Definition:Superadditive Function (Conventional)

Definition
Let $\struct {S, +_S}$ and $\struct {T, +_T, \preccurlyeq}$ be semigroups such that $\struct {T, +_T, \preccurlyeq}$ is ordered.

Let $f: S \to T$ be a mapping from $S$ to $T$ which satisfies the relation:
 * $\forall a, b \in S: \map f a +_T \map f b \preccurlyeq \map f {a +_S b}$

Then $f$ is defined as being superadditive.

The usual context in which this is encountered is where $S$ and $T$ are both the set of real numbers $\R$ (or a subset of them).