A fuzzy conjunction operator denoted as t(x,y) and fuzzy disjunction operator denoted as s(x,Y) form dual pair if they satisfy the condition:
1
t(x, y) = 1 - s(x, y)
2
t(x, y) = s(1 - x, 1 - y)
3
t(x, y) = 1 - s(1 - x, 1 - y)
4
t(x, y) = s(1 + x, 1 + y)