# Can sets be bounded by infinity?

1. Jan 27, 2009

### Magenta

I cannot remember if infinity is an upper bound for a subset of R?
I think so, but I want to be sure before I use it in a proof.

2. Jan 28, 2009

### tiny-tim

Welcome to PF!

Hi Magenta ! Welcome to PF!

It depends what you mean by R.

Infinity isn't usually a member of R, and if it isn't then it can't be an upper bound.