De Morgan's Laws (Set Theory)

Theorem
De Morgan's laws, or the De Morgan formulas, etc. are a collection of results in set theory as follows.

Set Complement
Strictly speaking, these are not the actual laws he devised, but an application of those laws in the context of set theory.

This result is known by some authors, for example, as the duality principle.

Also see

 * De Morgan's Laws as they arise in logic.