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Theorem 0vconngr 27976
Description: A graph without vertices is connected. (Contributed by Alexander van der Vekens, 2-Dec-2017.) (Revised by AV, 15-Feb-2021.)
Assertion
Ref Expression
0vconngr ((𝐺𝑊 ∧ (Vtx‘𝐺) = ∅) → 𝐺 ∈ ConnGraph)

Proof of Theorem 0vconngr
Dummy variables 𝑓 𝑘 𝑛 𝑝 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 rzal 4425 . . 3 ((Vtx‘𝐺) = ∅ → ∀𝑘 ∈ (Vtx‘𝐺)∀𝑛 ∈ (Vtx‘𝐺)∃𝑓𝑝 𝑓(𝑘(PathsOn‘𝐺)𝑛)𝑝)
21adantl 485 . 2 ((𝐺𝑊 ∧ (Vtx‘𝐺) = ∅) → ∀𝑘 ∈ (Vtx‘𝐺)∀𝑛 ∈ (Vtx‘𝐺)∃𝑓𝑝 𝑓(𝑘(PathsOn‘𝐺)𝑛)𝑝)
3 eqid 2822 . . . 4 (Vtx‘𝐺) = (Vtx‘𝐺)
43isconngr 27972 . . 3 (𝐺𝑊 → (𝐺 ∈ ConnGraph ↔ ∀𝑘 ∈ (Vtx‘𝐺)∀𝑛 ∈ (Vtx‘𝐺)∃𝑓𝑝 𝑓(𝑘(PathsOn‘𝐺)𝑛)𝑝))
54adantr 484 . 2 ((𝐺𝑊 ∧ (Vtx‘𝐺) = ∅) → (𝐺 ∈ ConnGraph ↔ ∀𝑘 ∈ (Vtx‘𝐺)∀𝑛 ∈ (Vtx‘𝐺)∃𝑓𝑝 𝑓(𝑘(PathsOn‘𝐺)𝑛)𝑝))
62, 5mpbird 260 1 ((𝐺𝑊 ∧ (Vtx‘𝐺) = ∅) → 𝐺 ∈ ConnGraph)
Colors of variables: wff setvar class
Syntax hints:  wi 4  wb 209  wa 399   = wceq 1538  wex 1781  wcel 2114  wral 3130  c0 4265   class class class wbr 5042  cfv 6334  (class class class)co 7140  Vtxcvtx 26787  PathsOncpthson 27501  ConnGraphcconngr 27969
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 2116  ax-9 2124  ax-10 2145  ax-11 2161  ax-12 2178  ax-ext 2794  ax-nul 5186
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 2622  df-eu 2653  df-clab 2801  df-cleq 2815  df-clel 2894  df-nfc 2962  df-ne 3012  df-ral 3135  df-rex 3136  df-v 3471  df-sbc 3748  df-dif 3911  df-un 3913  df-in 3915  df-ss 3925  df-nul 4266  df-sn 4540  df-pr 4542  df-op 4546  df-uni 4814  df-br 5043  df-iota 6293  df-fv 6342  df-ov 7143  df-conngr 27970
This theorem is referenced by:  1conngr  27977
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