===== Extended real number line =====
==== Set ====
| @#55EE55: postulate   | @#55EE55: $ \overline{\mathbb R} \equiv \mathbb R\cup\{-\infty,\infty\} $ |

>todo: model $-\infty$ and $\infty$

==== Discussion ====
==== Reference ====
Wikipedia: [[http://en.wikipedia.org/wiki/Extended_real_number_line|Extended real number line]]

==== Parents ====
=== Context ===
[[Real number]]