Fuzzy set with discrete non-ordered and ordered universe
Duration: 3 min
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This lecture segment focuses on defining fuzzy sets over discrete universes, specifically contrasting non-ordered and ordered sets. The instructor uses concrete examples to illustrate how membership functions assign values between 0 and 1 to elements in a universe. The first part deals with qualitative, non-ordered data like cities, while the second part addresses quantitative, ordered data like family size.
Chapters
0:00 – 2:00 00:00-02:00
The slide titled "Fuzzy set with a discreet non ordered universe" is presented. The instructor defines a universe X containing cities: {Delhi, Bangalore, Kolkata}. She constructs a fuzzy set C labeled "desirable city to live in," assigning specific membership grades: Delhi gets 0.5, Bangalore gets 0.9, and Kolkata gets 0.6. She underlines the title and highlights the set definitions to emphasize that the objects in the universe are non-ordered. She explicitly states that these membership values are subjective and can vary based on individual preference, noting that one could come up with three different values to reflect their presence. The text on screen confirms the universe contains non-ordered objects.
2:00 – 3:00 02:00-03:00
The lecture transitions to a new slide titled "Fuzzy set with a discreet ordered universe." Here, the universe X is defined as the set of integers {0, 1, 2, 3, 4, 5, 6}, representing the number of children a family might have. The fuzzy set A is described as "Sensible number of children in family." The membership function is explicitly listed as A = {(0, 0.1), (1, 0.3), (2, 0.7), (3, 1), (4, 0.7), (5, 0.3), (6, 0.1)}. The instructor highlights the set description and underlines the mathematical representation. She points out that unlike the previous example, this universe is ordered, yet the membership values remain subjective interpretations of what is "sensible." The slide text reiterates that the universe is discreet and ordered.
The lesson effectively demonstrates the flexibility of fuzzy set theory by applying it to two distinct types of discrete universes. By comparing the non-ordered city example with the ordered family size example, the instructor clarifies that the ordering of elements in the universe does not change the fundamental definition of a fuzzy set, which relies on assigning membership grades. The consistent emphasis on the subjective nature of these values reinforces that fuzzy logic models human perception rather than objective physical laws.