Geoffree
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9. Let S be a set of students, R a set of college rooms, P a set of professors, and C a
set of courses. Let L ⊆ S × R be the relation containing (s, r ) if student s lives in
room r . Let E ⊆ S × C be the relation containing (s, c) if student s is enrolled for
course c. Let T ⊆ C × P be the relation containing (c, p) if course c is lectured by
professor p. Describe the following relations.
a) E −1
(b) L−1;E
(c) E;E −1
(d) (L−1;E); T
(e) L−1; (E; T)
(f) (L−1; L)+
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mqb2766
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(Original post by Geoffree)
9. Let S be a set of students, R a set of college rooms, P a set of professors, and C a
set of courses. Let L ⊆ S × R be the relation containing (s, r ) if student s lives in
room r . Let E ⊆ S × C be the relation containing (s, c) if student s is enrolled for
course c. Let T ⊆ C × P be the relation containing (c, p) if course c is lectured by
professor p. Describe the following relations.
a) E −1
(b) L−1;E
(c) E;E −1
(d) (L−1;E); T
(e) L−1; (E; T)
(f) (L−1; L)+
You must have covered inverse relations
https://www.cl.cam.ac.uk/teaching/10.../exercises.pdf
So what are you stuck with?
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Geoffree
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(Original post by mqb2766)
You must have covered inverse relations
https://www.cl.cam.ac.uk/teaching/10.../exercises.pdf
So what are you stuck with?
how to describe the cyclic relations part (f).
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mqb2766
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(Original post by Geoffree)
how to describe the cyclic relations part (f).
Can you offer a bit more? The inverse part, the composition, ...?
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