Question:
Given A = {2, 3, 4}, B = {2, 5, 6, 7}. Construct an example of each of the following:
(a) an injective mapping from A to B
(b) a mapping from A to B which is not injective
(c) a mapping from B to A.
Solution:
Given, A = {2, 3, 4}, B = {2, 5, 6, 7}
(i) Let f: A → B denote a mapping
f = {(x, y): y = x + 3} or
f = {(2, 5), (3, 6), (4, 7)}, which is an injective mapping.
(ii) Let g: A → B denote a mapping such that g = {(2, 2), (3, 2), (4, 5)}, which is not an injective mapping.
(iii) Let h: B → A denote a mapping such that h = {(2, 2), (5, 3), (6, 4), (7, 4)}, which is one of the mapping from B to A.