Proof Strategy for Sentential Logic

  1. Assume the given premises
  2. Try to apply rules to generate desired conclusion resting only on given premises (Be methodical!)
  3. If you need to make an additional assumption, LOOK AT WHAT YOU WANT TO PROVE not at what you have already established and make the assumption according to the hints below, and return to step 2

Proof Strategy for Predicate Logic

The general strategy for doing proofs in predicate logic incorporates the strategy for proofs in sentential logic.
  1. If you have a Universal sentence, use Universal Elimination to derive one or more instances as needed.
  2. If you have an existential formula, assume an instance (for Existential Elimination).
  3. Apply rules until you get to the desired conclusion or need to make an assumption.
  4. If you need to make an assumption, look at what you are trying to prove and use the hints above in conjunction with these below: