Anonymous asked in Science & MathematicsMathematics · 5 years ago

Rules of inference and equivalence question?


s v r Premise

p Premise

r -> ~q Premise

p -> q Premise

Prove: s v t

I was able to do the harder ones but not this one and its supposedly the easiest...

1 Answer

  • 5 years ago
    Favorite Answer

    Using this reference set of rules of inference:

    1. S v R

    2. P

    3. R -> ~Q

    4. P -> Q

    5. Q [4 and 1, modus ponens]

    6. ~R [3 and 5, modus tollens]

    7. R v S [1, commutation]

    8. S [7 and 6, disjunctive syllogism]

    9, S v T [8, addition]

    You can count on the addition rule coming into play when you see a variable that wasn't anywhere in the premises.

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