is that superadditive is (mathematics|of a function) such that the image of a sum is at least the sum of the images of the summands while subadditive is (of a function) such that the image of a sum is at most the sum of the images of the summands.

## English

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• (mathematics, of a function) Such that the image of a sum is at least the sum of the images of the summands.
• Knot genus is superadditive under band sum because $g\left(K_1\sharp_bK_2\right)\ge g\left(K_1\right)+g\left(K_2\right)$.

#### Antonyms

• The square-root function is subadditive under addition because $\sqrt\left\{a+b\right\}\le\sqrt a+\sqrt b$.