0 votes 0 votes Databases relational-calculus databases tuple-relational-calculus relational-algebra + – Parshu gate asked Dec 5, 2017 Parshu gate 976 views answer comment Share Follow See all 6 Comments See all 6 6 Comments reply Show 3 previous comments joshi_nitish commented Dec 5, 2017 reply Follow Share quntifier is missing on a and b, assuming it to be $\exists$ answer should be 4 P Q U 2 b 5 2 b 6 2 c 5 3 d 6 0 votes 0 votes Ashwin Kulkarni commented Dec 5, 2017 reply Follow Share 4 rows T.P T.Q T.U 2 b 5 2 b 6 2 c 5 3 d 6 1 votes 1 votes Shubhanshu commented Dec 5, 2017 reply Follow Share If we don't use $\exists$ before a and b then they are free variable and the above theory can also be written as {a.P, a.W, b.U / remaining query} or {a.P, b.Q, b.U / remaining query} is it correct? 0 votes 0 votes Please log in or register to add a comment.