What is the meaning of the notation $]a,b[$?

Question

I've seen the notation $]a,b[$ in several questions on this site, but I am not familiar with it. Can someone clue me in?

score 5 · Answer 1 · answered Dec 21 '14 at 23:41

5

It is the open interval $(a,b) = \{x \in \mathbb{R}: a<x<b\}$.

answered Dec 21 '14 at 23:41

user133281

score 3 · Accepted Answer · answered Dec 21 '14 at 23:47

3

The notation $]a,b[$ means the open interval $(a,b)$ and it's the Bourbaki notation.

answered Dec 21 '14 at 23:47

So give a reference to Bourbaki if you claim it to be Bourbaki notation. – Mister Benjamin Dover Dec 21 '14 at 23:48
Certainly Bourbaki invented many new notations but I'm not sure that they also invent the notation of open interval but at least I'm sure that they adopt it in their books. – Dec 21 '14 at 23:56
1

Reference(ish) for Bourbaki: http://hsm.stackexchange.com/q/142/564 (It's not really a reference since the answer over there just asserts it's due to Bourbaki.) – apnorton Dec 21 '14 at 23:56
This is the notation I learned and use in France. I didn't realize that it was due to Bourbaki, but indeed that would explain why we use a different notation – Jack Dec 22 '14 at 00:18

2 Answers2