Many-one Function
A function f: A→ B is said to be many-one if two or more than two elements in A have the same image in B.
Example:
Let A = {-1, 1, 2, 3} and B = {1, 4, 9}
Let f: A → B: f(x) = x2 Ɐ x ∈ A
Then, each element in A has a unique image under f in B
f is a function from A to B such that
f(-1) = (-1)2 = 1
f(1) = 12 = 1
f(2) = 22 = 4
f(3) = 32 = 9
Here, two elements namely -1 and 1 have same image 1 ∈ B.
Hence, f is many-one.