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Theorem umgr0e 26910
 Description: The empty graph, with vertices but no edges, is a multigraph. (Contributed by Mario Carneiro, 12-Mar-2015.) (Revised by AV, 25-Nov-2020.)
Hypotheses
Ref Expression
umgr0e.g (𝜑𝐺𝑊)
umgr0e.e (𝜑 → (iEdg‘𝐺) = ∅)
Assertion
Ref Expression
umgr0e (𝜑𝐺 ∈ UMGraph)

Proof of Theorem umgr0e
Dummy variable 𝑥 is distinct from all other variables.
StepHypRef Expression
1 umgr0e.e . . . 4 (𝜑 → (iEdg‘𝐺) = ∅)
21f10d 6623 . . 3 (𝜑 → (iEdg‘𝐺):dom (iEdg‘𝐺)–1-1→{𝑥 ∈ (𝒫 (Vtx‘𝐺) ∖ {∅}) ∣ (♯‘𝑥) = 2})
3 f1f 6549 . . 3 ((iEdg‘𝐺):dom (iEdg‘𝐺)–1-1→{𝑥 ∈ (𝒫 (Vtx‘𝐺) ∖ {∅}) ∣ (♯‘𝑥) = 2} → (iEdg‘𝐺):dom (iEdg‘𝐺)⟶{𝑥 ∈ (𝒫 (Vtx‘𝐺) ∖ {∅}) ∣ (♯‘𝑥) = 2})
42, 3syl 17 . 2 (𝜑 → (iEdg‘𝐺):dom (iEdg‘𝐺)⟶{𝑥 ∈ (𝒫 (Vtx‘𝐺) ∖ {∅}) ∣ (♯‘𝑥) = 2})
5 umgr0e.g . . 3 (𝜑𝐺𝑊)
6 eqid 2798 . . . 4 (Vtx‘𝐺) = (Vtx‘𝐺)
7 eqid 2798 . . . 4 (iEdg‘𝐺) = (iEdg‘𝐺)
86, 7isumgr 26895 . . 3 (𝐺𝑊 → (𝐺 ∈ UMGraph ↔ (iEdg‘𝐺):dom (iEdg‘𝐺)⟶{𝑥 ∈ (𝒫 (Vtx‘𝐺) ∖ {∅}) ∣ (♯‘𝑥) = 2}))
95, 8syl 17 . 2 (𝜑 → (𝐺 ∈ UMGraph ↔ (iEdg‘𝐺):dom (iEdg‘𝐺)⟶{𝑥 ∈ (𝒫 (Vtx‘𝐺) ∖ {∅}) ∣ (♯‘𝑥) = 2}))
104, 9mpbird 260 1 (𝜑𝐺 ∈ UMGraph)
 Colors of variables: wff setvar class Syntax hints:   → wi 4   ↔ wb 209   = wceq 1538   ∈ wcel 2111  {crab 3110   ∖ cdif 3878  ∅c0 4243  𝒫 cpw 4497  {csn 4525  dom cdm 5519  ⟶wf 6320  –1-1→wf1 6321  ‘cfv 6324  2c2 11682  ♯chash 13688  Vtxcvtx 26796  iEdgciedg 26797  UMGraphcumgr 26881 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-11 2158  ax-12 2175  ax-ext 2770  ax-sep 5167  ax-nul 5174  ax-pr 5295 This theorem depends on definitions:  df-bi 210  df-an 400  df-or 845  df-3an 1086  df-tru 1541  df-ex 1782  df-nf 1786  df-sb 2070  df-mo 2598  df-eu 2629  df-clab 2777  df-cleq 2791  df-clel 2870  df-nfc 2938  df-ral 3111  df-rex 3112  df-rab 3115  df-v 3443  df-sbc 3721  df-dif 3884  df-un 3886  df-in 3888  df-ss 3898  df-nul 4244  df-if 4426  df-pw 4499  df-sn 4526  df-pr 4528  df-op 4532  df-uni 4801  df-br 5031  df-opab 5093  df-id 5425  df-xp 5525  df-rel 5526  df-cnv 5527  df-co 5528  df-dm 5529  df-rn 5530  df-iota 6283  df-fun 6326  df-fn 6327  df-f 6328  df-f1 6329  df-fv 6332  df-umgr 26883 This theorem is referenced by:  upgr0e  26911
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