Consider the following table definition, where the primary keys are underlined. Give an expression in relational algebra for each of the following queries. Athlete (aID integer, aName string, ranking integer, age integer) Event (eID string, eName string, eLocation string) Competes (aID integer, eID string, sport string, year integer)

1. Find the names of athletes who have competed in event 1Sk8P (eiD = 1Sk8P)

2. Find the names of athletes who have competed in the event XGames (eName = XGames)

3. Find the names of the events an athlete named George competed in (aName = George)

4. Find the names of athletes who have competed in events named X Games and over the age of 25.