Rename (relational algebra)

In relational algebra, a rename is a unary operation written as formula_1 where:
The result is identical to except that the attribute in all tuples is renamed to . For an example, consider the following invocation of on an relation and the result of that invocation:
Formally, the semantics of the rename operator is defined as follows:
where formula_3 is defined as the tuple , with the attribute renamed to , so that: