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Mirrors > Home > ILE Home > Th. List > mtbi | GIF version |
Description: An inference from a biconditional, related to modus tollens. (Contributed by NM, 15-Nov-1994.) (Proof shortened by Wolf Lammen, 25-Oct-2012.) |
Ref | Expression |
---|---|
mtbi.1 | ⊢ ¬ 𝜑 |
mtbi.2 | ⊢ (𝜑 ↔ 𝜓) |
Ref | Expression |
---|---|
mtbi | ⊢ ¬ 𝜓 |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | mtbi.1 | . 2 ⊢ ¬ 𝜑 | |
2 | mtbi.2 | . . 3 ⊢ (𝜑 ↔ 𝜓) | |
3 | 2 | biimpri 131 | . 2 ⊢ (𝜓 → 𝜑) |
4 | 1, 3 | mto 620 | 1 ⊢ ¬ 𝜓 |
Colors of variables: wff set class |
Syntax hints: ¬ wn 3 ↔ wb 103 |
This theorem was proved from axioms: ax-1 5 ax-2 6 ax-mp 7 ax-ia1 104 ax-ia2 105 ax-ia3 106 ax-in1 576 ax-in2 577 |
This theorem depends on definitions: df-bi 115 |
This theorem is referenced by: mtbir 628 vprc 3909 vnex 3911 onsucelsucexmid 4273 dtruex 4302 dmsn0 4808 php5 6344 ndvdsi 10333 nprmi 10506 bj-vprc 10687 bj-vnex 10689 |
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