
5.7 LinguiStiC VariabLeS 137
In the following example, speed is interpreted as a linguistic variable. For
this example, components of (X, Lx, χ, mx) are given as follows:
X• is the name of the linguistic variable, that is, speed.
Lx• is the set of linguistic values that X can take; here, it is the set {fast,
moderate, slow, very slow}.
χ• is the physical domain that defines crisp values. With regard to the lin-
guistic variable speed, χ is the interval [0, 100], with a unit of km/hour.
m• x is a fuzzy function that maps linguistic terms of the variable to the
equivalent crisp values.
The membership function can be defined as shown ...