Which of the following is used to denote the selection operation in relational algebra?

Relational Algebra is a __________ query language that takes two relations as input and produces another relation as an output of the query.

Which of the following is a fundamental operation in relational algebra?

For select operation the ________ appear in the subscript and the ___________ argument appears in the paranthesis after the sigma.

The ___________ operation, denoted by −, allows us to find tuples that are in one relation but are not in another.

Which is a unary operation: