Definition:Convex Subset of Natural Numbers

Definition
Let $A \subseteq \N$ be a subset of the set of natural numbers.

$A$ is defined as being convex (in $\N$) :
 * $\forall x, y, z \in \N: \paren {x, z \in A \land x \le y \le z} \implies y \in A$

Also see

 * Definition:Convex Set (Order Theory)