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Theorem untsucf 30647
Description: If a class is untangled, then so is its successor. (Contributed by Scott Fenton, 28-Feb-2011.) (Revised by Mario Carneiro, 11-Dec-2016.)
Hypothesis
Ref Expression
untsucf.1 𝑦𝐴
Assertion
Ref Expression
untsucf (∀𝑥𝐴 ¬ 𝑥𝑥 → ∀𝑦 ∈ suc 𝐴 ¬ 𝑦𝑦)
Distinct variable groups:   𝑥,𝐴   𝑥,𝑦
Allowed substitution hint:   𝐴(𝑦)

Proof of Theorem untsucf
StepHypRef Expression
1 untsucf.1 . . 3 𝑦𝐴
2 nfv 1829 . . 3 𝑦 ¬ 𝑥𝑥
31, 2nfral 2928 . 2 𝑦𝑥𝐴 ¬ 𝑥𝑥
4 vex 3175 . . . 4 𝑦 ∈ V
54elsuc 5697 . . 3 (𝑦 ∈ suc 𝐴 ↔ (𝑦𝐴𝑦 = 𝐴))
6 elequ1 1983 . . . . . . 7 (𝑥 = 𝑦 → (𝑥𝑥𝑦𝑥))
7 elequ2 1990 . . . . . . 7 (𝑥 = 𝑦 → (𝑦𝑥𝑦𝑦))
86, 7bitrd 266 . . . . . 6 (𝑥 = 𝑦 → (𝑥𝑥𝑦𝑦))
98notbid 306 . . . . 5 (𝑥 = 𝑦 → (¬ 𝑥𝑥 ↔ ¬ 𝑦𝑦))
109rspccv 3278 . . . 4 (∀𝑥𝐴 ¬ 𝑥𝑥 → (𝑦𝐴 → ¬ 𝑦𝑦))
11 untelirr 30645 . . . . 5 (∀𝑥𝐴 ¬ 𝑥𝑥 → ¬ 𝐴𝐴)
12 eleq1 2675 . . . . . . 7 (𝑦 = 𝐴 → (𝑦𝑦𝐴𝑦))
13 eleq2 2676 . . . . . . 7 (𝑦 = 𝐴 → (𝐴𝑦𝐴𝐴))
1412, 13bitrd 266 . . . . . 6 (𝑦 = 𝐴 → (𝑦𝑦𝐴𝐴))
1514notbid 306 . . . . 5 (𝑦 = 𝐴 → (¬ 𝑦𝑦 ↔ ¬ 𝐴𝐴))
1611, 15syl5ibrcom 235 . . . 4 (∀𝑥𝐴 ¬ 𝑥𝑥 → (𝑦 = 𝐴 → ¬ 𝑦𝑦))
1710, 16jaod 393 . . 3 (∀𝑥𝐴 ¬ 𝑥𝑥 → ((𝑦𝐴𝑦 = 𝐴) → ¬ 𝑦𝑦))
185, 17syl5bi 230 . 2 (∀𝑥𝐴 ¬ 𝑥𝑥 → (𝑦 ∈ suc 𝐴 → ¬ 𝑦𝑦))
193, 18ralrimi 2939 1 (∀𝑥𝐴 ¬ 𝑥𝑥 → ∀𝑦 ∈ suc 𝐴 ¬ 𝑦𝑦)
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4  wo 381   = wceq 1474  wcel 1976  wnfc 2737  wral 2895  suc csuc 5628
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1712  ax-4 1727  ax-5 1826  ax-6 1874  ax-7 1921  ax-8 1978  ax-9 1985  ax-10 2005  ax-11 2020  ax-12 2033  ax-13 2233  ax-ext 2589
This theorem depends on definitions:  df-bi 195  df-or 383  df-an 384  df-tru 1477  df-ex 1695  df-nf 1700  df-sb 1867  df-clab 2596  df-cleq 2602  df-clel 2605  df-nfc 2739  df-ral 2900  df-v 3174  df-un 3544  df-sn 4125  df-suc 5632
This theorem is referenced by:  dfon2lem3  30740
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