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Mirrors > Home > MPE Home > Th. List > nd2 | Structured version Visualization version GIF version |
Description: A lemma for proving conditionless ZFC axioms. Usage of this theorem is discouraged because it depends on ax-13 2379. (Contributed by NM, 1-Jan-2002.) (New usage is discouraged.) |
Ref | Expression |
---|---|
nd2 | ⊢ (∀𝑥 𝑥 = 𝑦 → ¬ ∀𝑥 𝑧 ∈ 𝑦) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | elirrv 9044 | . . 3 ⊢ ¬ 𝑧 ∈ 𝑧 | |
2 | stdpc4 2073 | . . . 4 ⊢ (∀𝑦 𝑧 ∈ 𝑦 → [𝑧 / 𝑦]𝑧 ∈ 𝑦) | |
3 | 1 | nfnth 1804 | . . . . 5 ⊢ Ⅎ𝑦 𝑧 ∈ 𝑧 |
4 | elequ2 2126 | . . . . 5 ⊢ (𝑦 = 𝑧 → (𝑧 ∈ 𝑦 ↔ 𝑧 ∈ 𝑧)) | |
5 | 3, 4 | sbie 2521 | . . . 4 ⊢ ([𝑧 / 𝑦]𝑧 ∈ 𝑦 ↔ 𝑧 ∈ 𝑧) |
6 | 2, 5 | sylib 221 | . . 3 ⊢ (∀𝑦 𝑧 ∈ 𝑦 → 𝑧 ∈ 𝑧) |
7 | 1, 6 | mto 200 | . 2 ⊢ ¬ ∀𝑦 𝑧 ∈ 𝑦 |
8 | axc11 2441 | . 2 ⊢ (∀𝑥 𝑥 = 𝑦 → (∀𝑥 𝑧 ∈ 𝑦 → ∀𝑦 𝑧 ∈ 𝑦)) | |
9 | 7, 8 | mtoi 202 | 1 ⊢ (∀𝑥 𝑥 = 𝑦 → ¬ ∀𝑥 𝑧 ∈ 𝑦) |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 → wi 4 ∀wal 1536 [wsb 2069 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1797 ax-4 1811 ax-5 1911 ax-6 1970 ax-7 2015 ax-8 2113 ax-9 2121 ax-10 2142 ax-12 2175 ax-13 2379 ax-ext 2770 ax-sep 5167 ax-nul 5174 ax-pr 5295 ax-reg 9040 |
This theorem depends on definitions: df-bi 210 df-an 400 df-or 845 df-tru 1541 df-ex 1782 df-nf 1786 df-sb 2070 df-clab 2777 df-cleq 2791 df-clel 2870 df-ral 3111 df-rex 3112 df-v 3443 df-dif 3884 df-un 3886 df-nul 4244 df-sn 4526 df-pr 4528 |
This theorem is referenced by: axrepnd 10005 axpownd 10012 axinfndlem1 10016 axacndlem4 10021 |
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