Smallest Element is Minimal

From ProofWiki
Jump to navigation Jump to search


Let $\struct {S, \preceq}$ be an ordered set which has a smallest element.

Let $m$ be the smallest element of $\struct {S, \preceq}$.

Then $m$ is a minimal element.


By definition of smallest element:

$\forall y \in S: m \preceq y$

Suppose $y \preceq m$.

As $\preceq$ is an ordering, $\preceq$ is by definition antisymmetric.

Thus it follows by definition of antisymmetry that $m = y$.

That is:

$y \preceq m \implies m = y$

which is precisely the definition of a minimal element.


Also see