Given the relational functional dependencies x —> w ; x ->y

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PGCET CSE Exam (Karnataka) 2011 click here to view all questions

Given the relational functional dependencies x —> w ; x ->y ; y -> z and z -> pq which of the following is NOT VALID ?

Ax -> z

Bx ->wy

Cy —> pq

Dw ->z

Akilesh Kharvi ? Dec 8 '2016 at 21:33

Answer:w ->z

Explanation:

If X→Y and Y→Z then X→Z so it is valid.
If X→W and X→Y then X→WY so it is valid.
If Y→Z and Z→PQ then Y→PQ so it is valid.
w not implies anything so w ->z is not valid.
so answer is w->Z

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Answer:w ->z Explanation: If X→Y and Y→Z then X→Z so it is valid. If X→W and X→Y then X→WY so it is valid. If Y→Z and Z→PQ then Y→PQ so it is valid. w not implies anything so w ->z is not valid. so answer is w->Z Akilesh Kharvi ? answered Dec 8 '2016 at 21:33 All Comments

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