LOYOLA COLLEGE (AUTONOMOUS), CHENNAI – 600 034
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M.Sc. DEGREE EXAMINATION – STATISTICS
THIRD SEMESTER – November 2008
ST 3875 – FUZZY THEORY AND APPLICATIONS
Date : 10-11-08 Dept. No. Max. : 100 Marks
Time : 9:00 – 12:00
SECTION – A |
Answer ALL the Questions (10 x 2 = 20 marks)
- Define Archimedean t-conorm.
- Write the axiomatic skeleton of fuzzy t-norm.
- Define Drastic fuzzy union.
- Explain increasing generator.
- Define arithmetic operations on intervals.
- Define membership function and give an example.
- Find the core of the fuzzy set whose membership function is given by f(x) = exp [– (x – 3)2]
- Give an example of a trapezoidal shaped membership function.
- Explain the sigmoid function used for activation.
- Present the motivation for fuzzy clustering.
SECTION -B |
Answer any FIVE Questions (5 x 8 = 40 marks)
- Define & and prove that , .
- Prove that ,.
- Define dual triple and show that given a t-norm i and an involutive fuzzy complement c , the binary operation u on [0,1] defined by for all is a t-co-norm such that is a dual triple.
- Prove that if for every , then . What will happen when .
- Prove that A is a fuzzy subset of B if and only if αA αB α [0,1].
- Prove that (i) = α( ) and (ii) α ()
- Explain the Lagrange interpolation method for constructing membership function from sample data.
- Describe the architecture of a multi-layer feed-forward network.
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SECTION -C |
Answer any TWO Questions (2 x 20 = 40 marks)
- (a) Prove that A is a fuzzy number if and only if there exists a closed interval
such that where
is monotonically increasing continuous from the right such
that and r is monotonically
decreasing continuous from the left such that r.
(b) Write a short note on Linguistic variables. (15+5)
- Let and B
Find the four basic operations for the fuzzy numbers A and B and also find the
corresponding fuzzy numbers.
- (a) Define equilibrium of a fuzzy complement and show that every fuzzy complement has atmost one equilibrium. Also show that a continuous fuzzy complement has a unique equilibrium.
(b) If a fuzzy complement c has an equilibrium ec, then a ≤ c(a) iff a ≤ ec and
a ≥ c(a) iff a ≥ ec. (14 + 6)
- (a) Explain the direct method with multiple experts for constructing membership function.
(b) Let X ={x1, ..,x5} be a universal set and suppose four experts E1, E2, E3, E4
have specified the valuations of the five as elements of two fuzzy sets A and B
as given in the following table:
Membership in A Membership in B
Element | E1 | E2 | E3 | E4 |
x1
x2 x3 x4 x5 |
0
1 1 0 1 |
1
0 0 1 0 |
1
0 1 0 1 |
0
1 1 0 0 |
Element | E1 | E2 | E3 | E4 |
x1
x2 x3 x4 x5 |
1
0 1 0 1 |
1
0 1 0 0 |
1
0 0 1 0 |
0
1 0 1 1 |
For the set A, the four experts are to be given weights c1 = 1/3, c2 = 1/4, c3 = 1/4,
c4 = 1/6 and for set B, the weights are all equal for the four experts. With these
weights find the degrees of membership of the five elements in A and in B.
Also, evaluate the degrees of membership in A ∩ B using the standard
intersection and in A U B using the algebraic sum operators. (8 + 12)