Exercise 17.2.17. (a) Give a counterexample that proves that the binary relation C in Fig- ure 17.2.3 is not transitive. (*Hint*) (b) Explain why the binary relation R = {(1,4), (1, 1), (4,1)} is not transitive. (*Hint*) (c) Explain why the binary relation is transitive. (*Hint*) R= {(1,2), (1,3), (1,4)}

Advanced Engineering Mathematics
10th Edition
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Author:Erwin Kreyszig
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Chapter2: Second-order Linear Odes
Section: Chapter Questions
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Please do Exercise 17.2.17 part A,B, and C and please show step by step and explain

Hint for A: There are actually three counterexamples, you only need to find one.

Hint for B: Give a specific example where a ∼ b and b ∼ c but a (/∼) c. In other words, (a, b) and (b, c) are elements of R∼, but (a, c) is not in R∼. It is not necessary for a, b, and c to be distinct. 

Hint for C: Explain why it is impossible to find a counterexample.

Exercise 17.2.17.
(a) Give a counterexample that proves that the binary relation C in Fig-
ure 17.2.3 is not transitive. (*Hint*)
(b) Explain why the binary relation
R = {(1,4), (1, 1), (4,1)}
is not transitive. (*Hint*)
(c) Explain why the binary relation
is transitive. (*Hint*)
R = {(1,2), (1,3), (1,4)}
Transcribed Image Text:Exercise 17.2.17. (a) Give a counterexample that proves that the binary relation C in Fig- ure 17.2.3 is not transitive. (*Hint*) (b) Explain why the binary relation R = {(1,4), (1, 1), (4,1)} is not transitive. (*Hint*) (c) Explain why the binary relation is transitive. (*Hint*) R = {(1,2), (1,3), (1,4)}
Example 17.2.16. Let's think about binary relations on {1,2,3} as seen
in Figure 17.2.3. Which of the binary relations, A, B, or C, are transitive?
Why or why not?
B
AZA
3
2 3
C
2
Figure 17.2.3. Digraphs to correspond with Example 17.2.16
Is the relation in A transitive? Let's consider Remember how transitivity
is defined: if a ~ band b~ c then a~ c. In more prosaic terms, if there's
an arrow from a to b and another arrow from b to c, then there's an arrow
directly from a to c. We may conceptualize this as follows. Suppose a, b, and
c represent airports, and arrows represent flights between airports. In terms
of this example, transitivity means that whenever there's an indirect route
between airports (with multiple stops), then there's also a direct route. So
in the case of relation A, we may notice there's an indirect route from 3 to
2 by going through 1, but there's also a direct route from 3 to 2 (or more
formally, 3~ 1, 1 ~ 2, and 3~2). Furthermore this is the only example
in A of an indirect route. Therefore this relation is transitive. If 3~ 2 is
removed from this binary relation, then the relation isn't transitive because
it's still be possible to get from 3 to 2 via 1, but there's no longer a direct
route.
2
Transcribed Image Text:Example 17.2.16. Let's think about binary relations on {1,2,3} as seen in Figure 17.2.3. Which of the binary relations, A, B, or C, are transitive? Why or why not? B AZA 3 2 3 C 2 Figure 17.2.3. Digraphs to correspond with Example 17.2.16 Is the relation in A transitive? Let's consider Remember how transitivity is defined: if a ~ band b~ c then a~ c. In more prosaic terms, if there's an arrow from a to b and another arrow from b to c, then there's an arrow directly from a to c. We may conceptualize this as follows. Suppose a, b, and c represent airports, and arrows represent flights between airports. In terms of this example, transitivity means that whenever there's an indirect route between airports (with multiple stops), then there's also a direct route. So in the case of relation A, we may notice there's an indirect route from 3 to 2 by going through 1, but there's also a direct route from 3 to 2 (or more formally, 3~ 1, 1 ~ 2, and 3~2). Furthermore this is the only example in A of an indirect route. Therefore this relation is transitive. If 3~ 2 is removed from this binary relation, then the relation isn't transitive because it's still be possible to get from 3 to 2 via 1, but there's no longer a direct route. 2
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