Theorem nbusgredgeu0 29353

Description: For each neighbor of a vertex there is exactly one edge between the vertex and its neighbor in a simple graph. (Contributed by Alexander van der Vekens, 17-Dec-2017.) (Revised by AV, 27-Oct-2020.) (Proof shortened by AV, 13-Feb-2022.)

Hypotheses

Ref	Expression
nbusgrf1o1.v	⊢ 𝑉 = (Vtx‘𝐺)
nbusgrf1o1.e	⊢ 𝐸 = (Edg‘𝐺)
nbusgrf1o1.n	⊢ 𝑁 = (𝐺 NeighbVtx 𝑈)
nbusgrf1o1.i	⊢ 𝐼 = {𝑒 ∈ 𝐸 ∣ 𝑈 ∈ 𝑒}

Assertion

Ref	Expression
nbusgredgeu0	⊢ (((𝐺 ∈ USGraph ∧ 𝑈 ∈ 𝑉) ∧ 𝑀 ∈ 𝑁) → ∃!𝑖 ∈ 𝐼 𝑖 = {𝑈, 𝑀})

Distinct variable groups:   𝑖,𝐸,𝑒   𝑖,𝐺   𝑖,𝑀   𝑖,𝑁   𝑈,𝑖,𝑒   𝑖,𝑉

Allowed substitution hints:   𝐺(𝑒)   𝐼(𝑒,𝑖)   𝑀(𝑒)   𝑁(𝑒)   𝑉(𝑒)

Proof of Theorem nbusgredgeu0

Step	Hyp	Ref	Expression
1		simpll 766	. . . . 5 ⊢ (((𝐺 ∈ USGraph ∧ 𝑈 ∈ 𝑉) ∧ 𝑀 ∈ 𝑁) → 𝐺 ∈ USGraph)
2		nbusgrf1o1.n	. . . . . . . 8 ⊢ 𝑁 = (𝐺 NeighbVtx 𝑈)
3	2	eleq2i 2823	. . . . . . 7 ⊢ (𝑀 ∈ 𝑁 ↔ 𝑀 ∈ (𝐺 NeighbVtx 𝑈))
4		nbgrsym 29348	. . . . . . . . 9 ⊢ (𝑀 ∈ (𝐺 NeighbVtx 𝑈) ↔ 𝑈 ∈ (𝐺 NeighbVtx 𝑀))
5	4	a1i 11	. . . . . . . 8 ⊢ ((𝐺 ∈ USGraph ∧ 𝑈 ∈ 𝑉) → (𝑀 ∈ (𝐺 NeighbVtx 𝑈) ↔ 𝑈 ∈ (𝐺 NeighbVtx 𝑀)))
6	5	biimpd 229	. . . . . . 7 ⊢ ((𝐺 ∈ USGraph ∧ 𝑈 ∈ 𝑉) → (𝑀 ∈ (𝐺 NeighbVtx 𝑈) → 𝑈 ∈ (𝐺 NeighbVtx 𝑀)))
7	3, 6	biimtrid 242	. . . . . 6 ⊢ ((𝐺 ∈ USGraph ∧ 𝑈 ∈ 𝑉) → (𝑀 ∈ 𝑁 → 𝑈 ∈ (𝐺 NeighbVtx 𝑀)))
8	7	imp 406	. . . . 5 ⊢ (((𝐺 ∈ USGraph ∧ 𝑈 ∈ 𝑉) ∧ 𝑀 ∈ 𝑁) → 𝑈 ∈ (𝐺 NeighbVtx 𝑀))
9		nbusgrf1o1.e	. . . . . 6 ⊢ 𝐸 = (Edg‘𝐺)
10	9	nbusgredgeu 29351	. . . . 5 ⊢ ((𝐺 ∈ USGraph ∧ 𝑈 ∈ (𝐺 NeighbVtx 𝑀)) → ∃!𝑖 ∈ 𝐸 𝑖 = {𝑈, 𝑀})
11	1, 8, 10	syl2anc 584	. . . 4 ⊢ (((𝐺 ∈ USGraph ∧ 𝑈 ∈ 𝑉) ∧ 𝑀 ∈ 𝑁) → ∃!𝑖 ∈ 𝐸 𝑖 = {𝑈, 𝑀})
12		df-reu 3347	. . . 4 ⊢ (∃!𝑖 ∈ 𝐸 𝑖 = {𝑈, 𝑀} ↔ ∃!𝑖(𝑖 ∈ 𝐸 ∧ 𝑖 = {𝑈, 𝑀}))
13	11, 12	sylib 218	. . 3 ⊢ (((𝐺 ∈ USGraph ∧ 𝑈 ∈ 𝑉) ∧ 𝑀 ∈ 𝑁) → ∃!𝑖(𝑖 ∈ 𝐸 ∧ 𝑖 = {𝑈, 𝑀}))
14		anass 468	. . . . 5 ⊢ (((𝑖 ∈ 𝐸 ∧ 𝑈 ∈ 𝑖) ∧ 𝑖 = {𝑈, 𝑀}) ↔ (𝑖 ∈ 𝐸 ∧ (𝑈 ∈ 𝑖 ∧ 𝑖 = {𝑈, 𝑀})))
15		prid1g 4712	. . . . . . . . . 10 ⊢ (𝑈 ∈ 𝑉 → 𝑈 ∈ {𝑈, 𝑀})
16	15	ad2antlr 727	. . . . . . . . 9 ⊢ (((𝐺 ∈ USGraph ∧ 𝑈 ∈ 𝑉) ∧ 𝑀 ∈ 𝑁) → 𝑈 ∈ {𝑈, 𝑀})
17		eleq2 2820	. . . . . . . . 9 ⊢ (𝑖 = {𝑈, 𝑀} → (𝑈 ∈ 𝑖 ↔ 𝑈 ∈ {𝑈, 𝑀}))
18	16, 17	syl5ibrcom 247	. . . . . . . 8 ⊢ (((𝐺 ∈ USGraph ∧ 𝑈 ∈ 𝑉) ∧ 𝑀 ∈ 𝑁) → (𝑖 = {𝑈, 𝑀} → 𝑈 ∈ 𝑖))
19	18	pm4.71rd 562	. . . . . . 7 ⊢ (((𝐺 ∈ USGraph ∧ 𝑈 ∈ 𝑉) ∧ 𝑀 ∈ 𝑁) → (𝑖 = {𝑈, 𝑀} ↔ (𝑈 ∈ 𝑖 ∧ 𝑖 = {𝑈, 𝑀})))
20	19	bicomd 223	. . . . . 6 ⊢ (((𝐺 ∈ USGraph ∧ 𝑈 ∈ 𝑉) ∧ 𝑀 ∈ 𝑁) → ((𝑈 ∈ 𝑖 ∧ 𝑖 = {𝑈, 𝑀}) ↔ 𝑖 = {𝑈, 𝑀}))
21	20	anbi2d 630	. . . . 5 ⊢ (((𝐺 ∈ USGraph ∧ 𝑈 ∈ 𝑉) ∧ 𝑀 ∈ 𝑁) → ((𝑖 ∈ 𝐸 ∧ (𝑈 ∈ 𝑖 ∧ 𝑖 = {𝑈, 𝑀})) ↔ (𝑖 ∈ 𝐸 ∧ 𝑖 = {𝑈, 𝑀})))
22	14, 21	bitrid 283	. . . 4 ⊢ (((𝐺 ∈ USGraph ∧ 𝑈 ∈ 𝑉) ∧ 𝑀 ∈ 𝑁) → (((𝑖 ∈ 𝐸 ∧ 𝑈 ∈ 𝑖) ∧ 𝑖 = {𝑈, 𝑀}) ↔ (𝑖 ∈ 𝐸 ∧ 𝑖 = {𝑈, 𝑀})))
23	22	eubidv 2581	. . 3 ⊢ (((𝐺 ∈ USGraph ∧ 𝑈 ∈ 𝑉) ∧ 𝑀 ∈ 𝑁) → (∃!𝑖((𝑖 ∈ 𝐸 ∧ 𝑈 ∈ 𝑖) ∧ 𝑖 = {𝑈, 𝑀}) ↔ ∃!𝑖(𝑖 ∈ 𝐸 ∧ 𝑖 = {𝑈, 𝑀})))
24	13, 23	mpbird 257	. 2 ⊢ (((𝐺 ∈ USGraph ∧ 𝑈 ∈ 𝑉) ∧ 𝑀 ∈ 𝑁) → ∃!𝑖((𝑖 ∈ 𝐸 ∧ 𝑈 ∈ 𝑖) ∧ 𝑖 = {𝑈, 𝑀}))
25		df-reu 3347	. . 3 ⊢ (∃!𝑖 ∈ 𝐼 𝑖 = {𝑈, 𝑀} ↔ ∃!𝑖(𝑖 ∈ 𝐼 ∧ 𝑖 = {𝑈, 𝑀}))
26		eleq2 2820	. . . . . 6 ⊢ (𝑒 = 𝑖 → (𝑈 ∈ 𝑒 ↔ 𝑈 ∈ 𝑖))
27		nbusgrf1o1.i	. . . . . 6 ⊢ 𝐼 = {𝑒 ∈ 𝐸 ∣ 𝑈 ∈ 𝑒}
28	26, 27	elrab2 3645	. . . . 5 ⊢ (𝑖 ∈ 𝐼 ↔ (𝑖 ∈ 𝐸 ∧ 𝑈 ∈ 𝑖))
29	28	anbi1i 624	. . . 4 ⊢ ((𝑖 ∈ 𝐼 ∧ 𝑖 = {𝑈, 𝑀}) ↔ ((𝑖 ∈ 𝐸 ∧ 𝑈 ∈ 𝑖) ∧ 𝑖 = {𝑈, 𝑀}))
30	29	eubii 2580	. . 3 ⊢ (∃!𝑖(𝑖 ∈ 𝐼 ∧ 𝑖 = {𝑈, 𝑀}) ↔ ∃!𝑖((𝑖 ∈ 𝐸 ∧ 𝑈 ∈ 𝑖) ∧ 𝑖 = {𝑈, 𝑀}))
31	25, 30	bitri 275	. 2 ⊢ (∃!𝑖 ∈ 𝐼 𝑖 = {𝑈, 𝑀} ↔ ∃!𝑖((𝑖 ∈ 𝐸 ∧ 𝑈 ∈ 𝑖) ∧ 𝑖 = {𝑈, 𝑀}))
32	24, 31	sylibr 234	1 ⊢ (((𝐺 ∈ USGraph ∧ 𝑈 ∈ 𝑉) ∧ 𝑀 ∈ 𝑁) → ∃!𝑖 ∈ 𝐼 𝑖 = {𝑈, 𝑀})

Syntax hints:   → wi 4   ↔ wb 206   ∧ wa 395   = wceq 1541   ∈ wcel 2111  ∃!weu 2563  ∃!wreu 3344  {crab 3395  {cpr 4577  ‘cfv 6487  (class class class)co 7352  Vtxcvtx 28981  Edgcedg 29032  USGraphcusgr 29134   NeighbVtx cnbgr 29317

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1796  ax-4 1810  ax-5 1911  ax-6 1968  ax-7 2009  ax-8 2113  ax-9 2121  ax-10 2144  ax-11 2160  ax-12 2180  ax-ext 2703  ax-sep 5236  ax-nul 5246  ax-pow 5305  ax-pr 5372  ax-un 7674  ax-cnex 11068  ax-resscn 11069  ax-1cn 11070  ax-icn 11071  ax-addcl 11072  ax-addrcl 11073  ax-mulcl 11074  ax-mulrcl 11075  ax-mulcom 11076  ax-addass 11077  ax-mulass 11078  ax-distr 11079  ax-i2m1 11080  ax-1ne0 11081  ax-1rid 11082  ax-rnegex 11083  ax-rrecex 11084  ax-cnre 11085  ax-pre-lttri 11086  ax-pre-lttrn 11087  ax-pre-ltadd 11088  ax-pre-mulgt0 11089

This theorem depends on definitions:  df-bi 207  df-an 396  df-or 848  df-3or 1087  df-3an 1088  df-tru 1544  df-fal 1554  df-ex 1781  df-nf 1785  df-sb 2068  df-mo 2535  df-eu 2564  df-clab 2710  df-cleq 2723  df-clel 2806  df-nfc 2881  df-ne 2929  df-nel 3033  df-ral 3048  df-rex 3057  df-rmo 3346  df-reu 3347  df-rab 3396  df-v 3438  df-sbc 3737  df-csb 3846  df-dif 3900  df-un 3902  df-in 3904  df-ss 3914  df-pss 3917  df-nul 4283  df-if 4475  df-pw 4551  df-sn 4576  df-pr 4578  df-op 4582  df-uni 4859  df-int 4898  df-iun 4943  df-br 5094  df-opab 5156  df-mpt 5175  df-tr 5201  df-id 5514  df-eprel 5519  df-po 5527  df-so 5528  df-fr 5572  df-we 5574  df-xp 5625  df-rel 5626  df-cnv 5627  df-co 5628  df-dm 5629  df-rn 5630  df-res 5631  df-ima 5632  df-pred 6254  df-ord 6315  df-on 6316  df-lim 6317  df-suc 6318  df-iota 6443  df-fun 6489  df-fn 6490  df-f 6491  df-f1 6492  df-fo 6493  df-f1o 6494  df-fv 6495  df-riota 7309  df-ov 7355  df-oprab 7356  df-mpo 7357  df-om 7803  df-1st 7927  df-2nd 7928  df-frecs 8217  df-wrecs 8248  df-recs 8297  df-rdg 8335  df-1o 8391  df-2o 8392  df-oadd 8395  df-er 8628  df-en 8876  df-dom 8877  df-sdom 8878  df-fin 8879  df-dju 9800  df-card 9838  df-pnf 11154  df-mnf 11155  df-xr 11156  df-ltxr 11157  df-le 11158  df-sub 11352  df-neg 11353  df-nn 12132  df-2 12194  df-n0 12388  df-xnn0 12461  df-z 12475  df-uz 12739  df-fz 13414  df-hash 14244  df-edg 29033  df-upgr 29067  df-umgr 29068  df-usgr 29136  df-nbgr 29318

This theorem is referenced by: (None)