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| Description: Deduction version of nfreu 3434. Usage of this theorem is discouraged because it depends on ax-13 2376. (Contributed by NM, 15-Feb-2013.) (Revised by Mario Carneiro, 8-Oct-2016.) (New usage is discouraged.) | 
| Ref | Expression | 
|---|---|
| nfrmod.1 | ⊢ Ⅎ𝑦𝜑 | 
| nfrmod.2 | ⊢ (𝜑 → Ⅎ𝑥𝐴) | 
| nfrmod.3 | ⊢ (𝜑 → Ⅎ𝑥𝜓) | 
| Ref | Expression | 
|---|---|
| nfreud | ⊢ (𝜑 → Ⅎ𝑥∃!𝑦 ∈ 𝐴 𝜓) | 
| Step | Hyp | Ref | Expression | 
|---|---|---|---|
| 1 | df-reu 3380 | . 2 ⊢ (∃!𝑦 ∈ 𝐴 𝜓 ↔ ∃!𝑦(𝑦 ∈ 𝐴 ∧ 𝜓)) | |
| 2 | nfrmod.1 | . . 3 ⊢ Ⅎ𝑦𝜑 | |
| 3 | nfcvf 2931 | . . . . . 6 ⊢ (¬ ∀𝑥 𝑥 = 𝑦 → Ⅎ𝑥𝑦) | |
| 4 | 3 | adantl 481 | . . . . 5 ⊢ ((𝜑 ∧ ¬ ∀𝑥 𝑥 = 𝑦) → Ⅎ𝑥𝑦) | 
| 5 | nfrmod.2 | . . . . . 6 ⊢ (𝜑 → Ⅎ𝑥𝐴) | |
| 6 | 5 | adantr 480 | . . . . 5 ⊢ ((𝜑 ∧ ¬ ∀𝑥 𝑥 = 𝑦) → Ⅎ𝑥𝐴) | 
| 7 | 4, 6 | nfeld 2916 | . . . 4 ⊢ ((𝜑 ∧ ¬ ∀𝑥 𝑥 = 𝑦) → Ⅎ𝑥 𝑦 ∈ 𝐴) | 
| 8 | nfrmod.3 | . . . . 5 ⊢ (𝜑 → Ⅎ𝑥𝜓) | |
| 9 | 8 | adantr 480 | . . . 4 ⊢ ((𝜑 ∧ ¬ ∀𝑥 𝑥 = 𝑦) → Ⅎ𝑥𝜓) | 
| 10 | 7, 9 | nfand 1896 | . . 3 ⊢ ((𝜑 ∧ ¬ ∀𝑥 𝑥 = 𝑦) → Ⅎ𝑥(𝑦 ∈ 𝐴 ∧ 𝜓)) | 
| 11 | 2, 10 | nfeud2 2589 | . 2 ⊢ (𝜑 → Ⅎ𝑥∃!𝑦(𝑦 ∈ 𝐴 ∧ 𝜓)) | 
| 12 | 1, 11 | nfxfrd 1853 | 1 ⊢ (𝜑 → Ⅎ𝑥∃!𝑦 ∈ 𝐴 𝜓) | 
| Colors of variables: wff setvar class | 
| Syntax hints: ¬ wn 3 → wi 4 ∧ wa 395 ∀wal 1537 Ⅎwnf 1782 ∈ wcel 2107 ∃!weu 2567 Ⅎwnfc 2889 ∃!wreu 3377 | 
| This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1794 ax-4 1808 ax-5 1909 ax-6 1966 ax-7 2006 ax-8 2109 ax-9 2117 ax-10 2140 ax-11 2156 ax-12 2176 ax-13 2376 ax-ext 2707 | 
| This theorem depends on definitions: df-bi 207 df-an 396 df-or 848 df-tru 1542 df-ex 1779 df-nf 1783 df-mo 2539 df-eu 2568 df-cleq 2728 df-clel 2815 df-nfc 2891 df-reu 3380 | 
| This theorem is referenced by: nfreu 3434 | 
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