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Theorem infval 8433
Description: Alternate expression for the infimum. (Contributed by AV, 2-Sep-2020.)
Hypothesis
Ref Expression
infexd.1 (𝜑𝑅 Or 𝐴)
Assertion
Ref Expression
infval (𝜑 → inf(𝐵, 𝐴, 𝑅) = (𝑥𝐴 (∀𝑦𝐵 ¬ 𝑦𝑅𝑥 ∧ ∀𝑦𝐴 (𝑥𝑅𝑦 → ∃𝑧𝐵 𝑧𝑅𝑦))))
Distinct variable groups:   𝑦,𝐴,𝑧   𝑦,𝐵,𝑧   𝑦,𝑅,𝑧   𝑥,𝐴   𝑥,𝐵   𝑥,𝑅   𝜑,𝑥,𝑦,𝑧

Proof of Theorem infval
StepHypRef Expression
1 df-inf 8390 . 2 inf(𝐵, 𝐴, 𝑅) = sup(𝐵, 𝐴, 𝑅)
2 infexd.1 . . . . 5 (𝜑𝑅 Or 𝐴)
3 cnvso 5712 . . . . 5 (𝑅 Or 𝐴𝑅 Or 𝐴)
42, 3sylib 208 . . . 4 (𝜑𝑅 Or 𝐴)
54supval2 8402 . . 3 (𝜑 → sup(𝐵, 𝐴, 𝑅) = (𝑥𝐴 (∀𝑦𝐵 ¬ 𝑥𝑅𝑦 ∧ ∀𝑦𝐴 (𝑦𝑅𝑥 → ∃𝑧𝐵 𝑦𝑅𝑧))))
6 vex 3234 . . . . . . . . 9 𝑥 ∈ V
7 vex 3234 . . . . . . . . 9 𝑦 ∈ V
86, 7brcnv 5337 . . . . . . . 8 (𝑥𝑅𝑦𝑦𝑅𝑥)
98a1i 11 . . . . . . 7 (𝜑 → (𝑥𝑅𝑦𝑦𝑅𝑥))
109notbid 307 . . . . . 6 (𝜑 → (¬ 𝑥𝑅𝑦 ↔ ¬ 𝑦𝑅𝑥))
1110ralbidv 3015 . . . . 5 (𝜑 → (∀𝑦𝐵 ¬ 𝑥𝑅𝑦 ↔ ∀𝑦𝐵 ¬ 𝑦𝑅𝑥))
127, 6brcnv 5337 . . . . . . . 8 (𝑦𝑅𝑥𝑥𝑅𝑦)
1312a1i 11 . . . . . . 7 (𝜑 → (𝑦𝑅𝑥𝑥𝑅𝑦))
14 vex 3234 . . . . . . . . . 10 𝑧 ∈ V
157, 14brcnv 5337 . . . . . . . . 9 (𝑦𝑅𝑧𝑧𝑅𝑦)
1615a1i 11 . . . . . . . 8 (𝜑 → (𝑦𝑅𝑧𝑧𝑅𝑦))
1716rexbidv 3081 . . . . . . 7 (𝜑 → (∃𝑧𝐵 𝑦𝑅𝑧 ↔ ∃𝑧𝐵 𝑧𝑅𝑦))
1813, 17imbi12d 333 . . . . . 6 (𝜑 → ((𝑦𝑅𝑥 → ∃𝑧𝐵 𝑦𝑅𝑧) ↔ (𝑥𝑅𝑦 → ∃𝑧𝐵 𝑧𝑅𝑦)))
1918ralbidv 3015 . . . . 5 (𝜑 → (∀𝑦𝐴 (𝑦𝑅𝑥 → ∃𝑧𝐵 𝑦𝑅𝑧) ↔ ∀𝑦𝐴 (𝑥𝑅𝑦 → ∃𝑧𝐵 𝑧𝑅𝑦)))
2011, 19anbi12d 747 . . . 4 (𝜑 → ((∀𝑦𝐵 ¬ 𝑥𝑅𝑦 ∧ ∀𝑦𝐴 (𝑦𝑅𝑥 → ∃𝑧𝐵 𝑦𝑅𝑧)) ↔ (∀𝑦𝐵 ¬ 𝑦𝑅𝑥 ∧ ∀𝑦𝐴 (𝑥𝑅𝑦 → ∃𝑧𝐵 𝑧𝑅𝑦))))
2120riotabidv 6653 . . 3 (𝜑 → (𝑥𝐴 (∀𝑦𝐵 ¬ 𝑥𝑅𝑦 ∧ ∀𝑦𝐴 (𝑦𝑅𝑥 → ∃𝑧𝐵 𝑦𝑅𝑧))) = (𝑥𝐴 (∀𝑦𝐵 ¬ 𝑦𝑅𝑥 ∧ ∀𝑦𝐴 (𝑥𝑅𝑦 → ∃𝑧𝐵 𝑧𝑅𝑦))))
225, 21eqtrd 2685 . 2 (𝜑 → sup(𝐵, 𝐴, 𝑅) = (𝑥𝐴 (∀𝑦𝐵 ¬ 𝑦𝑅𝑥 ∧ ∀𝑦𝐴 (𝑥𝑅𝑦 → ∃𝑧𝐵 𝑧𝑅𝑦))))
231, 22syl5eq 2697 1 (𝜑 → inf(𝐵, 𝐴, 𝑅) = (𝑥𝐴 (∀𝑦𝐵 ¬ 𝑦𝑅𝑥 ∧ ∀𝑦𝐴 (𝑥𝑅𝑦 → ∃𝑧𝐵 𝑧𝑅𝑦))))
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wi 4  wb 196  wa 383   = wceq 1523  wral 2941  wrex 2942   class class class wbr 4685   Or wor 5063  ccnv 5142  crio 6650  supcsup 8387  infcinf 8388
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1762  ax-4 1777  ax-5 1879  ax-6 1945  ax-7 1981  ax-9 2039  ax-10 2059  ax-11 2074  ax-12 2087  ax-13 2282  ax-ext 2631  ax-sep 4814  ax-nul 4822  ax-pr 4936
This theorem depends on definitions:  df-bi 197  df-or 384  df-an 385  df-3or 1055  df-3an 1056  df-tru 1526  df-ex 1745  df-nf 1750  df-sb 1938  df-eu 2502  df-mo 2503  df-clab 2638  df-cleq 2644  df-clel 2647  df-nfc 2782  df-ne 2824  df-ral 2946  df-rex 2947  df-reu 2948  df-rmo 2949  df-rab 2950  df-v 3233  df-sbc 3469  df-dif 3610  df-un 3612  df-in 3614  df-ss 3621  df-nul 3949  df-if 4120  df-sn 4211  df-pr 4213  df-op 4217  df-uni 4469  df-br 4686  df-opab 4746  df-po 5064  df-so 5065  df-cnv 5151  df-iota 5889  df-riota 6651  df-sup 8389  df-inf 8390
This theorem is referenced by: (None)
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