2. (5 points each) Write the following queries in relational algebra, using the schema provided above. If a query is long, feel free to break it up into a series of queries with intermediate answers stored in temporary relations (e.g. "let temp = . *) You can use abbreviations for Relational Algebra symbols such as S for SELECTION, P for PROJECTION, * for NATURAL JOIN,-for SET DIFFERENCE . Your queries must not be "state-dependent", that is, they should work without modification even if another instance of the database is given. . (d) Find the postID, Content and the FullName of the post creator, for each post commented by "Jenny_27" that is in "Mike_34" wall. (e) Retrieve the names of all the Persons who have at least a post without likes and without comments