Propositional Logic Classical Propositional Logic 1.𝐴⊃(𝐵⊃𝐴) A⊃(B⊃A) A→(B→A)Introduction of an assumptionPL.FL.01axiom✹ 2.(𝐴⊃(𝐵⊃𝐶)) ⊃ ((𝐴⊃𝐵)⊃(𝐴⊃𝐶)) (A⊃(B⊃C)) ⊃ ((A⊃B)⊃(A⊃C)) (A→(B→C)) → ((A→B)→(A→C))PL.FL.02axiom✹ 3.(¬𝐴⊃¬𝐵) ⊃ (𝐵 ⊃ 𝐴) (¬A⊃¬B) ⊃ (B ⊃ A) (¬A→¬B) → (B → A)PL.FL.03axiom✹ Branches Classical logic Classical logic