subadditive set function

subadditive set function

[səb‚ad·əd·iv ′set ‚fəŋk·shən]
(mathematics)
A set function with the property that the union of any finite or countable collection of sets in the range of the function is also in this range, and the value of the function at this union is equal to or less than the sum of its values at each set of the collection.