more from Shaughan Lavine

### Single Idea 15914

#### [catalogued under 4. Formal Logic / F. Set Theory ST / 2. Mechanics of Set Theory / b. Terminology of ST]

Full Idea

A member m of M is an 'upper bound' of a subset N of M if m is not less than any member of N. A member m of M is a 'least upper bound' of N if m is an upper bound of N such that if l is any other upper bound of N, then m is less than l.

Gist of Idea

An 'upper bound' is the greatest member of a subset; there may be several of these, so there is a 'least' one

Source

Shaughan Lavine (Understanding the Infinite [1994], III.4)

Book Reference

Lavine,Shaughan: 'Understanding the Infinite' [Harvard 1994], p.53

A Reaction

[if you don't follow that, you'll have to keep rereading it till you do]