In mathematics, a De Morgan algebra is a structure A = such that: is a bounded distributive lattice, and ¬ is a De Morgan involution: ¬ = ¬x ∨ ¬y and ¬¬x = x. In a De Morgan algebra, the laws ¬x ∨ x = 1, and ¬x ∧ x = 0 do not always hold. Wikipedia