Introductory Logic 
Quiz #5

October
14, 2005

Name: ________________________ 
R. Hammack

Score: _________

(a)  ( S • R ) ⊃ ( ~S ≡ R ) 
(

S

•

R

)

⊃

(

~

S

≡

R

)

T

T

T

F


F

T

F

T


T

F

F

T

F

T

T

F


F

F

T

T

T

F

T

T


F

F

F

T

T

F

F

F

(b)  ~( R • S ) 
~

(

R

•

S

)

F

T

T

T


T

F

F

T


T

T

F

F


T

F

F

F

2.  Is statement (a) from Question 1 contingent, tautologous or selfcontradictory? 
CONTINGENT
3.  Are statements (a) and (b) from Question 1 logically equivalent, contradictory, consistent or inconsistent? List all that apply. 
LOGICALLY EQUIVALENT and CONSISTENT
4. Decide if the following argument is valid or invalid by writing out its truth table.
~(G • M) 
M ∨ ~G 

~G 
~

(

G

•

M

)

/

M

∨

~G

//

~

G

F

T

T

T


T

T

FT


F

T


T

T

F

F

F

F

FT

F

T


T

F

F

T

T

T

TF

T

F


T

F

F

F

F

T

TF

T

F

VALID, because in every line where the premises are both true (the 3rd and 4th) the conclusion is true also.