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Mirrors > Home > MPE Home > Th. List > mtand | Structured version Visualization version GIF version |
Description: A modus tollens deduction. (Contributed by Jeff Hankins, 19-Aug-2009.) |
Ref | Expression |
---|---|
mtand.1 | ⊢ (𝜑 → ¬ 𝜒) |
mtand.2 | ⊢ ((𝜑 ∧ 𝜓) → 𝜒) |
Ref | Expression |
---|---|
mtand | ⊢ (𝜑 → ¬ 𝜓) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | mtand.1 | . 2 ⊢ (𝜑 → ¬ 𝜒) | |
2 | mtand.2 | . . 3 ⊢ ((𝜑 ∧ 𝜓) → 𝜒) | |
3 | 2 | ex 412 | . 2 ⊢ (𝜑 → (𝜓 → 𝜒)) |
4 | 1, 3 | mtod 197 | 1 ⊢ (𝜑 → ¬ 𝜓) |
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