Page 7 - Discrete Structure II

Exercise II

Let A = {2, 3, 5} B ={ a, b, c}
Which one these is a binary relation from set A to set B
1. (5, 5) ∉ A x B
2. (a, 2) ∉ B x A
3. {(2, a), (5, c) ⊆ A x B
4. {(2, a)} ∈ A x B
5. {(3, c)} ⊆ A x B

Solution

1. (5, 5) ∉ A x B true
2. (a, 2) ∉ B x A false
3. {(2, a), (5, c)} ⊆ A x B true
4. {(2, a)} ∈ A x B false because {(2, a)} is a subset of A x B
5. {(3, c)} ⊆ A x B True