Math and science::Analysis::Tao::09. Continuous functions on R

# Intervals (of the reals), definition

Let $$a, b \in \mathbb{R}^*$$ be extended real numbers.

We define the closed interval $$[a, b]$$ by

[...]

We define the half-open intervals $$[a, b)$$ and $$(a, b]$$ by

[...] and [...]

And we define the open interval $$(a, b)$$ by

[...]

We call $$a$$ the [...] and $$b$$ the [...].