Does every non-empty set of natural numbers have a unique least element?

66 Views Asked by At

First of all, I apologize if this question is too elementary or pedantic. It is usually said that every non-empty set of natural numbers has a least element. However, books usually don't mention if the least element is unique. So, what is the proof that the least element in a non-empty set of natural numbers is unique?

1

There are 1 best solutions below

3
On BEST ANSWER

Ordering on the natural numbers is anti-symmetric, i.e. if $x\leq y$ and $y\leq x$ then $x=y$