Let A = {1,5,8,9). Are the following relations on A reflexive? 1. {(9,8), (8, 1), (1, 5), (9, 9), (8, 8)} 2. {(8,5), (9, 9), (5, 1), (1, 1)} 3. {(9, 1), (5,9), (9, 9), (8, 8), (1, 1)} ? ? ? V V 13 ? ? 4. {(9,5), (1,9), (5,8), (8, 8), (1, 1)} ✓ 5. {(9, 9), (8, 8), (1, 1), (5, 5), (9, 5), (5, 1)} 6. {(9,9), (8, 8), (1, 1), (5, 5), (8,5)}

Let A = {1,5,8,9). Are the following relations on A reflexive? 1. {(9,8), (8, 1), (1, 5), (9, 9), (8, 8)} 2. {(8,5), (9, 9), (5, 1), (1, 1)} 3. {(9, 1), (5,9), (9, 9), (8, 8), (1, 1)} ? ? ? V V 13 ? ? 4. {(9,5), (1,9), (5,8), (8, 8), (1, 1)} ✓ 5. {(9, 9), (8, 8), (1, 1), (5, 5), (9, 5), (5, 1)} 6. {(9,9), (8, 8), (1, 1), (5, 5), (8,5)}

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

See similar textbooks

Similar questions

8 of 40 Let R(A, B, C, D, E, F) be a relation with FD's: {D → C, C → D, D – E, C → E, E → AD, AF → E, D → B}. Which of the following statements is correct? Select one: O R is not in 3NF but in BCNF. Ris not in 3NF and not in BCNF. O Ris in 3NF but not in BCNF. O R is in 3NF and in BCNF.
Solve the following:
23 of 40 Let R(A, B, C, D, E, F) be a relation with FD's: {D → CE, C → BDE, E → AD, AF → E, B → DF}. Which of the following statements is correct? Select one: O Ris in BCNF but not in 3NF. O Ris in 3NF but not in BCNF. O Ris not in 3NF and not in BCNF. O R is in 3NF and in BCNF.
For each of the following pairs of expressions, give instances of relations thatshow the expressions are not equivalent. ΠA(r − s) and ΠA(r) − ΠA(s).
The class I'm taking is computer science discrete structures. I am completely stuck. Please help! If you can please add an explanation with answer so I can better understand . Problem is attached! Thank you!
Given the relations U and T below, use ordered pair notation to express the relation To U. ToU = {Ex: (a, b), (b, c) b U a b T
Consider the relation prereg in the University Database and its transitive closure defined in Section 5.4 of the textbook. Consider the recursive query in Figure 5.16 that outputs this transitive closure. Write a recursive query that finds all direct or indirect prerequisite of BIO-301. Output a table with one column that contains the IDs of all such prerequisites. Note that your query must work correctly not only for the given instance of prereg, but also for all possible instances. Run this query.
7 PLEASE TYPE ONLY***
no relatIYCS 3. Give a Z expression for the set of all people in the database who have no siblings in the database. arations through which
a
3,
Given the relation T below, use ordered pair notation to express the relation To T. ToT { Ex: (a, b), (b, c) b Lo a с } T