Hello there.

I am working on some relational algebra for my database design class (as a precursor to SQL), and I'm getting stumped by some problems.

Before I get to the problems I need help with, here is the schema that I am working with:
Category(class, function, country, num_guns, max_altitude, max_fuel)
Planes(pname, class, year)
DogFights(dname, date)
Outcomes(pname, dname, result)
The problems I'm having trouble with are the following:
List the name and year of maiden flight for the plane/s that fought in most battles that Hard Luck also fought in.

List all planes that won more battles than they lost.

I know that for both of these, I'll have to start off with a join, as I know I have to reference data from more than 1 relation.

Thanks in advance for the help!