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Related theorems GIF version |
| Description: Syllogism deduction. (The proof was shortened by Mel L. O'Cat, 7-Aug-04.) |
| Ref | Expression |
|---|---|
| syld.1 | ⊢ (φ → (ψ → χ)) |
| syld.2 | ⊢ (φ → (χ → θ)) |
| Ref | Expression |
|---|---|
| syld | ⊢ (φ → (ψ → θ)) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | syld.1 | . 2 ⊢ (φ → (ψ → χ)) | |
| 2 | syld.2 | . . . 4 ⊢ (φ → (χ → θ)) | |
| 3 | 2 | syl3d 26 | . . 3 ⊢ (φ → ((ψ → χ) → (ψ → θ))) |
| 4 | 3 | a2i 8 | . 2 ⊢ ((φ → (ψ → χ)) → (φ → (ψ → θ))) |
| 5 | 1, 4 | ax-mp 6 | 1 ⊢ (φ → (ψ → θ)) |