Theorem wlk2v2e 27017

Description: In a graph with two vertices and one edge connecting these two vertices, to go from one vertex to the other and back to the first vertex via the same/only edge is a walk. Notice that 𝐺 is a simple graph (without loops) only if 𝑋 ≠ 𝑌. (Contributed by Alexander van der Vekens, 22-Oct-2017.) (Revised by AV, 8-Jan-2021.)

Hypotheses

Ref	Expression
wlk2v2e.i	⊢ 𝐼 = ⟨“{𝑋, 𝑌}”⟩
wlk2v2e.f	⊢ 𝐹 = ⟨“00”⟩
wlk2v2e.x	⊢ 𝑋 ∈ V
wlk2v2e.y	⊢ 𝑌 ∈ V
wlk2v2e.p	⊢ 𝑃 = ⟨“𝑋𝑌𝑋”⟩
wlk2v2e.g	⊢ 𝐺 = ⟨{𝑋, 𝑌}, 𝐼⟩

Assertion

Ref	Expression
wlk2v2e	⊢ 𝐹(Walks‘𝐺)𝑃

Proof of Theorem wlk2v2e

Dummy variable 𝑘 is distinct from all other variables.

Step	Hyp	Ref	Expression
1		wlk2v2e.g	. . . . 5 ⊢ 𝐺 = ⟨{𝑋, 𝑌}, 𝐼⟩
2		wlk2v2e.i	. . . . . 6 ⊢ 𝐼 = ⟨“{𝑋, 𝑌}”⟩
3	2	opeq2i 4406	. . . . 5 ⊢ ⟨{𝑋, 𝑌}, 𝐼⟩ = ⟨{𝑋, 𝑌}, ⟨“{𝑋, 𝑌}”⟩⟩
4	1, 3	eqtri 2644	. . . 4 ⊢ 𝐺 = ⟨{𝑋, 𝑌}, ⟨“{𝑋, 𝑌}”⟩⟩
5		wlk2v2e.x	. . . . 5 ⊢ 𝑋 ∈ V
6		wlk2v2e.y	. . . . 5 ⊢ 𝑌 ∈ V
7		uspgr2v1e2w 26143	. . . . 5 ⊢ ((𝑋 ∈ V ∧ 𝑌 ∈ V) → ⟨{𝑋, 𝑌}, ⟨“{𝑋, 𝑌}”⟩⟩ ∈ USPGraph )
8	5, 6, 7	mp2an 708	. . . 4 ⊢ ⟨{𝑋, 𝑌}, ⟨“{𝑋, 𝑌}”⟩⟩ ∈ USPGraph
9	4, 8	eqeltri 2697	. . 3 ⊢ 𝐺 ∈ USPGraph
10		uspgrupgr 26071	. . 3 ⊢ (𝐺 ∈ USPGraph → 𝐺 ∈ UPGraph )
11	9, 10	ax-mp 5	. 2 ⊢ 𝐺 ∈ UPGraph
12		wlk2v2e.f	. . . . 5 ⊢ 𝐹 = ⟨“00”⟩
13	2, 12	wlk2v2elem1 27015	. . . 4 ⊢ 𝐹 ∈ Word dom 𝐼
14		wlk2v2e.p	. . . . . . . 8 ⊢ 𝑃 = ⟨“𝑋𝑌𝑋”⟩
15	5	prid1 4297	. . . . . . . . 9 ⊢ 𝑋 ∈ {𝑋, 𝑌}
16	6	prid2 4298	. . . . . . . . 9 ⊢ 𝑌 ∈ {𝑋, 𝑌}
17		s3cl 13624	. . . . . . . . 9 ⊢ ((𝑋 ∈ {𝑋, 𝑌} ∧ 𝑌 ∈ {𝑋, 𝑌} ∧ 𝑋 ∈ {𝑋, 𝑌}) → ⟨“𝑋𝑌𝑋”⟩ ∈ Word {𝑋, 𝑌})
18	15, 16, 15, 17	mp3an 1424	. . . . . . . 8 ⊢ ⟨“𝑋𝑌𝑋”⟩ ∈ Word {𝑋, 𝑌}
19	14, 18	eqeltri 2697	. . . . . . 7 ⊢ 𝑃 ∈ Word {𝑋, 𝑌}
20		wrdf 13310	. . . . . . 7 ⊢ (𝑃 ∈ Word {𝑋, 𝑌} → 𝑃:(0..^(#‘𝑃))⟶{𝑋, 𝑌})
21	19, 20	ax-mp 5	. . . . . 6 ⊢ 𝑃:(0..^(#‘𝑃))⟶{𝑋, 𝑌}
22	14	fveq2i 6194	. . . . . . . . 9 ⊢ (#‘𝑃) = (#‘⟨“𝑋𝑌𝑋”⟩)
23		s3len 13639	. . . . . . . . 9 ⊢ (#‘⟨“𝑋𝑌𝑋”⟩) = 3
24	22, 23	eqtr2i 2645	. . . . . . . 8 ⊢ 3 = (#‘𝑃)
25	24	oveq2i 6661	. . . . . . 7 ⊢ (0..^3) = (0..^(#‘𝑃))
26	25	feq2i 6037	. . . . . 6 ⊢ (𝑃:(0..^3)⟶{𝑋, 𝑌} ↔ 𝑃:(0..^(#‘𝑃))⟶{𝑋, 𝑌})
27	21, 26	mpbir 221	. . . . 5 ⊢ 𝑃:(0..^3)⟶{𝑋, 𝑌}
28	12	fveq2i 6194	. . . . . . . . 9 ⊢ (#‘𝐹) = (#‘⟨“00”⟩)
29		s2len 13634	. . . . . . . . 9 ⊢ (#‘⟨“00”⟩) = 2
30	28, 29	eqtri 2644	. . . . . . . 8 ⊢ (#‘𝐹) = 2
31	30	oveq2i 6661	. . . . . . 7 ⊢ (0...(#‘𝐹)) = (0...2)
32		3z 11410	. . . . . . . . 9 ⊢ 3 ∈ ℤ
33		fzoval 12471	. . . . . . . . 9 ⊢ (3 ∈ ℤ → (0..^3) = (0...(3 − 1)))
34	32, 33	ax-mp 5	. . . . . . . 8 ⊢ (0..^3) = (0...(3 − 1))
35		3m1e2 11137	. . . . . . . . 9 ⊢ (3 − 1) = 2
36	35	oveq2i 6661	. . . . . . . 8 ⊢ (0...(3 − 1)) = (0...2)
37	34, 36	eqtr2i 2645	. . . . . . 7 ⊢ (0...2) = (0..^3)
38	31, 37	eqtri 2644	. . . . . 6 ⊢ (0...(#‘𝐹)) = (0..^3)
39	38	feq2i 6037	. . . . 5 ⊢ (𝑃:(0...(#‘𝐹))⟶{𝑋, 𝑌} ↔ 𝑃:(0..^3)⟶{𝑋, 𝑌})
40	27, 39	mpbir 221	. . . 4 ⊢ 𝑃:(0...(#‘𝐹))⟶{𝑋, 𝑌}
41	2, 12, 5, 6, 14	wlk2v2elem2 27016	. . . 4 ⊢ ∀𝑘 ∈ (0..^(#‘𝐹))(𝐼‘(𝐹‘𝑘)) = {(𝑃‘𝑘), (𝑃‘(𝑘 + 1))}
42	13, 40, 41	3pm3.2i 1239	. . 3 ⊢ (𝐹 ∈ Word dom 𝐼 ∧ 𝑃:(0...(#‘𝐹))⟶{𝑋, 𝑌} ∧ ∀𝑘 ∈ (0..^(#‘𝐹))(𝐼‘(𝐹‘𝑘)) = {(𝑃‘𝑘), (𝑃‘(𝑘 + 1))})
43	1	fveq2i 6194	. . . . 5 ⊢ (Vtx‘𝐺) = (Vtx‘⟨{𝑋, 𝑌}, 𝐼⟩)
44		prex 4909	. . . . . 6 ⊢ {𝑋, 𝑌} ∈ V
45		s1cli 13384	. . . . . . 7 ⊢ ⟨“{𝑋, 𝑌}”⟩ ∈ Word V
46	2, 45	eqeltri 2697	. . . . . 6 ⊢ 𝐼 ∈ Word V
47		opvtxfv 25884	. . . . . 6 ⊢ (({𝑋, 𝑌} ∈ V ∧ 𝐼 ∈ Word V) → (Vtx‘⟨{𝑋, 𝑌}, 𝐼⟩) = {𝑋, 𝑌})
48	44, 46, 47	mp2an 708	. . . . 5 ⊢ (Vtx‘⟨{𝑋, 𝑌}, 𝐼⟩) = {𝑋, 𝑌}
49	43, 48	eqtr2i 2645	. . . 4 ⊢ {𝑋, 𝑌} = (Vtx‘𝐺)
50	1	fveq2i 6194	. . . . 5 ⊢ (iEdg‘𝐺) = (iEdg‘⟨{𝑋, 𝑌}, 𝐼⟩)
51		opiedgfv 25887	. . . . . 6 ⊢ (({𝑋, 𝑌} ∈ V ∧ 𝐼 ∈ Word V) → (iEdg‘⟨{𝑋, 𝑌}, 𝐼⟩) = 𝐼)
52	44, 46, 51	mp2an 708	. . . . 5 ⊢ (iEdg‘⟨{𝑋, 𝑌}, 𝐼⟩) = 𝐼
53	50, 52	eqtr2i 2645	. . . 4 ⊢ 𝐼 = (iEdg‘𝐺)
54	49, 53	upgriswlk 26537	. . 3 ⊢ (𝐺 ∈ UPGraph → (𝐹(Walks‘𝐺)𝑃 ↔ (𝐹 ∈ Word dom 𝐼 ∧ 𝑃:(0...(#‘𝐹))⟶{𝑋, 𝑌} ∧ ∀𝑘 ∈ (0..^(#‘𝐹))(𝐼‘(𝐹‘𝑘)) = {(𝑃‘𝑘), (𝑃‘(𝑘 + 1))})))
55	42, 54	mpbiri 248	. 2 ⊢ (𝐺 ∈ UPGraph → 𝐹(Walks‘𝐺)𝑃)
56	11, 55	ax-mp 5	1 ⊢ 𝐹(Walks‘𝐺)𝑃

Syntax hints:   ∧ w3a 1037   = wceq 1483   ∈ wcel 1990  ∀wral 2912  Vcvv 3200  {cpr 4179  ⟨cop 4183   class class class wbr 4653  dom cdm 5114  ⟶wf 5884  ‘cfv 5888  (class class class)co 6650  0cc0 9936  1c1 9937   + caddc 9939   − cmin 10266  2c2 11070  3c3 11071  ℤcz 11377  ...cfz 12326  ..^cfzo 12465  #chash 13117  Word cword 13291  ⟨“cs1 13294  ⟨“cs2 13586  ⟨“cs3 13587  Vtxcvtx 25874  iEdgciedg 25875   UPGraph cupgr 25975   USPGraph cuspgr 26043  Walkscwlks 26492

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1722  ax-4 1737  ax-5 1839  ax-6 1888  ax-7 1935  ax-8 1992  ax-9 1999  ax-10 2019  ax-11 2034  ax-12 2047  ax-13 2246  ax-ext 2602  ax-rep 4771  ax-sep 4781  ax-nul 4789  ax-pow 4843  ax-pr 4906  ax-un 6949  ax-cnex 9992  ax-resscn 9993  ax-1cn 9994  ax-icn 9995  ax-addcl 9996  ax-addrcl 9997  ax-mulcl 9998  ax-mulrcl 9999  ax-mulcom 10000  ax-addass 10001  ax-mulass 10002  ax-distr 10003  ax-i2m1 10004  ax-1ne0 10005  ax-1rid 10006  ax-rnegex 10007  ax-rrecex 10008  ax-cnre 10009  ax-pre-lttri 10010  ax-pre-lttrn 10011  ax-pre-ltadd 10012  ax-pre-mulgt0 10013

This theorem depends on definitions:  df-bi 197  df-or 385  df-an 386  df-ifp 1013  df-3or 1038  df-3an 1039  df-tru 1486  df-ex 1705  df-nf 1710  df-sb 1881  df-eu 2474  df-mo 2475  df-clab 2609  df-cleq 2615  df-clel 2618  df-nfc 2753  df-ne 2795  df-nel 2898  df-ral 2917  df-rex 2918  df-reu 2919  df-rmo 2920  df-rab 2921  df-v 3202  df-sbc 3436  df-csb 3534  df-dif 3577  df-un 3579  df-in 3581  df-ss 3588  df-pss 3590  df-nul 3916  df-if 4087  df-pw 4160  df-sn 4178  df-pr 4180  df-tp 4182  df-op 4184  df-uni 4437  df-int 4476  df-iun 4522  df-br 4654  df-opab 4713  df-mpt 4730  df-tr 4753  df-id 5024  df-eprel 5029  df-po 5035  df-so 5036  df-fr 5073  df-we 5075  df-xp 5120  df-rel 5121  df-cnv 5122  df-co 5123  df-dm 5124  df-rn 5125  df-res 5126  df-ima 5127  df-pred 5680  df-ord 5726  df-on 5727  df-lim 5728  df-suc 5729  df-iota 5851  df-fun 5890  df-fn 5891  df-f 5892  df-f1 5893  df-fo 5894  df-f1o 5895  df-fv 5896  df-riota 6611  df-ov 6653  df-oprab 6654  df-mpt2 6655  df-om 7066  df-1st 7168  df-2nd 7169  df-wrecs 7407  df-recs 7468  df-rdg 7506  df-1o 7560  df-2o 7561  df-oadd 7564  df-er 7742  df-map 7859  df-pm 7860  df-en 7956  df-dom 7957  df-sdom 7958  df-fin 7959  df-card 8765  df-cda 8990  df-pnf 10076  df-mnf 10077  df-xr 10078  df-ltxr 10079  df-le 10080  df-sub 10268  df-neg 10269  df-nn 11021  df-2 11079  df-3 11080  df-n0 11293  df-xnn0 11364  df-z 11378  df-uz 11688  df-fz 12327  df-fzo 12466  df-hash 13118  df-word 13299  df-concat 13301  df-s1 13302  df-s2 13593  df-s3 13594  df-vtx 25876  df-iedg 25877  df-edg 25940  df-uhgr 25953  df-upgr 25977  df-uspgr 26045  df-wlks 26495

This theorem is referenced by: (None)