CIS 4930/6930: Programs, Functions, Strange Loops, and
Consciousness
Programs and Functions Assignment 2
1. (4 pts.) Which one of the following statements best captures the precise meaning
of the strong correctness predicate, "{P} S {Q} strongly"? (Circle ONE only.)
a. P must hold before S executes and Q must hold if S terminates.
b. {P} S {Q} is true unless Q could be false if S terminates.
c. If P holds before executing S, S must terminate in state Q.
d. If P holds before executing S, {P} S {Q} is true unless S could terminate with
Q being false.
e. {P} S {Q} is true unless Q is always false when S terminates, given that P
held before executing S.
2. (9 pts.) Consider the hypothesized invariant:
for the assertion:
Which of the following correctly identifies which of the while_do statement ROI
antecedents would hold when attempting to prove this assertion using the given
hypothesized invariant? (Circle ONE only.)
a. initialization only (6 pts.) e. initialization and finalization only (9 pts.)
b. preservation only (0 pts.) f. initialization and preservation only (3 pts.)
c. finalization only (6 pts.) g. initialization, preservation, and finalization (6 pts.)
d. preservation and finalization only (3 pts.) h. none of the antecedents would hold (3 pts.)
Partial credit points are indicated red for each alternative to the correct answer, e. As stated in
class, the given hypothesized invariant means: “Sum is equal to the sum of the first J elements
of array X – i.e., X[1]+X[2]+…+X[J]”. Therefore, the sum of the first 0 elements (=no elements)
is 0.
This study source was downloaded by 100000850872992 from CourseHero.com on 04-08-2023 16:31:14 GMT -05:00
https://www.coursehero.com/file/122497716/Assign-2-SOLNdocx/
Consciousness
Programs and Functions Assignment 2
1. (4 pts.) Which one of the following statements best captures the precise meaning
of the strong correctness predicate, "{P} S {Q} strongly"? (Circle ONE only.)
a. P must hold before S executes and Q must hold if S terminates.
b. {P} S {Q} is true unless Q could be false if S terminates.
c. If P holds before executing S, S must terminate in state Q.
d. If P holds before executing S, {P} S {Q} is true unless S could terminate with
Q being false.
e. {P} S {Q} is true unless Q is always false when S terminates, given that P
held before executing S.
2. (9 pts.) Consider the hypothesized invariant:
for the assertion:
Which of the following correctly identifies which of the while_do statement ROI
antecedents would hold when attempting to prove this assertion using the given
hypothesized invariant? (Circle ONE only.)
a. initialization only (6 pts.) e. initialization and finalization only (9 pts.)
b. preservation only (0 pts.) f. initialization and preservation only (3 pts.)
c. finalization only (6 pts.) g. initialization, preservation, and finalization (6 pts.)
d. preservation and finalization only (3 pts.) h. none of the antecedents would hold (3 pts.)
Partial credit points are indicated red for each alternative to the correct answer, e. As stated in
class, the given hypothesized invariant means: “Sum is equal to the sum of the first J elements
of array X – i.e., X[1]+X[2]+…+X[J]”. Therefore, the sum of the first 0 elements (=no elements)
is 0.
This study source was downloaded by 100000850872992 from CourseHero.com on 04-08-2023 16:31:14 GMT -05:00
https://www.coursehero.com/file/122497716/Assign-2-SOLNdocx/
