subadditivity

sub- +‎ additivity

subadditivity (countable and uncountable, plural subadditivities)

1. (uncountable) The state of being subadditive.
2. The statement that a function is subadditive.

   An outer measure ${\displaystyle \mu ^{*}}$ satisfies a property called “subadditivity”, viz.: ${\displaystyle \mu ^{*}{\big (}\bigcup _{j=1}^{\infty }A_{j}{\big )}\leq \sum _{j=1}^{\infty }\mu ^{*}(A_{j})}$. If the less-than-or-equal sign were replaced with an equal sign then the property would be “additivity” instead.

• superadditivity

• subadditivity on Wikipedia.Wikipedia