Definition:Subadditive Function


 * Subadditive Function (Conventional Definition): $$f \left({x + y}\right) \le f \left({x}\right) + f \left({y}\right)$$


 * Subadditive Function (Measure Theory): $$f \left({A \cup B}\right) \le f \left({A}\right) + f \left({B}\right)$$
 * In this context, also see Countably Subadditive Function.