Consider the set of courses offered by a University; each of them has a (possibly empty) set of...

Consider the set of courses offered by a University; each of
them has a (possibly empty) set of prerequisite ones (i.e., courses that have
to be completed prior to enrollment to the current one); only titles are of
interest for courses. For each course several books may be recommended and some
books may be even recommended for several courses; only the title and the
(co)authors are of interest for books. For students, only first, middle, and
last name, birth date and place, completion degrees, and current enrollments
are of interest.

a. Design a DKRINF db scheme for this subuniverse and
provide a plausible instance of it with at least four rows per table.

b. Design and test for this instance SPJR expressions and
corresponding SQL statements for computing the subsets of:

(i) courses (title, precondition title) having at least two
preconditions;

(ii) courses (title) for which at least four students are
enrolled;

(iii)students (first, middle, and last name, birth date and
place) that enrolled to courses for which books containing “Mathematical Logic”
in their titles are recommended;

(iv) completions (student first, middle, and last name,
birth date and place, course title) for which course title is identical or
included in the title of at least one recommended book for that course.