Question

In: Computer Science

Which of the following statements is true? Note that more than one of the statements may...

Which of the following statements is true? Note that more than one of the statements may be true.

a. Every relation that is in 3NF is in 2NF.

b. A relation that is in 2NF, and that has a non-primary-key attribute that is functionally dependent on another non-primary-key attribute is not in 3NF.

c. A relation that is in 2NF, and that has a non-primary-key attribute that is transitively functionally dependent on the primary key is not in 3NF.

Which of the following statements is true? Note that more than one of the statements may be true.

a. If A → B and C → D then B ∪ D is fully functionally dependant on A ∪ C, where X ∪ Y means the merge (or union) of X and Y.

b. If A → B and C→ D then A ∪ C→ B ∪ D, where X \cup∪ Y means the merge (or union) of X and Y.

c. If A is fully functionally dependant on B then B is fully functionally dependant on A.

d. If A → B then B → A.

Expert Solution

a True

b false

c true

Explanation:

A relation schema R is in third normal form (3NF) if it is in 2NF and no non-prime attribute A in R is transitively dependent on the primary key.

a false

b True

Explanation

By rule in Composition:

If P holds Q (P → Q) and A holds B (A → B), then PA → QB.

C true

Explanation

The term full functional dependency (FFD) is used to indicate the minimum set of attributes in of a functional dependency (FD). In other words, the set of attributes X will be functionally dependent on the set of attributes Y if the following conditions are satisfied:

X is functionally dependent on Y and

X is not functionally dependent on any subset of Y.

In relation ASSIGN of table it is true that

FD: {EMP-ID,PROJECT, PROJECT-BUDGET} -> {YRS-SPENT-BY-EMP-ON PROJECT}

The values of EMP-ID, PROJECT and PROJECT-BUDGET determine a unique value of YRS-SPENT-BY-EMP-ON-PROJECT. However, it is not a full functional dependency because neither the EMP-ID -> YRS-SPENT-BY-EMP-ON-PROJECT nor the PROJECT -> YRS-SPENT-BY-EMP-ON-PROJECT holds true.

In fact, it is sufficient to know only the value of a subset of {EMP-ID, PROJECT, PROJECTBUDGET), namely, {EMP-ID, PROJECT}, to determine the YRS-SPENT-BY-EMP-ON PROJECT. Thus, the correct full functional dependency (FFD) can be written as:

FD: {EMP-ID,PROJECT} -> {YRS-SPENT-BY-EMP-ON-PROJECT}

d false

venereology answered 1 month ago

A) Which of the following statements are true? Note that there may be more than one...

A) Which of the following statements are true? Note that there may be more than one correct answer; select all that are true. As the p-value increases, the evidence against the null hypothesis also increases. In hypothesis testing, if the p-value is sufficiently small, then the null hypothesis can be rejected in favour of the alternate hypothesis. If the null hypothesis is true, then the p-value will always be greater than 0.1. If the null hypothesis is false, then the...

Which of the following statements are TRUE? Note that there may be more than one correct...

Which of the following statements are TRUE? Note that there may be more than one correct answer; select all that are true. There are countably infinite values of X in a continuous uniform distribution. For a continuous uniform distribution defined on the interval [a,b], P(X < a) and P(X > b) is undefined. The mean and the variance of a continuous uniform random variable are the same. In a continuous uniform distribution, the mean and the median are the same....

Which of the following statements are true? There may be more than one true statement. A....

Which of the following statements are true? There may be more than one true statement. A. Any linear combination of vectors can always be written in the form Ax for a suitable matrix A and vector x. B. Every matrix equation Ax=b corresponds to a vector equation with the same solution set. C. If the echelon form of the augmented matrix [A | b][A | b] has a leading entry in every row, then the equation Ax=b is inconsistent. D....

Which of the following statements regarding dissociation is true:(might be more than one answer) - is...

Which of the following statements regarding dissociation is true:(might be more than one answer) - is always symptomatic of a dissociative disorder - dissociation can be a symptom of a stress-related disorder - most often affects semantic memory - dissociation often occurs during a traumatic event

Which of the following statements concerning the variance are correct? (NOTE: THERE CAN BE MORE THAN...

Which of the following statements concerning the variance are correct? (NOTE: THERE CAN BE MORE THAN ONE CORRECT ANSWER) a.The larger the variance, the greater the total risk of the investment. b.If a stock portfolio is well-diversified, then the portfolio variance may be less than the variance of the least risky stock in the portfolio. c.The larger the variance, the smaller the standard deviation. d.The larger the variance, the more the actual returns tend to differ from the average return....

1. What statements about muscle cells and ATP are TRUE? There may be more than one...

1. What statements about muscle cells and ATP are TRUE? There may be more than one answer. Select one or more: a. Muscle cells involved in aerobic metabolism have longer endurance and have greater force generating capacity than muscles involved in anaerobic metabolism. b. Muscle cells involved in aerobic metabolism have longer endurance but have smaller muscle mass than muscles involved in anaerobic metabolism. c. When muscle cell is at work, creatine kinase will convert ADP + creatine into ATP...

Which of the following is/are true about FUTA obligations? (You may select more than one answer....

Which of the following is/are true about FUTA obligations? (You may select more than one answer. Single click the box with the question mark to produce a check mark for a correct answer and double click the box with the question mark to empty the box for a wrong answer. Any boxes left with a question mark will be automatically graded as incorrect.) FUTA is subject to a 5.4 percent reduction based on employer and state factors.unanswered FUTA applies to...

Which of the following statements are true? Multiple answers: You can select more than one option...

Which of the following statements are true? Multiple answers: You can select more than one option A If unemployment benefits are increased¸ the minimum cost of a unit of effort for the employer will rise. B If the wage doesn’t change¸ employees will work harder in periods of high unemployment. C If workers continue to receive benefits however long they remained unemployed¸ an increase in the level of unemployment will have no effect on the best response curve. D If...

Explain (in no more than two paragraphs for each) which of the following statements are true...

Explain (in no more than two paragraphs for each) which of the following statements are true or false. A. The traditional liquidity premium theory states that long-term interest rates are greater than the average of current and expected future short-term interest rates .B. According to the market segmentation theory, short-term investors will not normally switch to intermediate- or long-term investments. C. According to the liquidity premium theory, investors preferring long-term bonds over short-term bonds would require lower liquidity premium.

Which of the following statements always apply to corporations? (You may select more than one answer. Single...

Which of the following statements always apply to corporations? (You may select more than one answer. Single click the box with the question mark to produce a check mark for a correct answer and double click the box with the question mark to empty the box for a wrong answer. Any boxes left with a question mark will be automatically graded as incorrect.) Unlimited liabilityunchecked Limited lifeunchecked Ownership can be transferred without affecting operationsunchecked Managers can be fired with no effect...