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Mirrors > Home > MPE Home > Th. List > nfnf1 | Structured version Visualization version GIF version |
Description: The setvar 𝑥 is not free in Ⅎ𝑥𝜑. (Contributed by Mario Carneiro, 11-Aug-2016.) Remove dependency on ax-12 2177. (Revised by Wolf Lammen, 12-Oct-2021.) |
Ref | Expression |
---|---|
nfnf1 | ⊢ Ⅎ𝑥Ⅎ𝑥𝜑 |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | df-nf 1785 | . 2 ⊢ (Ⅎ𝑥𝜑 ↔ (∃𝑥𝜑 → ∀𝑥𝜑)) | |
2 | nfe1 2154 | . . 3 ⊢ Ⅎ𝑥∃𝑥𝜑 | |
3 | nfa1 2155 | . . 3 ⊢ Ⅎ𝑥∀𝑥𝜑 | |
4 | 2, 3 | nfim 1897 | . 2 ⊢ Ⅎ𝑥(∃𝑥𝜑 → ∀𝑥𝜑) |
5 | 1, 4 | nfxfr 1853 | 1 ⊢ Ⅎ𝑥Ⅎ𝑥𝜑 |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ∀wal 1535 ∃wex 1780 Ⅎwnf 1784 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1796 ax-4 1810 ax-10 2145 |
This theorem depends on definitions: df-bi 209 df-an 399 df-or 844 df-ex 1781 df-nf 1785 |
This theorem is referenced by: sb4bOLD 2500 nfsb4t 2539 nfsb4tALT 2604 nfnfc1 2980 nfabdw 3000 sbcnestgfw 4370 sbcnestgf 4375 bj-sbf4 34163 wl-equsal1t 34796 wl-sb6rft 34799 wl-sb8t 34803 wl-mo2tf 34822 wl-eutf 34824 wl-mo2t 34826 wl-mo3t 34827 wl-sb8eut 34828 ichnfim 43644 |
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