Movies(title, year, length, studioName)
A tuple(t,y,l,s) indicates that a movie with title t was produced by studio s in the year y, and the length (in minutes) of the movie was l.
Stars(starName, title, year)
A tuple(s,t,y) indicates that the star (i.e., actor or actress) with name s acted in a movie with title t in year y.
Express each of the following queries in relational algebra (not in SQL):
a) Find the title and year of every pair of movies that have at least one star in common.
b) Find the name of each star who never acted in more than one movie in any single year.
c) Find the name of each star who acted in every movie produced by the "Paramount" studio between 2000 and 2015.