*Question:*
Can we use the extended relational algebra, or just the core?

**Answer:**
You may use the extended algebra unless we say otherwise.

*Question:*
Should we assume relational algebra is an algebra of sets or bags?

**Answer:**
Sets, unless we ask for the bag version explicitly.

*Question:*
In problem 6, do we need to justify our answer?

**Answer:**
I forgot to require an explanation, but I think people should give a
brief explanation. It's not hard, once you see what the right answer is.

*Question:*
In problem 2(b), does ``any'' really mean ``exists''?

**Answer:**
No; the intention was coloquial.
We're really asking if the employee makes more than every manager.

*Question:*
How should we express our relational-algebra expressions?

**Answer:**
Any of the notations we used in class is OK: trees, plain old expressions, or
the linear sequence of assignments.