SOLUTION: Give a formal proof of the validity of the following arguments. State the inference rule you used to create each new premise. Show all your work. . �There are only three pos

Question 1115946: Give a formal proof of the validity of the following arguments. State the inference rule you used to create each new premise. Show all your work.

. �There are only three possibilities: either your sister is mad or she is telling lies, or she is telling the truth. You know she does not tell lies, and she is obviously not mad, so we must conclude that she is telling the truth.�
C. S. Lewis
Answer by solver91311(24713) (Show Source): You can put this solution on YOUR website!


1.  (A + B) + C 
2.  ~A
3.  ~B          | C

4.  ~A * ~B     2, 3  Conjunction Introduction
5.  ~(A + B)    4     DeMorgan
6.  C           1, 5  Disjunctive Syllogism

John

My calculator said it, I believe it, that settles it

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