is the dilation of $A$ by $s$.