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Mauro ALLEGRANZA
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Hint

Assume S and derive R ∨ P from 1st premise.

Now two sub-proofs, for -elim:

  1. Assume R and derive Q ∨ R by -intro, and it is done.

  2. Assume P and derive ¬R → Q from 2nd premise.

Now use R ∨ ¬R (Excluded Middle) for a new -elim:

2.1) Assume R and derive Q ∨ R.

2.2) Assume ¬R and derive Q from ¬R → Q and then derive Q ∨ R.

Having derived Q ∨ R in each case, we can conclude with:

S → (Q ∨ R)

by -intro.

Hint

Assume S and derive R ∨ P from 1st premise.

Now two sub-proofs, for -elim:

  1. Assume R and derive Q ∨ R by -intro, and it is done.

  2. Assume P and derive ¬R → Q from 2nd premise.

Now use R ∨ ¬R (Excluded Middle) for a new -elim:

2.1) Assume R and derive Q ∨ R.

2.2) Assume ¬R and derive Q from ¬R → Q and derive Q ∨ R.

Having derived Q ∨ R in each case, we can conclude with:

S → (Q ∨ R)

by -intro.

Hint

Assume S and derive R ∨ P from 1st premise.

Now two sub-proofs, for -elim:

  1. Assume R and derive Q ∨ R by -intro, and it is done.

  2. Assume P and derive ¬R → Q from 2nd premise.

Now use R ∨ ¬R (Excluded Middle) for a new -elim:

2.1) Assume R and derive Q ∨ R.

2.2) Assume ¬R and derive Q from ¬R → Q and then derive Q ∨ R.

Having derived Q ∨ R in each case, we can conclude with:

S → (Q ∨ R)

by -intro.

Source Link
Mauro ALLEGRANZA
  • 41.3k
  • 3
  • 41
  • 92

Hint

Assume S and derive R ∨ P from 1st premise.

Now two sub-proofs, for -elim:

  1. Assume R and derive Q ∨ R by -intro, and it is done.

  2. Assume P and derive ¬R → Q from 2nd premise.

Now use R ∨ ¬R (Excluded Middle) for a new -elim:

2.1) Assume R and derive Q ∨ R.

2.2) Assume ¬R and derive Q from ¬R → Q and derive Q ∨ R.

Having derived Q ∨ R in each case, we can conclude with:

S → (Q ∨ R)

by -intro.