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Mirrors > Home > MPE Home > Th. List > nfor | Structured version Visualization version GIF version |
Description: If 𝑥 is not free in 𝜑 and 𝜓, then it is not free in (𝜑 ∨ 𝜓). (Contributed by NM, 5-Aug-1993.) (Revised by Mario Carneiro, 11-Aug-2016.) |
Ref | Expression |
---|---|
nf.1 | ⊢ Ⅎ𝑥𝜑 |
nf.2 | ⊢ Ⅎ𝑥𝜓 |
Ref | Expression |
---|---|
nfor | ⊢ Ⅎ𝑥(𝜑 ∨ 𝜓) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | df-or 847 | . 2 ⊢ ((𝜑 ∨ 𝜓) ↔ (¬ 𝜑 → 𝜓)) | |
2 | nf.1 | . . . 4 ⊢ Ⅎ𝑥𝜑 | |
3 | 2 | nfn 1856 | . . 3 ⊢ Ⅎ𝑥 ¬ 𝜑 |
4 | nf.2 | . . 3 ⊢ Ⅎ𝑥𝜓 | |
5 | 3, 4 | nfim 1895 | . 2 ⊢ Ⅎ𝑥(¬ 𝜑 → 𝜓) |
6 | 1, 5 | nfxfr 1851 | 1 ⊢ Ⅎ𝑥(𝜑 ∨ 𝜓) |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 → wi 4 ∨ wo 846 Ⅎwnf 1781 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1793 ax-4 1807 |
This theorem depends on definitions: df-bi 207 df-an 396 df-or 847 df-ex 1778 df-nf 1782 |
This theorem is referenced by: nf3or 1904 axi12 2709 axbnd 2710 nfun 4193 nfunOLD 4194 nfpr 4715 rabsnifsb 4747 disjxun 5164 fsuppmapnn0fiubex 14043 nfsum1 15738 nfsum 15739 nfcprod1 15956 nfcprod 15957 fdc1 37706 dvdsrabdioph 42766 mnringmulrcld 44197 disjinfi 45099 iundjiun 46381 |
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