De Morgan's Laws describe how mathematical statements and concepts are related through their opposites. In set theory, De Morgan's Laws relate the intersection and union of sets through complements. In propositional logic, De Morgan's Laws relate conjunctions and disjunctions of propositions through negation.
In propositional logic and Boolean algebra, De Morgan's laws are a pair of transformation rules that are both valid rules of inference. ... The rules allow the expression of conjunctions and disjunctions purely in terms of each other via negation.
