Selecting DISTINCT rows in relational algebra

Question

There is a DISTINCT operator in SQL. However, I have an assignment in which I need to get some distinct values from a table, and I can only use relational algebra. Is there

Answer 1

Relational projections always return distinct tuples so DISTINCT is never needed. Duplicate tuples are not permitted in the RA - that being one major difference between the relational model and the SQL model.