Human: Why is it that a tuple of a row and column is called a relation? Assistant: 
That’s a good question. It’s because the row and column are a relation. In fact, it’s because the rows and columns are a relation that you can use the term relational algebra. A relation is a set of tuples. In fact, it’s a set of tuples and sets of sets of tuples, etc. The term relational algebra is used to describe the mathematical operations that can be performed on relations.