- #1

- 186

- 1

So do I just use the following definition: Suppse [itex] S [/itex] is an ordered set, and [itex] E \subset S [/itex]. If there exists a [itex] \beta \in S [/itex] such that [itex] x \leq \beta [/itex] for every [itex] x \in E [/itex], then [itex] \beta [/itex] is an upper bound for [itex] E [/itex], and similarly for lower bound?