- Each and every element of the domain should have an image in the co-domain,
but all the elements in the co-domain need not have pre-images.
- An element in the co-domain may have more than one pre-image.
The idea may be taught orally with the assistance of a tactile diagram.
A multipurpose magnetic board with oval shapes, pointers and embossed
braille numbers will be useful to teach various concepts in set algebra.
As movement of shapes and arrows are possible on magnetic board, such a
device may be useful for teaching purposes.
- One-to-one function
The function f : A→B is said to be one-to-one if different elements in A have different
images.
In other words, one-to-one function means that to every element of the domain
A, there exists a unique image in the co-domain B.
Eg. :
f : A→B and f(x) = x^2
- Many to one function
The mapping f : A→B is called many to one, if two or more elements of set
A, correspond to one element of set B.
In other words, when two or more elements of the domain A, correspond to the same
element of the co-domain B, that is an element of set A, then it is called as many-to-
one function.
1
2
3
1
4
9
>
>
>
A B
