Consider the relational database of Figure 6.22 where the primary keys are underlined. Give an expression in tuple relational calculus for each of the following queries:
a. Find all employees who work directly for "Jones."
b. Find all cities of residence of all employees who work directly for "Jones."
c. Find the name of the manager of the manager of "Jones."
d. Find those employees who earn more than all employees living in the city "Mumbai."
