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This article discusses the application of the vOut and vIn strategies in logical proofs, particularly focusing on establishing goals and managing missing conditionals through new goal setups. It outlines specific proof methods for demonstrating implications, considering various logical conditions and connecting premises effectively. The guide walks through step-by-step proofs using the framework of logical inequalities and conditional statements, ensuring a comprehensive understanding of how to structure arguments and reach valid conclusions.
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Proofs Using vOut A v B A>G B>G G A v B G 1. V v -V A 2. V>-B A 3. -V>-N A -Bv-N GOAL Set up the vOut Strategy
Proofs Using vOut A v B A>G B>G G A v B G 1. V v -V A 2. V>-B A 3. -V>-N A -Bv-N GOAL ... by making the missing conditionals new goals.
Proofs Using vOut A v B A>G B>G G A v B G 1. V v -V A 2. V>-B A 3. -V>-N A V>(-Bv-N) GOAL -V>(-Bv-N) GOAL -Bv-N 1,?,? vO Prove the top goal using the >I Strategy
Proofs Using vOut A v B A>G B>G G A v B G 1. V v -V A 2. V>-B A 3. -V>-N A 4. V PA -Bv-N GOAL V>(-Bv-N) 4-? >I -V>(-Bv-N) GOAL -Bv-N 1,?,? vO Apply >O whenever you can.
Proofs Using vOut A v B A>G B>G G A v B G 1. V v -V A 2. V>-B A 3. -V>-N A 4. V PA -B 2,4 >O -Bv-N GOAL V>(-Bv-N) 4-? >I -V>(-Bv-N) GOAL -Bv-N 1,?,? vO ... and your goal comes by vIn
Proofs Using vOut A v B A>G B>G G A v B G 1. V v -V A 2. V>-B A 3. -V>-N A 4. V PA 5. -B 2,4 >O 6. -Bv-N 5 vI 7. V>(-Bv-N) 4-6 >I -V>(-Bv-N) GOAL -Bv-N 1,7,? vO Now use >In to obtain your second goal.
Proofs Using vOut A v B A>G B>G G A v B G 1. V v -V A 2. V>-B A 3. -V>-N A 4. V PA 5. -B 2,4 >O 6. -Bv-N 5 vI 7. V>(-Bv-N) 4-6 >I 8. -V PA -Bv-N GOAL -V>(-Bv-N) 8-? >I -Bv-N 1,7,? vO Apply >O whenever you can.
Proofs Using vOut A v B A>G B>G G A v B G 1. V v -V A 2. V>-B A 3. -V>-N A 4. V PA 5. -B 2,4 >O 6. -Bv-N 5 vI 7. V>(-Bv-N) 4-6 >I 8. -V PA -N 3,8 >O -Bv-N GOAL -V>(-Bv-N) 8-? >I -Bv-N 1,7,? vO ... and your goal comes by vIn
Proofs Using vOut A v B A>G B>G G A v B G 1. V v -V A 2. V>-B A 3. -V>-N A 4. V PA 5. -B 2,4 >O 6. -Bv-N 5 vI 7. V>(-Bv-N) 4-6 >I 8. -V PA 9. -N 3,8 >O 10. -Bv-N 9 vI 11. -V>(-Bv-N) 8-10>I 12. -Bv-N 1,7,11 vO The proof is now complete.
Proofs Using vOut A v B A>G B>G G A v B G 1. A&(BvC) A (A&B)v(A&C) GOAL Do &Out whenever you can
Proofs Using vOut A v B A>G B>G G A v B G 1. A&(BvC) A 2. A 1 &O 3. B v C 1 &O (A&B)v(A&C) GOAL Set up the vOut Strategy
Proofs Using vOut A v B A>G B>G G A v B G 1. A&(BvC) A 2. A 1 &O 3. B v C 1 &O (A&B)v(A&C) 3,?,? vO Set the missing conditionals as new goals.
Proofs Using vOut A v B A>G B>G G A v B G 1. A&(BvC) A 2. A 1 &O 3. B v C 1 &O B>[(A&B)v(A&C)] GOAL C>[(A&B)v(A&C)] GOAL (A&B)v(A&C) 3,?,? vO Use >In to prove the first goal.
Proofs Using vOut A v B A>G B>G G A v B G 1. A&(BvC) A 2. A 1 &O 3. B v C 1 &O 4. B PA (A&B)v(A&C) GOAL B>[(A&B)v(A&C)] 4-? >I C>[(A&B)v(A&C)] GOAL (A&B)v(A&C) 3,7,? vO Prove A&B so that you can use vIn to obtain the goal.
Proofs Using vOut A v B A>G B>G G A v B G 1. A&(BvC) A 2. A 1 &O 3. B v C 1 &O 4. B PA 5. A&B 2,4 &I (A&B)v(A&C) GOAL B>[(A&B)v(A&C)] 4-? >I C>[(A&B)v(A&C)] GOAL (A&B)v(A&C) Now the subproof can be completed with vIn.
Proofs Using vOut A v B A>G B>G G A v B G 1. A&(BvC) A 2. A 1 &O 3. B v C 1 &O 4. B PA 5. A&B 2,4 &I 6. (A&B)v(A&C) 5 vI 7. B>[(A&B)v(A&C)] 4-6 >I C >[(A&B)v(A&C)] GOAL (A&B)v(A&C) 3,7,? vO Now set up the >In Strategy to prove the second goal.
Proofs Using vOut A v B A>G B>G G A v B G 1. A&(BvC) A 2. A 1 &O 3. B v C 1 &O 4. B PA 5. A&B 2,4 &I 6. (A&B)v(A&C) 5 vI 7. B>[(A&B)v(A&C)] 4-6 >I 8. C PA (A&B)v(A&C) GOAL C>[(A&B)v(A&C)] 8-? >I (A&B)v(A&C) 3,7,? vO This subproof can be completed in the same way.
Proofs Using vOut A v B A>G B>G G A v B G 1. A&(BvC) A 2. A 1 &O 3. B v C 1 &O 4. B PA 5. A&B 2,4 &I 6. (A&B)v(A&C) 5 vI 7. B >[(A&B)v(A&C)] 4-6 >I 8. C PA 9. A&C 2,8 &I 10. (A&B)v(A&C) 9 vI 11. C >[(A&B)v(A&C)] 8-10 >I 12. (A&B)v(A&C) 3,7,11 vO The proof is now complete.