Let $A,B$ be sets, on which addition operations $(A,+)$, and $(B,\oplus)$ are defined. Let $B$ be linearly ordered by some order relation "$\le$".
A subadditive function is a function $f\colon A\to B$ such that for all $x,y\in A$ the inequation $f(x+y)\leq f(x)\oplus f(y)$ holds.
Propositions: 1