Table schema:
CREATE TABLE prereq (course_id VARCHAR, prereq_id VARCHAR); CREATE TABLE course (title VARCHAR, course_id VARCHAR); CREATE TABLE course (course_id VARCHAR, title VARCHAR)

Question: Find the title of course whose prerequisite is course Differential Geometry.
SQL: SELECT title FROM course WHERE course_id IN (SELECT T1.course_id FROM prereq AS T1 JOIN course AS T2 ON T1.prereq_id = T2.course_id WHERE T2.title = 'Differential Geometry')