olemus
hulga \(X\) alamhulga \(A\) täiend on hulkade vahe \(X\backslash A\)
= complement of the subset A in set X consists of all those elements in X that are not contained in A
https://study.com/cimages/multimages/16/Complement_Set_Venn_Diagram.png

ülevaateid
https://en.wikipedia.org/wiki/Complement_(set_theory)
https://en.wikipedia.org/wiki/Duality_(mathematics)#Complement_of_a_subset
https://ncatlab.org/nlab/show/complement
https://www.vedantu.com/maths/complement-of-set