The properties of relational algebra (commutativity, associativity, distribution) allow us to take a relational algebra expression and transform/rewrite it into another one which is logically equivalent. However, I am struggling to find any such properties as far as the grouping operator Ɣ is concerned.
I am not sure but I think Ɣ is derived from the other relational operators? Is this correct? I would suppose that if this is correct, then it explains why it is harder to find such properties. That being said, Ɣ (GROUP BY) remains a very important operator, so how can one reason about its properties in relational algebra? Has this been done before?