Upper and Lower bounds?

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The concept of the Upper bounds and lower bound in general used in theory of sets and function .

Let us explain it for you. Consider a set

`S={1/n:n inN }` or

`S={1,1/2,1/3,1/4,.........,1/n,1/(n+1),....}`

The highest elememnt in the set S is 1.

and lowest element 0 which is not in S (because there does not exist a real number when it divide 1 get 0)

But you can understand from here `1/(n+1)>0 AA n`

Thus 0 is lower bound and 1 is an upper bound of set S.

i.e. `0<x<=1 AA x in S`

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