Can sets be bounded by infinity?

[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.

 

[tiny-tim]

Welcome to PF!

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.

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.