===== Equivalence class =====
==== Set ====
| @#55CCEE: context     | @#55CCEE: $X$ |
| @#55CCEE: context     | @#55CCEE: $x\in X$ | 
| @#55CCEE: context     | @#55CCEE: $\sim\in\text{Equiv}(X) $ |
| @#FFBB00: definiendum | @#FFBB00: $ y\in [x]_\sim $ |
| @#55EE55: postulate   | @#55EE55: $y\sim x$ |

==== Ramifications ====
=== Discussion ===
For some combinatorics on the number of possible equivalence classes, see [[http://en.wikipedia.org/wiki/Bell_number|Bell number (Wikipedia)]].
=== Reference ===
Wikipedia: [[http://en.wikipedia.org/wiki/Equivalence_class|Equivalence class]]
==== Parents ====
=== Context ===
[[Equivalence relation]]