
132 Chapter 5 Fuzzy LogiC
In this definition, X is treated as a universe of discourse, which is a set
with a reference to a context that contains all possible elements of the set. It
is obvious that all of the elements posses the same properties—examples are
all integers, all books in a library, and all vehicles in the world.
Example: Consider a set of temperatures T, which consists of all tem-
perature readings between 0°C to 40°C. That is, if t = 27ºC, t ∈ T. But if it
is claimed, “The temperature is very low,” one cannot be sure that the low
temperature t is a member of T. This example is illustrated in Figure 5.3.
5.4 MEMBERSHIP FUNCTIONS ...