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Theorem tz6.26OLD 6349
Description: Obsolete proof of tz6.26 6348 as of 17-Nov-2024. (New usage is discouraged.) (Proof modification is discouraged.) (Contributed by Scott Fenton, 29-Jan-2011.) (Revised by Mario Carneiro, 26-Jun-2015.)
Assertion
Ref Expression
tz6.26OLD (((𝑅 We 𝐴𝑅 Se 𝐴) ∧ (𝐵𝐴𝐵 ≠ ∅)) → ∃𝑦𝐵 Pred(𝑅, 𝐵, 𝑦) = ∅)
Distinct variable groups:   𝑦,𝐴   𝑦,𝐵   𝑦,𝑅

Proof of Theorem tz6.26OLD
Dummy variable 𝑥 is distinct from all other variables.
StepHypRef Expression
1 wereu2 5673 . . 3 (((𝑅 We 𝐴𝑅 Se 𝐴) ∧ (𝐵𝐴𝐵 ≠ ∅)) → ∃!𝑦𝐵𝑥𝐵 ¬ 𝑥𝑅𝑦)
2 reurex 3380 . . 3 (∃!𝑦𝐵𝑥𝐵 ¬ 𝑥𝑅𝑦 → ∃𝑦𝐵𝑥𝐵 ¬ 𝑥𝑅𝑦)
31, 2syl 17 . 2 (((𝑅 We 𝐴𝑅 Se 𝐴) ∧ (𝐵𝐴𝐵 ≠ ∅)) → ∃𝑦𝐵𝑥𝐵 ¬ 𝑥𝑅𝑦)
4 rabeq0 4384 . . . 4 ({𝑥𝐵𝑥𝑅𝑦} = ∅ ↔ ∀𝑥𝐵 ¬ 𝑥𝑅𝑦)
5 dfrab3 4309 . . . . . 6 {𝑥𝐵𝑥𝑅𝑦} = (𝐵 ∩ {𝑥𝑥𝑅𝑦})
6 vex 3478 . . . . . . 7 𝑦 ∈ V
76dfpred2 6310 . . . . . 6 Pred(𝑅, 𝐵, 𝑦) = (𝐵 ∩ {𝑥𝑥𝑅𝑦})
85, 7eqtr4i 2763 . . . . 5 {𝑥𝐵𝑥𝑅𝑦} = Pred(𝑅, 𝐵, 𝑦)
98eqeq1i 2737 . . . 4 ({𝑥𝐵𝑥𝑅𝑦} = ∅ ↔ Pred(𝑅, 𝐵, 𝑦) = ∅)
104, 9bitr3i 276 . . 3 (∀𝑥𝐵 ¬ 𝑥𝑅𝑦 ↔ Pred(𝑅, 𝐵, 𝑦) = ∅)
1110rexbii 3094 . 2 (∃𝑦𝐵𝑥𝐵 ¬ 𝑥𝑅𝑦 ↔ ∃𝑦𝐵 Pred(𝑅, 𝐵, 𝑦) = ∅)
123, 11sylib 217 1 (((𝑅 We 𝐴𝑅 Se 𝐴) ∧ (𝐵𝐴𝐵 ≠ ∅)) → ∃𝑦𝐵 Pred(𝑅, 𝐵, 𝑦) = ∅)
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4  wa 396   = wceq 1541  {cab 2709  wne 2940  wral 3061  wrex 3070  ∃!wreu 3374  {crab 3432  cin 3947  wss 3948  c0 4322   class class class wbr 5148   Se wse 5629   We wwe 5630  Predcpred 6299
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1797  ax-4 1811  ax-5 1913  ax-6 1971  ax-7 2011  ax-8 2108  ax-9 2116  ax-10 2137  ax-11 2154  ax-12 2171  ax-ext 2703  ax-sep 5299  ax-nul 5306  ax-pr 5427
This theorem depends on definitions:  df-bi 206  df-an 397  df-or 846  df-3or 1088  df-3an 1089  df-tru 1544  df-fal 1554  df-ex 1782  df-nf 1786  df-sb 2068  df-mo 2534  df-eu 2563  df-clab 2710  df-cleq 2724  df-clel 2810  df-nfc 2885  df-ne 2941  df-ral 3062  df-rex 3071  df-rmo 3376  df-reu 3377  df-rab 3433  df-v 3476  df-dif 3951  df-un 3953  df-in 3955  df-ss 3965  df-nul 4323  df-if 4529  df-pw 4604  df-sn 4629  df-pr 4631  df-op 4635  df-br 5149  df-opab 5211  df-po 5588  df-so 5589  df-fr 5631  df-se 5632  df-we 5633  df-xp 5682  df-cnv 5684  df-dm 5686  df-rn 5687  df-res 5688  df-ima 5689  df-pred 6300
This theorem is referenced by: (None)
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