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Mirrors > Home > MPE Home > Th. List > eulerpath | Structured version Visualization version GIF version |
Description: A pseudograph with an Eulerian path has either zero or two vertices of odd degree. (Contributed by Mario Carneiro, 7-Apr-2015.) (Revised by AV, 26-Feb-2021.) |
Ref | Expression |
---|---|
eulerpathpr.v | ⊢ 𝑉 = (Vtx‘𝐺) |
Ref | Expression |
---|---|
eulerpath | ⊢ ((𝐺 ∈ UPGraph ∧ (EulerPaths‘𝐺) ≠ ∅) → (♯‘{𝑥 ∈ 𝑉 ∣ ¬ 2 ∥ ((VtxDeg‘𝐺)‘𝑥)}) ∈ {0, 2}) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | releupth 27731 | . . . . . 6 ⊢ Rel (EulerPaths‘𝐺) | |
2 | reldm0 5642 | . . . . . 6 ⊢ (Rel (EulerPaths‘𝐺) → ((EulerPaths‘𝐺) = ∅ ↔ dom (EulerPaths‘𝐺) = ∅)) | |
3 | 1, 2 | ax-mp 5 | . . . . 5 ⊢ ((EulerPaths‘𝐺) = ∅ ↔ dom (EulerPaths‘𝐺) = ∅) |
4 | 3 | necon3bii 3019 | . . . 4 ⊢ ((EulerPaths‘𝐺) ≠ ∅ ↔ dom (EulerPaths‘𝐺) ≠ ∅) |
5 | n0 4198 | . . . 4 ⊢ (dom (EulerPaths‘𝐺) ≠ ∅ ↔ ∃𝑓 𝑓 ∈ dom (EulerPaths‘𝐺)) | |
6 | 4, 5 | bitri 267 | . . 3 ⊢ ((EulerPaths‘𝐺) ≠ ∅ ↔ ∃𝑓 𝑓 ∈ dom (EulerPaths‘𝐺)) |
7 | vex 3418 | . . . . . 6 ⊢ 𝑓 ∈ V | |
8 | 7 | eldm 5620 | . . . . 5 ⊢ (𝑓 ∈ dom (EulerPaths‘𝐺) ↔ ∃𝑝 𝑓(EulerPaths‘𝐺)𝑝) |
9 | eulerpathpr.v | . . . . . . . 8 ⊢ 𝑉 = (Vtx‘𝐺) | |
10 | 9 | eulerpathpr 27773 | . . . . . . 7 ⊢ ((𝐺 ∈ UPGraph ∧ 𝑓(EulerPaths‘𝐺)𝑝) → (♯‘{𝑥 ∈ 𝑉 ∣ ¬ 2 ∥ ((VtxDeg‘𝐺)‘𝑥)}) ∈ {0, 2}) |
11 | 10 | expcom 406 | . . . . . 6 ⊢ (𝑓(EulerPaths‘𝐺)𝑝 → (𝐺 ∈ UPGraph → (♯‘{𝑥 ∈ 𝑉 ∣ ¬ 2 ∥ ((VtxDeg‘𝐺)‘𝑥)}) ∈ {0, 2})) |
12 | 11 | exlimiv 1889 | . . . . 5 ⊢ (∃𝑝 𝑓(EulerPaths‘𝐺)𝑝 → (𝐺 ∈ UPGraph → (♯‘{𝑥 ∈ 𝑉 ∣ ¬ 2 ∥ ((VtxDeg‘𝐺)‘𝑥)}) ∈ {0, 2})) |
13 | 8, 12 | sylbi 209 | . . . 4 ⊢ (𝑓 ∈ dom (EulerPaths‘𝐺) → (𝐺 ∈ UPGraph → (♯‘{𝑥 ∈ 𝑉 ∣ ¬ 2 ∥ ((VtxDeg‘𝐺)‘𝑥)}) ∈ {0, 2})) |
14 | 13 | exlimiv 1889 | . . 3 ⊢ (∃𝑓 𝑓 ∈ dom (EulerPaths‘𝐺) → (𝐺 ∈ UPGraph → (♯‘{𝑥 ∈ 𝑉 ∣ ¬ 2 ∥ ((VtxDeg‘𝐺)‘𝑥)}) ∈ {0, 2})) |
15 | 6, 14 | sylbi 209 | . 2 ⊢ ((EulerPaths‘𝐺) ≠ ∅ → (𝐺 ∈ UPGraph → (♯‘{𝑥 ∈ 𝑉 ∣ ¬ 2 ∥ ((VtxDeg‘𝐺)‘𝑥)}) ∈ {0, 2})) |
16 | 15 | impcom 399 | 1 ⊢ ((𝐺 ∈ UPGraph ∧ (EulerPaths‘𝐺) ≠ ∅) → (♯‘{𝑥 ∈ 𝑉 ∣ ¬ 2 ∥ ((VtxDeg‘𝐺)‘𝑥)}) ∈ {0, 2}) |
Colors of variables: wff setvar class |
Syntax hints: ¬ wn 3 → wi 4 ↔ wb 198 ∧ wa 387 = wceq 1507 ∃wex 1742 ∈ wcel 2050 ≠ wne 2967 {crab 3092 ∅c0 4180 {cpr 4444 class class class wbr 4930 dom cdm 5408 Rel wrel 5413 ‘cfv 6190 0cc0 10337 2c2 11498 ♯chash 13508 ∥ cdvds 15470 Vtxcvtx 26487 UPGraphcupgr 26571 VtxDegcvtxdg 26953 EulerPathsceupth 27729 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1758 ax-4 1772 ax-5 1869 ax-6 1928 ax-7 1965 ax-8 2052 ax-9 2059 ax-10 2079 ax-11 2093 ax-12 2106 ax-13 2301 ax-ext 2750 ax-rep 5050 ax-sep 5061 ax-nul 5068 ax-pow 5120 ax-pr 5187 ax-un 7281 ax-cnex 10393 ax-resscn 10394 ax-1cn 10395 ax-icn 10396 ax-addcl 10397 ax-addrcl 10398 ax-mulcl 10399 ax-mulrcl 10400 ax-mulcom 10401 ax-addass 10402 ax-mulass 10403 ax-distr 10404 ax-i2m1 10405 ax-1ne0 10406 ax-1rid 10407 ax-rnegex 10408 ax-rrecex 10409 ax-cnre 10410 ax-pre-lttri 10411 ax-pre-lttrn 10412 ax-pre-ltadd 10413 ax-pre-mulgt0 10414 ax-pre-sup 10415 |
This theorem depends on definitions: df-bi 199 df-an 388 df-or 834 df-ifp 1044 df-3or 1069 df-3an 1070 df-tru 1510 df-ex 1743 df-nf 1747 df-sb 2016 df-mo 2547 df-eu 2583 df-clab 2759 df-cleq 2771 df-clel 2846 df-nfc 2918 df-ne 2968 df-nel 3074 df-ral 3093 df-rex 3094 df-reu 3095 df-rmo 3096 df-rab 3097 df-v 3417 df-sbc 3684 df-csb 3789 df-dif 3834 df-un 3836 df-in 3838 df-ss 3845 df-pss 3847 df-nul 4181 df-if 4352 df-pw 4425 df-sn 4443 df-pr 4445 df-tp 4447 df-op 4449 df-uni 4714 df-int 4751 df-iun 4795 df-br 4931 df-opab 4993 df-mpt 5010 df-tr 5032 df-id 5313 df-eprel 5318 df-po 5327 df-so 5328 df-fr 5367 df-we 5369 df-xp 5414 df-rel 5415 df-cnv 5416 df-co 5417 df-dm 5418 df-rn 5419 df-res 5420 df-ima 5421 df-pred 5988 df-ord 6034 df-on 6035 df-lim 6036 df-suc 6037 df-iota 6154 df-fun 6192 df-fn 6193 df-f 6194 df-f1 6195 df-fo 6196 df-f1o 6197 df-fv 6198 df-riota 6939 df-ov 6981 df-oprab 6982 df-mpo 6983 df-om 7399 df-1st 7503 df-2nd 7504 df-wrecs 7752 df-recs 7814 df-rdg 7852 df-1o 7907 df-2o 7908 df-oadd 7911 df-er 8091 df-map 8210 df-pm 8211 df-en 8309 df-dom 8310 df-sdom 8311 df-fin 8312 df-sup 8703 df-inf 8704 df-dju 9126 df-card 9164 df-pnf 10478 df-mnf 10479 df-xr 10480 df-ltxr 10481 df-le 10482 df-sub 10674 df-neg 10675 df-div 11101 df-nn 11442 df-2 11506 df-3 11507 df-n0 11711 df-xnn0 11783 df-z 11797 df-uz 12062 df-rp 12208 df-xadd 12328 df-fz 12712 df-fzo 12853 df-seq 13188 df-exp 13248 df-hash 13509 df-word 13676 df-cj 14322 df-re 14323 df-im 14324 df-sqrt 14458 df-abs 14459 df-dvds 15471 df-vtx 26489 df-iedg 26490 df-edg 26539 df-uhgr 26549 df-ushgr 26550 df-upgr 26573 df-uspgr 26641 df-vtxdg 26954 df-wlks 27087 df-trls 27183 df-eupth 27730 |
This theorem is referenced by: konigsberg 27792 |
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