f : A---> A
∣A∣ = n
The first element of the domain has n choices for mapping,2nd element has (n-1) ,3rd element has (n-2) choices and so on.
So, total number of one-to-one functions = n ⨉(n-1)⨉(n-2)⨉(n-3).........⨉1 = n!
23642 Points
17188 Points
8734 Points
6404 Points
5478 Points
5098 Points
4882 Points
4478 Points
4008 Points
3960 Points
Gatecse
X->YZ , Y->XZ , ...