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Theorem fnun 5960
 Description: The union of two functions with disjoint domains. (Contributed by NM, 22-Sep-2004.)
Assertion
Ref Expression
fnun (((𝐹 Fn 𝐴𝐺 Fn 𝐵) ∧ (𝐴𝐵) = ∅) → (𝐹𝐺) Fn (𝐴𝐵))

Proof of Theorem fnun
StepHypRef Expression
1 df-fn 5855 . . 3 (𝐹 Fn 𝐴 ↔ (Fun 𝐹 ∧ dom 𝐹 = 𝐴))
2 df-fn 5855 . . 3 (𝐺 Fn 𝐵 ↔ (Fun 𝐺 ∧ dom 𝐺 = 𝐵))
3 ineq12 3792 . . . . . . . . . . 11 ((dom 𝐹 = 𝐴 ∧ dom 𝐺 = 𝐵) → (dom 𝐹 ∩ dom 𝐺) = (𝐴𝐵))
43eqeq1d 2623 . . . . . . . . . 10 ((dom 𝐹 = 𝐴 ∧ dom 𝐺 = 𝐵) → ((dom 𝐹 ∩ dom 𝐺) = ∅ ↔ (𝐴𝐵) = ∅))
54anbi2d 739 . . . . . . . . 9 ((dom 𝐹 = 𝐴 ∧ dom 𝐺 = 𝐵) → (((Fun 𝐹 ∧ Fun 𝐺) ∧ (dom 𝐹 ∩ dom 𝐺) = ∅) ↔ ((Fun 𝐹 ∧ Fun 𝐺) ∧ (𝐴𝐵) = ∅)))
6 funun 5895 . . . . . . . . 9 (((Fun 𝐹 ∧ Fun 𝐺) ∧ (dom 𝐹 ∩ dom 𝐺) = ∅) → Fun (𝐹𝐺))
75, 6syl6bir 244 . . . . . . . 8 ((dom 𝐹 = 𝐴 ∧ dom 𝐺 = 𝐵) → (((Fun 𝐹 ∧ Fun 𝐺) ∧ (𝐴𝐵) = ∅) → Fun (𝐹𝐺)))
8 dmun 5296 . . . . . . . . 9 dom (𝐹𝐺) = (dom 𝐹 ∪ dom 𝐺)
9 uneq12 3745 . . . . . . . . 9 ((dom 𝐹 = 𝐴 ∧ dom 𝐺 = 𝐵) → (dom 𝐹 ∪ dom 𝐺) = (𝐴𝐵))
108, 9syl5eq 2667 . . . . . . . 8 ((dom 𝐹 = 𝐴 ∧ dom 𝐺 = 𝐵) → dom (𝐹𝐺) = (𝐴𝐵))
117, 10jctird 566 . . . . . . 7 ((dom 𝐹 = 𝐴 ∧ dom 𝐺 = 𝐵) → (((Fun 𝐹 ∧ Fun 𝐺) ∧ (𝐴𝐵) = ∅) → (Fun (𝐹𝐺) ∧ dom (𝐹𝐺) = (𝐴𝐵))))
12 df-fn 5855 . . . . . . 7 ((𝐹𝐺) Fn (𝐴𝐵) ↔ (Fun (𝐹𝐺) ∧ dom (𝐹𝐺) = (𝐴𝐵)))
1311, 12syl6ibr 242 . . . . . 6 ((dom 𝐹 = 𝐴 ∧ dom 𝐺 = 𝐵) → (((Fun 𝐹 ∧ Fun 𝐺) ∧ (𝐴𝐵) = ∅) → (𝐹𝐺) Fn (𝐴𝐵)))
1413expd 452 . . . . 5 ((dom 𝐹 = 𝐴 ∧ dom 𝐺 = 𝐵) → ((Fun 𝐹 ∧ Fun 𝐺) → ((𝐴𝐵) = ∅ → (𝐹𝐺) Fn (𝐴𝐵))))
1514impcom 446 . . . 4 (((Fun 𝐹 ∧ Fun 𝐺) ∧ (dom 𝐹 = 𝐴 ∧ dom 𝐺 = 𝐵)) → ((𝐴𝐵) = ∅ → (𝐹𝐺) Fn (𝐴𝐵)))
1615an4s 868 . . 3 (((Fun 𝐹 ∧ dom 𝐹 = 𝐴) ∧ (Fun 𝐺 ∧ dom 𝐺 = 𝐵)) → ((𝐴𝐵) = ∅ → (𝐹𝐺) Fn (𝐴𝐵)))
171, 2, 16syl2anb 496 . 2 ((𝐹 Fn 𝐴𝐺 Fn 𝐵) → ((𝐴𝐵) = ∅ → (𝐹𝐺) Fn (𝐴𝐵)))
1817imp 445 1 (((𝐹 Fn 𝐴𝐺 Fn 𝐵) ∧ (𝐴𝐵) = ∅) → (𝐹𝐺) Fn (𝐴𝐵))
 Colors of variables: wff setvar class Syntax hints:   → wi 4   ∧ wa 384   = wceq 1480   ∪ cun 3557   ∩ cin 3558  ∅c0 3896  dom cdm 5079  Fun wfun 5846   Fn wfn 5847 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1719  ax-4 1734  ax-5 1836  ax-6 1885  ax-7 1932  ax-9 1996  ax-10 2016  ax-11 2031  ax-12 2044  ax-13 2245  ax-ext 2601  ax-sep 4746  ax-nul 4754  ax-pr 4872 This theorem depends on definitions:  df-bi 197  df-or 385  df-an 386  df-3an 1038  df-tru 1483  df-ex 1702  df-nf 1707  df-sb 1878  df-eu 2473  df-mo 2474  df-clab 2608  df-cleq 2614  df-clel 2617  df-nfc 2750  df-ral 2912  df-rab 2916  df-v 3191  df-dif 3562  df-un 3564  df-in 3566  df-ss 3573  df-nul 3897  df-if 4064  df-sn 4154  df-pr 4156  df-op 4160  df-br 4619  df-opab 4679  df-id 4994  df-rel 5086  df-cnv 5087  df-co 5088  df-dm 5089  df-fun 5854  df-fn 5855 This theorem is referenced by:  fnunsn  5961  fun  6028  foun  6117  f1oun  6118  undifixp  7896  brwdom2  8430  sseqfn  30257  bnj927  30582  bnj535  30703  fullfunfnv  31730  finixpnum  33061  poimirlem1  33077  poimirlem2  33078  poimirlem3  33079  poimirlem4  33080  poimirlem6  33082  poimirlem7  33083  poimirlem11  33087  poimirlem12  33088  poimirlem16  33092  poimirlem17  33093  poimirlem19  33095  poimirlem20  33096
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