Can Modus Ponens and Substitution Solve This Complex Logic Problem?

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The discussion focuses on proving the logical expression q -> r -> [ [ p -> q ] -> [ p -> r ] ] using modus ponens and substitution, alongside three axioms. The axioms utilized are: 1) p -> [ q -> p ], 2) s -> [ p -> q ] -> [ [s -> p] -> [ s -> q ] ], and 3) p -> f -> f -> p, where f represents "false." Participants explore the implications of these axioms and substitutions to derive the desired conclusion, emphasizing the importance of understanding the relationships between p, q, and r.

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  • Understanding of modus ponens in propositional logic
  • Familiarity with logical axioms and their applications
  • Knowledge of substitution in logical proofs
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JustNick
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Using only modus ponens or substitution. Prove:
q -> r -> [ [ p -> q ] -> [ p -> r ] ]

using the three axioms:
1) p -> [ q -> p ]
2) s -> [ p-> q ] -> [ [s -> p] -> [ s -> q ] ]
3) p -> f -> f -> p

where the symbol f is "false."

I am having the hardest time trying to solve this proof, any point in the right direction is appreciated.
 
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If p then it follows from 2). (s≡p ; p≡q ; q≡r) But isn't 3) just p? I guess my understanding of 3) is f.
May I conclude f → (p → f) by 1) and then f → p by 3)? If so I'm done by 2) and the substitutions mentioned.
 
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