TRC in database

Question

How does the evaluation will be done?

Comments

assuming, a and b are bounded by there exists quantifier($\exists$), result of query will be,

(2,b,5) (2,b,6) (2,c,5) (3,d,6)

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4 tupples in result

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Check for each value of W in R, check Q in S.where ever match,(It is join using values of R and Q) take down P,Q,U of that tuple as an output.

4 rows will be returned.