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Mirrors > Home > MPE Home > Th. List > abfOLD | Structured version Visualization version GIF version |
Description: Obsolete version of abf 4292 as of 28-Jun-2024. (Contributed by NM, 20-Jan-2012.) (Proof modification is discouraged.) (New usage is discouraged.) |
Ref | Expression |
---|---|
abfOLD.1 | ⊢ ¬ 𝜑 |
Ref | Expression |
---|---|
abfOLD | ⊢ {𝑥 ∣ 𝜑} = ∅ |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ab0 4266 | . 2 ⊢ ({𝑥 ∣ 𝜑} = ∅ ↔ ∀𝑥 ¬ 𝜑) | |
2 | abfOLD.1 | . 2 ⊢ ¬ 𝜑 | |
3 | 1, 2 | mpgbir 1802 | 1 ⊢ {𝑥 ∣ 𝜑} = ∅ |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 = wceq 1539 {cab 2736 ∅c0 4221 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1798 ax-4 1812 ax-5 1912 ax-6 1971 ax-7 2016 ax-9 2122 ax-10 2143 ax-11 2159 ax-12 2176 ax-ext 2730 |
This theorem depends on definitions: df-bi 210 df-an 401 df-or 846 df-tru 1542 df-fal 1552 df-ex 1783 df-nf 1787 df-sb 2071 df-clab 2737 df-cleq 2751 df-dif 3857 df-nul 4222 |
This theorem is referenced by: (None) |
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