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Theorem friOLD 5638
Description: Obsolete version of fri 5637 as of 16-Nov-2024. (Contributed by NM, 18-Mar-1997.) (Proof modification is discouraged.) (New usage is discouraged.)
Assertion
Ref Expression
friOLD (((𝐵𝐶𝑅 Fr 𝐴) ∧ (𝐵𝐴𝐵 ≠ ∅)) → ∃𝑥𝐵𝑦𝐵 ¬ 𝑦𝑅𝑥)
Distinct variable groups:   𝑥,𝑦,𝐴   𝑥,𝐵,𝑦   𝑥,𝑅,𝑦
Allowed substitution hints:   𝐶(𝑥,𝑦)

Proof of Theorem friOLD
Dummy variable 𝑧 is distinct from all other variables.
StepHypRef Expression
1 df-fr 5632 . . 3 (𝑅 Fr 𝐴 ↔ ∀𝑧((𝑧𝐴𝑧 ≠ ∅) → ∃𝑥𝑧𝑦𝑧 ¬ 𝑦𝑅𝑥))
2 sseq1 4008 . . . . . 6 (𝑧 = 𝐵 → (𝑧𝐴𝐵𝐴))
3 neeq1 3004 . . . . . 6 (𝑧 = 𝐵 → (𝑧 ≠ ∅ ↔ 𝐵 ≠ ∅))
42, 3anbi12d 632 . . . . 5 (𝑧 = 𝐵 → ((𝑧𝐴𝑧 ≠ ∅) ↔ (𝐵𝐴𝐵 ≠ ∅)))
5 raleq 3323 . . . . . 6 (𝑧 = 𝐵 → (∀𝑦𝑧 ¬ 𝑦𝑅𝑥 ↔ ∀𝑦𝐵 ¬ 𝑦𝑅𝑥))
65rexeqbi1dv 3335 . . . . 5 (𝑧 = 𝐵 → (∃𝑥𝑧𝑦𝑧 ¬ 𝑦𝑅𝑥 ↔ ∃𝑥𝐵𝑦𝐵 ¬ 𝑦𝑅𝑥))
74, 6imbi12d 345 . . . 4 (𝑧 = 𝐵 → (((𝑧𝐴𝑧 ≠ ∅) → ∃𝑥𝑧𝑦𝑧 ¬ 𝑦𝑅𝑥) ↔ ((𝐵𝐴𝐵 ≠ ∅) → ∃𝑥𝐵𝑦𝐵 ¬ 𝑦𝑅𝑥)))
87spcgv 3587 . . 3 (𝐵𝐶 → (∀𝑧((𝑧𝐴𝑧 ≠ ∅) → ∃𝑥𝑧𝑦𝑧 ¬ 𝑦𝑅𝑥) → ((𝐵𝐴𝐵 ≠ ∅) → ∃𝑥𝐵𝑦𝐵 ¬ 𝑦𝑅𝑥)))
91, 8biimtrid 241 . 2 (𝐵𝐶 → (𝑅 Fr 𝐴 → ((𝐵𝐴𝐵 ≠ ∅) → ∃𝑥𝐵𝑦𝐵 ¬ 𝑦𝑅𝑥)))
109imp31 419 1 (((𝐵𝐶𝑅 Fr 𝐴) ∧ (𝐵𝐴𝐵 ≠ ∅)) → ∃𝑥𝐵𝑦𝐵 ¬ 𝑦𝑅𝑥)
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4  wa 397  wal 1540   = wceq 1542  wcel 2107  wne 2941  wral 3062  wrex 3071  wss 3949  c0 4323   class class class wbr 5149   Fr wfr 5629
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1798  ax-4 1812  ax-5 1914  ax-6 1972  ax-7 2012  ax-8 2109  ax-9 2117  ax-ext 2704
This theorem depends on definitions:  df-bi 206  df-an 398  df-tru 1545  df-ex 1783  df-sb 2069  df-clab 2711  df-cleq 2725  df-clel 2811  df-ne 2942  df-ral 3063  df-rex 3072  df-v 3477  df-in 3956  df-ss 3966  df-fr 5632
This theorem is referenced by: (None)
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