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

2.1k Views Asked by Bumbble Comm At 11 Apr 2026 - 9:23

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?

There are 2 best solutions below

user63181 On 21 Dec 2014 - 11:47 BEST ANSWER

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

Bumbble Comm On 21 Dec 2014 - 11:41

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