Chapter 7 Answer Key to Select Chapter Exercises

Exercise 7.1

2. Conditional. Components: One is lucky, a solitary fantasy can totally transform one million realities; →
3. Disjunction. Components: He didn’t get my message, he’s ignoring me; v
4. NO conjunction, disjunction, or conditional; simply negation.

Exercise 7.2
2. y x
3. p v q
6. ~r
7. p & ~q
10. ~y & ~z
15. ~a & b

Exercise 7.3
3. False
5. True
7. True
10. True

Exercise 7.4
1. True
3. False
7. True
10. True

Exercise 7.5
1. If alligators are reptiles, then alligators have scales.
7. Water is wet, and fire is not cold.
8. Either the bakery is not open, or the pub is not open.
10. If the day goes well, then we will not regret our efforts.

Exercise 7.6
3. p v q
4. p q
7. ~p & ~q
10. p & ~q

Exercise 7.7
1. pq

p

q

p q

T

T

T

T

F

F

F

T

T

F

F

T


5. p v q

p

q

p v q

T

T

T

T

F

T

F

T

T

F

F

F


7. ~p q

p

q

~p

~pq

T

T

F

T

T

F

F

T

F

T

T

T

F

F

T

F


10. ~~ p v q

p

q

~~p

~~p v q

T

T

T

T

T

F

T

T

F

T

F

T

F

F

F

F


Exercise 7.8
2. Invalid
p v q
q
~ p

p

q

p v q

q

~p

T

T

T

T

F

T

F

T

F

F

F

T

T

T

T

F

F

F

F

T



5. Invalid
p q
~ p
q


p

q

p q

~p

q

T

T

T

F

T

T

F

F

F

F

F

T

T

T

T

F

F

T

T

F



6. Invalid
q r
pq
q


p

q

r

q r

p q

q

T

T

T

T

T

T

T

T

F

F

T

T

T

F

T

T

F

F

T

F

F

T

F

F

F

T

T

T

T

T

F

T

F

F

T

T

F

F

T

T

T

F

F

F

F

T

T

F



8. Valid
a v (b & c)
~ (b & c)
a

a

b

c

(b & c)

a v(b&c)

~ (b & c)

a

T

T

T

T

T

F

T

T

T

F

F

T

T

T

T

F

T

F

T

T

T

T

F

F

F

T

T

T

F

T

T

T

T

F

F

F

T

F

F

F

T

F

F

F

T

F

F

T

F

F

F

F

F

F

T

F



9. Valid
pq
p → (p & q)

p

q

p & q

pq

p(p&q)

T

T

T

T

T

T

F

F

F

F

F

T

F

T

T

F

F

F

T

T



10. Valid
xy
y
z
xz

x

y

z

x y

y z

x z

T

T

T

T

T

T

T

T

F

T

F

F

T

F

T

F

T

T

T

F

F

F

T

F

F

T

T

T

T

T

F

T

F

T

F

T

F

F

T

T

T

T

F

F

F

T

T

T



13. Valid
(p v q) → (p & q)
p & q
p v q


p

q

(p v q)

(p & q)

(p v q) (p & q)

p & q

p v q

T

T

T

T

T

T

T

T

F

T

F

F

F

T

F

T

T

F

F

F

T

F

F

F

F

T

F

F



15. Valid
(d v e) → (d & e)
~ (d v e)
~ (d & e)

d

e

(d v e)

(d & e)

(d v e) → (d & e)

~ (d v e)

~ (d & e)

T

T

T

T

T

F

F

T

F

T

F

F

F

T

F

T

T

F

F

F

T

F

F

F

F

T

T

T



16. Valid
(pq) → (pr)
~ (pq)
~ r
p


p

q

r

(p q)

(p r)

(pq) → (pr)

~ (pq)

~r

p

T

T

T

T

T

T

F

F

T

T

T

F

T

F

F

F

T

T

T

F

T

F

T

T

T

F

T

T

F

F

F

F

T

T

T

T

F

T

T

T

T

T

F

F

F

F

T

F

T

T

T

F

T

F

F

F

T

T

T

T

F

F

F

F

F

F

T

T

T

F

T

F


Exercise 7.9
1. Valid
p q
~ p r
~ p
r

p

q

r

~ p r

~ p

r

T

T

T

T

F

T

T

T

F

T

F

F

T

F

T

T

F

T

T

F

F

T

F

F

F

T

T

T

T

T

F

T

F

F

T

F

F

F

T

T

T

T

F

F

F

F

T

F

(Including the first premise, p q, in the truth table changes nothing.)

2. Valid
p q
~q
~ p

p

q

p q

~q

~p

T

T

T

F

F

T

F

F

T

F

F

T

T

F

T

F

F

T

T

T



6. Invalid
f ~ s
~s p
p

f

s

p

f ~s

~s p

p

T

T

T

F

T

T

T

T

F

F

T

F

T

F

T

T

T

T

T

F

F

T

F

F

F

T

T

T

T

T

F

T

F

T

T

F

F

F

T

T

T

T

F

F

F

T

F

F



7. Valid
p q
p
q

p

q

p q

p

q

T

T

T

T

T

T

F

F

T

F

F

T

T

F

T

F

F

T

F

F


10. Valid
w v ~ w
~ w ~ r
w r
~ w
~ r

w

r

w v ~ w

~ w → ~ r

w r

~ w

~ r

T

T

T

T

T

F

F

T

F

T

T

F

F

T

F

T

T

F

T

T

F

F

F

T

T

T

T

T



Exercise 7.10
5. Invalid
p q
~ p
q

T

T

F

p q

~ p

q

F       F

F

F


10. Valid
xy
yz
xz

F

T

F

x y

y → z

x → z

T      F

F    F

T      F     


18. Invalid
~ (d & e)
e v f
~ d & f

T

T

F

~ (d & e)

e v f

~ d & f

T    F

F    T

T    T



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