# => SELECT users.name FROM users GROUP BY users.name
# => SELECT users.name FROM users GROUP BY users.name
```
```
The best property of the Relational Algebra is its "composability", or closure under all operations. For example, to restrict AND project, just "chain" the method invocations:
The best property of arel is its "composability", or closure under all operations. For example, to restrict AND project, just "chain" the method invocations: