Given a binary relation from to , its opposite relation (or dual, or inverse, or converse, etc) is a relation from to as follows:
- is -related to if and only if is -related to .
Note that .
The operation is part of the requirements for Rel to be an allegory.
If is a function thought as a functional entire relation, then is also a function if and only if is a bijection; in that case, is the inverse of .
More generally, we have the following:
|If is …||then is …|
Revised on January 10, 2012 07:37:17
by Toby Bartels