===== Non-negative real number =====
==== Set ====
| @#FFBB00: definiendum | @#FFBB00: $ r \in\mathbb R_+ $ |
| @#55EE55: postulate   | @#55EE55: $ r \ge 0 $ |

==== Discussion ====
==== Reference ====
Wikipedia: [[http://en.wikipedia.org/wiki/Real_number|Real number]]
==== Parents ====
=== Subset of ===
[[Real number]]