noun
complement; complementary set
Mathematical term for the set of all elements not in a given subset, within a universal set.
集合Aの補集合は、全体集合からAの要素を除いたものです。
The complement of set A is what remains after removing the elements of A from the universal set.
全体集合 is the universal set that defines the context for the complement.
Compound of 補 (supplement, complement) and 集合 (set). A straightforward modern technical term.