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| Question 516109:  Determine which, if any, of the three statements are equivalent.
 I) If my car does not start, then I will not make it to work on time.
 II) If my car does not start, then I will make it to work on time.
 III) Either my car starts or I will make it to work on time.
 Answer by Edwin McCravy(20064)
      (Show Source): 
You can put this solution on YOUR website! 
Let s = "My car does not start."
Let w = "I will make it to work on time."
I) If my car does not start, then I will not make it to work on time.
That's ~s->~w
s  w  ~s  ~w  ~s -> ~w
T  T   F   F      T
T  F   F   T      T
F  T   T   F      F
F  F   T   T      T
II) If my car does not start, then I will make it to work on time.
That's ~s -> w
 
s  w  ~s  ~s -> w
T  T   F     T
T  F   F     T
F  T   T     T
F  F   T     F
III) Either my car starts or I will make it to work on time.
That's s V w
s  w  s V w
T  T    T
T  F    T    
F  T    T    
F  F    F    
II and III are equivalent because they have the same truth table,
TTTF.  
Or you can prove it because 
(p->q) <=> (~pVq) 
Let p = ~s and q = w, then
(~s->w) <=> (~(~s) V w)
(~s->w) <=> (s V w)
Edwin
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