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

Question: What is the course title of the prerequisite of course Mobile Computing?
SQL: SELECT title FROM course WHERE course_id IN (SELECT T1.prereq_id FROM prereq AS T1 JOIN course AS T2 ON T1.course_id = T2.course_id WHERE T2.title = 'Mobile Computing')