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Theorem fununfun 6395
 Description: If the union of classes is a function, the classes itselves are functions. (Contributed by AV, 18-Jul-2019.)
Assertion
Ref Expression
fununfun (Fun (𝐹𝐺) → (Fun 𝐹 ∧ Fun 𝐺))

Proof of Theorem fununfun
Dummy variables 𝑥 𝑦 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 funrel 6365 . . 3 (Fun (𝐹𝐺) → Rel (𝐹𝐺))
2 relun 5677 . . 3 (Rel (𝐹𝐺) ↔ (Rel 𝐹 ∧ Rel 𝐺))
31, 2sylib 220 . 2 (Fun (𝐹𝐺) → (Rel 𝐹 ∧ Rel 𝐺))
4 simpl 485 . . . . 5 ((Rel 𝐹 ∧ Rel 𝐺) → Rel 𝐹)
5 fununmo 6394 . . . . . 6 (Fun (𝐹𝐺) → ∃*𝑦 𝑥𝐹𝑦)
65alrimiv 1922 . . . . 5 (Fun (𝐹𝐺) → ∀𝑥∃*𝑦 𝑥𝐹𝑦)
74, 6anim12i 614 . . . 4 (((Rel 𝐹 ∧ Rel 𝐺) ∧ Fun (𝐹𝐺)) → (Rel 𝐹 ∧ ∀𝑥∃*𝑦 𝑥𝐹𝑦))
8 dffun6 6363 . . . 4 (Fun 𝐹 ↔ (Rel 𝐹 ∧ ∀𝑥∃*𝑦 𝑥𝐹𝑦))
97, 8sylibr 236 . . 3 (((Rel 𝐹 ∧ Rel 𝐺) ∧ Fun (𝐹𝐺)) → Fun 𝐹)
10 simpr 487 . . . . 5 ((Rel 𝐹 ∧ Rel 𝐺) → Rel 𝐺)
11 uncom 4127 . . . . . . . 8 (𝐹𝐺) = (𝐺𝐹)
1211funeqi 6369 . . . . . . 7 (Fun (𝐹𝐺) ↔ Fun (𝐺𝐹))
13 fununmo 6394 . . . . . . 7 (Fun (𝐺𝐹) → ∃*𝑦 𝑥𝐺𝑦)
1412, 13sylbi 219 . . . . . 6 (Fun (𝐹𝐺) → ∃*𝑦 𝑥𝐺𝑦)
1514alrimiv 1922 . . . . 5 (Fun (𝐹𝐺) → ∀𝑥∃*𝑦 𝑥𝐺𝑦)
1610, 15anim12i 614 . . . 4 (((Rel 𝐹 ∧ Rel 𝐺) ∧ Fun (𝐹𝐺)) → (Rel 𝐺 ∧ ∀𝑥∃*𝑦 𝑥𝐺𝑦))
17 dffun6 6363 . . . 4 (Fun 𝐺 ↔ (Rel 𝐺 ∧ ∀𝑥∃*𝑦 𝑥𝐺𝑦))
1816, 17sylibr 236 . . 3 (((Rel 𝐹 ∧ Rel 𝐺) ∧ Fun (𝐹𝐺)) → Fun 𝐺)
199, 18jca 514 . 2 (((Rel 𝐹 ∧ Rel 𝐺) ∧ Fun (𝐹𝐺)) → (Fun 𝐹 ∧ Fun 𝐺))
203, 19mpancom 686 1 (Fun (𝐹𝐺) → (Fun 𝐹 ∧ Fun 𝐺))
 Colors of variables: wff setvar class Syntax hints:   → wi 4   ∧ wa 398  ∀wal 1529  ∃*wmo 2614   ∪ cun 3932   class class class wbr 5057  Rel wrel 5553  Fun wfun 6342 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1790  ax-4 1804  ax-5 1905  ax-6 1964  ax-7 2009  ax-8 2110  ax-9 2118  ax-10 2139  ax-11 2154  ax-12 2170  ax-ext 2791  ax-sep 5194  ax-nul 5201  ax-pr 5320 This theorem depends on definitions:  df-bi 209  df-an 399  df-or 844  df-3an 1084  df-tru 1534  df-ex 1775  df-nf 1779  df-sb 2064  df-mo 2616  df-eu 2648  df-clab 2798  df-cleq 2812  df-clel 2891  df-nfc 2961  df-ral 3141  df-rex 3142  df-rab 3145  df-v 3495  df-dif 3937  df-un 3939  df-in 3941  df-ss 3950  df-nul 4290  df-if 4466  df-sn 4560  df-pr 4562  df-op 4566  df-br 5058  df-opab 5120  df-id 5453  df-xp 5554  df-rel 5555  df-cnv 5556  df-co 5557  df-fun 6350 This theorem is referenced by:  fsuppunbi  8846
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