Theorem nfimd 1898

Description: If in a context 𝑥 is not free in 𝜓 and 𝜒, then it is not free in (𝜓 → 𝜒). Deduction form of nfim 1900. (Contributed by Mario Carneiro, 24-Sep-2016.) (Proof shortened by Wolf Lammen, 30-Dec-2017.) df-nf 1788 changed. (Revised by Wolf Lammen, 18-Sep-2021.) Eliminate curried form of nfimt 1899. (Revised by Wolf Lammen, 10-Jul-2022.)

Hypotheses

Ref	Expression
nfimd.1	⊢ (𝜑 → Ⅎ𝑥𝜓)
nfimd.2	⊢ (𝜑 → Ⅎ𝑥𝜒)

Assertion

Ref	Expression
nfimd	⊢ (𝜑 → Ⅎ𝑥(𝜓 → 𝜒))

Proof of Theorem nfimd

Step	Hyp	Ref	Expression
1		19.35 1881	. . . 4 ⊢ (∃𝑥(𝜓 → 𝜒) ↔ (∀𝑥𝜓 → ∃𝑥𝜒))
2	1	biimpi 215	. . 3 ⊢ (∃𝑥(𝜓 → 𝜒) → (∀𝑥𝜓 → ∃𝑥𝜒))
3		nfimd.1	. . . . 5 ⊢ (𝜑 → Ⅎ𝑥𝜓)
4	3	nfrd 1795	. . . 4 ⊢ (𝜑 → (∃𝑥𝜓 → ∀𝑥𝜓))
5		nfimd.2	. . . . 5 ⊢ (𝜑 → Ⅎ𝑥𝜒)
6	5	nfrd 1795	. . . 4 ⊢ (𝜑 → (∃𝑥𝜒 → ∀𝑥𝜒))
7	4, 6	imim12d 81	. . 3 ⊢ (𝜑 → ((∀𝑥𝜓 → ∃𝑥𝜒) → (∃𝑥𝜓 → ∀𝑥𝜒)))
8		19.38 1842	. . 3 ⊢ ((∃𝑥𝜓 → ∀𝑥𝜒) → ∀𝑥(𝜓 → 𝜒))
9	2, 7, 8	syl56 36	. 2 ⊢ (𝜑 → (∃𝑥(𝜓 → 𝜒) → ∀𝑥(𝜓 → 𝜒)))
10	9	nfd 1794	1 ⊢ (𝜑 → Ⅎ𝑥(𝜓 → 𝜒))

Syntax hints:   → wi 4  ∀wal 1537  ∃wex 1783  Ⅎwnf 1787

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1799  ax-4 1813

This theorem depends on definitions:  df-bi 206  df-ex 1784  df-nf 1788

This theorem is referenced by:  nfimt  1899  nfand  1901  nfbid  1906  nfim1  2195  hbimd  2298  dvelimhw  2345  dvelimf  2448  nfmod2  2558  nfmodv  2559  nfabdw  2929  nfraldw  3146  nfraldwOLD  3147  nfrald  3148  nfifd  4485  nfixpw  8662  nfixp  8663  axrepndlem1  10279  axrepndlem2  10280  axunndlem1  10282  axunnd  10283  axpowndlem2  10285  axpowndlem3  10286  axpowndlem4  10287  axregndlem2  10290  axregnd  10291  axinfndlem1  10292  axinfnd  10293  axacndlem4  10297  axacndlem5  10298  axacnd  10299  bj-dvelimdv  34962  wl-mo2df  35652  wl-mo2t  35657  riotasv2d  36898  nfintd  46265