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Theorem 0vconngr 27374
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 4215 . . 3 ((Vtx‘𝐺) = ∅ → ∀𝑘 ∈ (Vtx‘𝐺)∀𝑛 ∈ (Vtx‘𝐺)∃𝑓𝑝 𝑓(𝑘(PathsOn‘𝐺)𝑛)𝑝)
21adantl 467 . 2 ((𝐺𝑊 ∧ (Vtx‘𝐺) = ∅) → ∀𝑘 ∈ (Vtx‘𝐺)∀𝑛 ∈ (Vtx‘𝐺)∃𝑓𝑝 𝑓(𝑘(PathsOn‘𝐺)𝑛)𝑝)
3 eqid 2771 . . . 4 (Vtx‘𝐺) = (Vtx‘𝐺)
43isconngr 27370 . . 3 (𝐺𝑊 → (𝐺 ∈ ConnGraph ↔ ∀𝑘 ∈ (Vtx‘𝐺)∀𝑛 ∈ (Vtx‘𝐺)∃𝑓𝑝 𝑓(𝑘(PathsOn‘𝐺)𝑛)𝑝))
54adantr 466 . 2 ((𝐺𝑊 ∧ (Vtx‘𝐺) = ∅) → (𝐺 ∈ ConnGraph ↔ ∀𝑘 ∈ (Vtx‘𝐺)∀𝑛 ∈ (Vtx‘𝐺)∃𝑓𝑝 𝑓(𝑘(PathsOn‘𝐺)𝑛)𝑝))
62, 5mpbird 247 1 ((𝐺𝑊 ∧ (Vtx‘𝐺) = ∅) → 𝐺 ∈ ConnGraph)
Colors of variables: wff setvar class
Syntax hints:  wi 4  wb 196  wa 382   = wceq 1631  wex 1852  wcel 2145  wral 3061  c0 4064   class class class wbr 4787  cfv 6032  (class class class)co 6794  Vtxcvtx 26096  PathsOncpthson 26846  ConnGraphcconngr 27367
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1870  ax-4 1885  ax-5 1991  ax-6 2057  ax-7 2093  ax-9 2154  ax-10 2174  ax-11 2190  ax-12 2203  ax-13 2408  ax-ext 2751  ax-nul 4924
This theorem depends on definitions:  df-bi 197  df-an 383  df-or 829  df-3an 1073  df-tru 1634  df-ex 1853  df-nf 1858  df-sb 2050  df-eu 2622  df-clab 2758  df-cleq 2764  df-clel 2767  df-nfc 2902  df-ne 2944  df-ral 3066  df-rex 3067  df-rab 3070  df-v 3353  df-sbc 3589  df-dif 3727  df-un 3729  df-in 3731  df-ss 3738  df-nul 4065  df-if 4227  df-sn 4318  df-pr 4320  df-op 4324  df-uni 4576  df-br 4788  df-iota 5995  df-fv 6040  df-ov 6797  df-conngr 27368
This theorem is referenced by:  1conngr  27375
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