
5.6 typeS oF Fuzzy FunCtionS 135
5.5.4 Equality of Fuzzy Sets
Let A and B be fuzzy sets on a classical set X. A and B are said to be equal,
denoted A = B, if A ⊂ B and B ⊂ A. That is A = B if and only if A(x) =
B(x) for ∀ x ∈ X.
5.6 TYPES OF FUZZY FUNCTIONS
5.6.1 Quasi-Fuzzy Membership Functions
With this type, the membership function follows a quasi-curve. A quasi-
curve is a real line with a normal fuzzy convex and a continuous member-
ship function satisfying the limit conditions, as demonstrated in Figure 5.8.
lim A(x) = 0, lim A(x) = 0,
x ∞ x −∞
Figure 5.8
Quasi-fuzzy mem-
bership function
5.6.2 Triangular ...