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Related theorems GIF version |
| Description: Inference that swaps (commutes) antecedents in an implication. |
| Ref | Expression |
|---|---|
| comm.1 | ⊢ (φ → (ψ → χ)) |
| Ref | Expression |
|---|---|
| com12 | ⊢ (ψ → (φ → χ)) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | ax-1 3 | . 2 ⊢ (ψ → (φ → ψ)) | |
| 2 | comm.1 | . . 3 ⊢ (φ → (ψ → χ)) | |
| 3 | 2 | a2i 8 | . 2 ⊢ ((φ → ψ) → (φ → χ)) |
| 4 | 1, 3 | syl 12 | 1 ⊢ (ψ → (φ → χ)) |