IS2 Homework I Solutions IS2 Homework I Solutions

Question 1
(i) p= `` It is raining.'', q = ``I have an umbrella.'' (p Ù(Øq)) Ú(Øp)
(ii) p=``It is raining.'', q=``I can stay at home.'' (Øp) ® (Øq)

Question 2
(i)

pq Øq (Ø1) Ùp p ® ((Øq) Ùp)
T T F F F
T F T T T
F T F F T
F F T F T

(ii)

p q p® q (p ® q) Ùq [(p ® q) Ùq] ® p
T T T T T
T F F F T
F T T T F
F F T F T

Question 3
p=`` The two lines given are parallel.''
q=`` The two lines given have the same slope.''
Statement is p® q.

Converse (q ® p)
If the two lines given have the same slope, then they are parallel.

Inverse (Øp ® Øq)
If the two lines given are not parallel then they do not have the same slope.

Contrapositive ((Øq) ® (Øp))
If the two lines given do not have the same slope then they are not parallel.

Negation (Ø(p® q) º Ø(Øp Úq) º p Ù(Øq))
The two lines given are parallel and do not have the same slope.

Question 4
p=``Sandra finishes her work'', q=``It snows'', r=``Sandra goes to the basket ball game.''

p ® ((Øq) ® r).  (Øq).  Therefore (p ® r).

p q r Øq (Øq ® r) p® (Øq ® r) [p® (Øq ® r)] Ù(Øq)
TTTFTTF
TTFFTTF
TFTTTTT
TFFTFFF
FTTFTTF
FTFFTTF
FFTTTTT
FFFTFTT

p ® r { p® (Øq ® r) Ù(Øq)} ® (p ® r)
TT
FT
TT
FT
TT
TT
TT
TT

The following table shows this is a tautology, therefore the argument is valid.

Question 5
(i) For every item in the whole world if it is a cat then it is not a dog.
(ii) There exists some item in the whole world that is not a dog and not a cat.

Question 6

Ø(""y [P(x,y) ® Q(x,y)])
º
$x (Ø("y [P(x,y) ® Q(x,y)]))
º
$$y(Ø( [P(x,y) ® Q(x,y)]))
º
$$y(Ø( [(ØP(x,y)) ÚQ(x,y)]))
º
$$y[P(x,y) Ù(ØQ(x,y))]

Question 7
(i) False  (ii) False  (iii) True  (iv) False  (v) True

Question 8
(i) A ÈB = {1,2,3,5,6,{1,2}}
(ii) A ÇC = { 1,2,8}
(iii) B Ç[`C] = Æ
(iv) (A Ç[`B]) ÈC = E
(v) [`(([`B] È[`C]))] = {3,5,8}

Question 9
7 students played no games.


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On 6 May 1999, 15:10.