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Theorem frgrncvvdeqlem7 28076
 Description: Lemma 7 for frgrncvvdeq 28080. This corresponds to statement 1 in [Huneke] p. 1: "This common neighbor cannot be x, as x and y are not adjacent.". This is only an observation, which is not required to proof the friendship theorem. (Contributed by Alexander van der Vekens, 23-Dec-2017.) (Revised by AV, 10-May-2021.)
Hypotheses
Ref Expression
frgrncvvdeq.v1 𝑉 = (Vtx‘𝐺)
frgrncvvdeq.e 𝐸 = (Edg‘𝐺)
frgrncvvdeq.nx 𝐷 = (𝐺 NeighbVtx 𝑋)
frgrncvvdeq.ny 𝑁 = (𝐺 NeighbVtx 𝑌)
frgrncvvdeq.x (𝜑𝑋𝑉)
frgrncvvdeq.y (𝜑𝑌𝑉)
frgrncvvdeq.ne (𝜑𝑋𝑌)
frgrncvvdeq.xy (𝜑𝑌𝐷)
frgrncvvdeq.f (𝜑𝐺 ∈ FriendGraph )
frgrncvvdeq.a 𝐴 = (𝑥𝐷 ↦ (𝑦𝑁 {𝑥, 𝑦} ∈ 𝐸))
Assertion
Ref Expression
frgrncvvdeqlem7 (𝜑 → ∀𝑥𝐷 (𝐴𝑥) ≠ 𝑋)
Distinct variable groups:   𝑦,𝐸   𝑦,𝐺   𝑦,𝑉   𝑦,𝑌   𝑥,𝑦,𝑁   𝑥,𝐷   𝑥,𝑁   𝜑,𝑥
Allowed substitution hints:   𝜑(𝑦)   𝐴(𝑥,𝑦)   𝐷(𝑦)   𝐸(𝑥)   𝐺(𝑥)   𝑉(𝑥)   𝑋(𝑥,𝑦)   𝑌(𝑥)

Proof of Theorem frgrncvvdeqlem7
StepHypRef Expression
1 frgrncvvdeq.v1 . . . 4 𝑉 = (Vtx‘𝐺)
2 frgrncvvdeq.e . . . 4 𝐸 = (Edg‘𝐺)
3 frgrncvvdeq.nx . . . 4 𝐷 = (𝐺 NeighbVtx 𝑋)
4 frgrncvvdeq.ny . . . 4 𝑁 = (𝐺 NeighbVtx 𝑌)
5 frgrncvvdeq.x . . . 4 (𝜑𝑋𝑉)
6 frgrncvvdeq.y . . . 4 (𝜑𝑌𝑉)
7 frgrncvvdeq.ne . . . 4 (𝜑𝑋𝑌)
8 frgrncvvdeq.xy . . . 4 (𝜑𝑌𝐷)
9 frgrncvvdeq.f . . . 4 (𝜑𝐺 ∈ FriendGraph )
10 frgrncvvdeq.a . . . 4 𝐴 = (𝑥𝐷 ↦ (𝑦𝑁 {𝑥, 𝑦} ∈ 𝐸))
111, 2, 3, 4, 5, 6, 7, 8, 9, 10frgrncvvdeqlem5 28074 . . 3 ((𝜑𝑥𝐷) → {(𝐴𝑥)} = ((𝐺 NeighbVtx 𝑥) ∩ 𝑁))
12 fvex 6676 . . . . 5 (𝐴𝑥) ∈ V
1312snid 4593 . . . 4 (𝐴𝑥) ∈ {(𝐴𝑥)}
14 eleq2 2899 . . . . . 6 ({(𝐴𝑥)} = ((𝐺 NeighbVtx 𝑥) ∩ 𝑁) → ((𝐴𝑥) ∈ {(𝐴𝑥)} ↔ (𝐴𝑥) ∈ ((𝐺 NeighbVtx 𝑥) ∩ 𝑁)))
1514biimpa 479 . . . . 5 (({(𝐴𝑥)} = ((𝐺 NeighbVtx 𝑥) ∩ 𝑁) ∧ (𝐴𝑥) ∈ {(𝐴𝑥)}) → (𝐴𝑥) ∈ ((𝐺 NeighbVtx 𝑥) ∩ 𝑁))
16 elin 4167 . . . . . 6 ((𝐴𝑥) ∈ ((𝐺 NeighbVtx 𝑥) ∩ 𝑁) ↔ ((𝐴𝑥) ∈ (𝐺 NeighbVtx 𝑥) ∧ (𝐴𝑥) ∈ 𝑁))
171, 2, 3, 4, 5, 6, 7, 8, 9, 10frgrncvvdeqlem1 28070 . . . . . . . . 9 (𝜑𝑋𝑁)
18 df-nel 3122 . . . . . . . . . 10 (𝑋𝑁 ↔ ¬ 𝑋𝑁)
19 nelelne 3115 . . . . . . . . . 10 𝑋𝑁 → ((𝐴𝑥) ∈ 𝑁 → (𝐴𝑥) ≠ 𝑋))
2018, 19sylbi 219 . . . . . . . . 9 (𝑋𝑁 → ((𝐴𝑥) ∈ 𝑁 → (𝐴𝑥) ≠ 𝑋))
2117, 20syl 17 . . . . . . . 8 (𝜑 → ((𝐴𝑥) ∈ 𝑁 → (𝐴𝑥) ≠ 𝑋))
2221adantr 483 . . . . . . 7 ((𝜑𝑥𝐷) → ((𝐴𝑥) ∈ 𝑁 → (𝐴𝑥) ≠ 𝑋))
2322com12 32 . . . . . 6 ((𝐴𝑥) ∈ 𝑁 → ((𝜑𝑥𝐷) → (𝐴𝑥) ≠ 𝑋))
2416, 23simplbiim 507 . . . . 5 ((𝐴𝑥) ∈ ((𝐺 NeighbVtx 𝑥) ∩ 𝑁) → ((𝜑𝑥𝐷) → (𝐴𝑥) ≠ 𝑋))
2515, 24syl 17 . . . 4 (({(𝐴𝑥)} = ((𝐺 NeighbVtx 𝑥) ∩ 𝑁) ∧ (𝐴𝑥) ∈ {(𝐴𝑥)}) → ((𝜑𝑥𝐷) → (𝐴𝑥) ≠ 𝑋))
2613, 25mpan2 689 . . 3 ({(𝐴𝑥)} = ((𝐺 NeighbVtx 𝑥) ∩ 𝑁) → ((𝜑𝑥𝐷) → (𝐴𝑥) ≠ 𝑋))
2711, 26mpcom 38 . 2 ((𝜑𝑥𝐷) → (𝐴𝑥) ≠ 𝑋)
2827ralrimiva 3180 1 (𝜑 → ∀𝑥𝐷 (𝐴𝑥) ≠ 𝑋)
 Colors of variables: wff setvar class Syntax hints:  ¬ wn 3   → wi 4   ∧ wa 398   = wceq 1530   ∈ wcel 2107   ≠ wne 3014   ∉ wnel 3121  ∀wral 3136   ∩ cin 3933  {csn 4559  {cpr 4561   ↦ cmpt 5137  ‘cfv 6348  ℩crio 7105  (class class class)co 7148  Vtxcvtx 26773  Edgcedg 26824   NeighbVtx cnbgr 27106   FriendGraph cfrgr 28029 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1789  ax-4 1803  ax-5 1904  ax-6 1963  ax-7 2008  ax-8 2109  ax-9 2117  ax-10 2138  ax-11 2153  ax-12 2169  ax-ext 2791  ax-rep 5181  ax-sep 5194  ax-nul 5201  ax-pow 5257  ax-pr 5320  ax-un 7453  ax-cnex 10585  ax-resscn 10586  ax-1cn 10587  ax-icn 10588  ax-addcl 10589  ax-addrcl 10590  ax-mulcl 10591  ax-mulrcl 10592  ax-mulcom 10593  ax-addass 10594  ax-mulass 10595  ax-distr 10596  ax-i2m1 10597  ax-1ne0 10598  ax-1rid 10599  ax-rnegex 10600  ax-rrecex 10601  ax-cnre 10602  ax-pre-lttri 10603  ax-pre-lttrn 10604  ax-pre-ltadd 10605  ax-pre-mulgt0 10606 This theorem depends on definitions:  df-bi 209  df-an 399  df-or 844  df-3or 1082  df-3an 1083  df-tru 1533  df-fal 1543  df-ex 1774  df-nf 1778  df-sb 2063  df-mo 2616  df-eu 2648  df-clab 2798  df-cleq 2812  df-clel 2891  df-nfc 2961  df-ne 3015  df-nel 3122  df-ral 3141  df-rex 3142  df-reu 3143  df-rmo 3144  df-rab 3145  df-v 3495  df-sbc 3771  df-csb 3882  df-dif 3937  df-un 3939  df-in 3941  df-ss 3950  df-pss 3952  df-nul 4290  df-if 4466  df-pw 4539  df-sn 4560  df-pr 4562  df-tp 4564  df-op 4566  df-uni 4831  df-int 4868  df-iun 4912  df-br 5058  df-opab 5120  df-mpt 5138  df-tr 5164  df-id 5453  df-eprel 5458  df-po 5467  df-so 5468  df-fr 5507  df-we 5509  df-xp 5554  df-rel 5555  df-cnv 5556  df-co 5557  df-dm 5558  df-rn 5559  df-res 5560  df-ima 5561  df-pred 6141  df-ord 6187  df-on 6188  df-lim 6189  df-suc 6190  df-iota 6307  df-fun 6350  df-fn 6351  df-f 6352  df-f1 6353  df-fo 6354  df-f1o 6355  df-fv 6356  df-riota 7106  df-ov 7151  df-oprab 7152  df-mpo 7153  df-om 7573  df-1st 7681  df-2nd 7682  df-wrecs 7939  df-recs 8000  df-rdg 8038  df-1o 8094  df-2o 8095  df-oadd 8098  df-er 8281  df-en 8502  df-dom 8503  df-sdom 8504  df-fin 8505  df-dju 9322  df-card 9360  df-pnf 10669  df-mnf 10670  df-xr 10671  df-ltxr 10672  df-le 10673  df-sub 10864  df-neg 10865  df-nn 11631  df-2 11692  df-n0 11890  df-xnn0 11960  df-z 11974  df-uz 12236  df-fz 12885  df-hash 13683  df-edg 26825  df-upgr 26859  df-umgr 26860  df-usgr 26928  df-nbgr 27107  df-frgr 28030 This theorem is referenced by: (None)
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