Theorem cnv0 5869

Description: The converse of the empty set. (Contributed by NM, 6-Apr-1998.) Remove dependency on ax-sep 5256, ax-nul 5268, ax-pr 5404. (Revised by KP, 25-Oct-2021.) Avoid ax-12 2211. (Revised by TM, 31-Jan-2026.)

Assertion

Ref	Expression
cnv0	⊢ ◡∅ = ∅

Proof of Theorem cnv0

Dummy variables 𝑥 𝑦 𝑧 are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		br0 5159	. . . . . 6 ⊢ ¬ 𝑦∅𝑧
2	1	intnan 491	. . . . 5 ⊢ ¬ (𝑥 = ⟨𝑧, 𝑦⟩ ∧ 𝑦∅𝑧)
3	2	nex 1828	. . . 4 ⊢ ¬ ∃𝑦(𝑥 = ⟨𝑧, 𝑦⟩ ∧ 𝑦∅𝑧)
4	3	nex 1828	. . 3 ⊢ ¬ ∃𝑧∃𝑦(𝑥 = ⟨𝑧, 𝑦⟩ ∧ 𝑦∅𝑧)
5		df-cnv 5669	. . . . 5 ⊢ ◡∅ = {⟨𝑧, 𝑦⟩ ∣ 𝑦∅𝑧}
6	5	eleq2i 2853	. . . 4 ⊢ (𝑥 ∈ ◡∅ ↔ 𝑥 ∈ {⟨𝑧, 𝑦⟩ ∣ 𝑦∅𝑧})
7		elopabw 5510	. . . . 5 ⊢ (𝑥 ∈ V → (𝑥 ∈ {⟨𝑧, 𝑦⟩ ∣ 𝑦∅𝑧} ↔ ∃𝑧∃𝑦(𝑥 = ⟨𝑧, 𝑦⟩ ∧ 𝑦∅𝑧)))
8	7	elv 3458	. . . 4 ⊢ (𝑥 ∈ {⟨𝑧, 𝑦⟩ ∣ 𝑦∅𝑧} ↔ ∃𝑧∃𝑦(𝑥 = ⟨𝑧, 𝑦⟩ ∧ 𝑦∅𝑧))
9	6, 8	bitri 278	. . 3 ⊢ (𝑥 ∈ ◡∅ ↔ ∃𝑧∃𝑦(𝑥 = ⟨𝑧, 𝑦⟩ ∧ 𝑦∅𝑧))
10	4, 9	mtbir 326	. 2 ⊢ ¬ 𝑥 ∈ ◡∅
11	10	nel0 4308	1 ⊢ ◡∅ = ∅

Syntax hints:   ↔ wb 209   ∧ wa 400   = wceq 1568  ∃wex 1807   ∈ wcel 2141  Vcvv 3453  ∅c0 4285  ⟨cop 4594   class class class wbr 5108  {copab 5172  ^◡ccnv 5660

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1823  ax-4 1837  ax-5 1938  ax-6 1995  ax-7 2036  ax-8 2143  ax-9 2151  ax-ext 2733

This theorem depends on definitions:  df-bi 210  df-an 401  df-tru 1571  df-fal 1581  df-ex 1808  df-sb 2095  df-clab 2740  df-cleq 2753  df-clel 2836  df-v 3455  df-dif 3907  df-nul 4286  df-br 5109  df-opab 5173  df-cnv 5669

This theorem is referenced by:  csbcnv  5872  xp0OLD  6155  cnveq0  6196  co01  6263  funcnv0  6602  f1o00  6856  tpos0  8251  cnvfi  9159  oduleval  18344  ust0  24356  nghmfval  24858  isnghm  24859  1pthdlem1  30452  mptiffisupp  33004  tocycf  33403  tocyc01  33404  vieta  33936  mthmval  36021  resnonrel  44266  cononrel1  44268  cononrel2  44269  cnvrcl0  44299  0cnf  46539