T(a,b) = ~ S(~a, ~b)
where T = intersection (AND) = T-Norm
and S = union (OR) = T-CoNorm
and ~ = negation (NOT)
The intersection operators in this context are known
as triangular norms, or simply T-Norms, while the
union operators are known as triangular co-norms,
or T-CoNorms.