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Theorem fununfun 6597
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 6566 . . 3 (Fun (𝐹𝐺) → Rel (𝐹𝐺))
2 relun 5812 . . 3 (Rel (𝐹𝐺) ↔ (Rel 𝐹 ∧ Rel 𝐺))
31, 2sylib 217 . 2 (Fun (𝐹𝐺) → (Rel 𝐹 ∧ Rel 𝐺))
4 simpl 484 . . . . 5 ((Rel 𝐹 ∧ Rel 𝐺) → Rel 𝐹)
5 fununmo 6596 . . . . . 6 (Fun (𝐹𝐺) → ∃*𝑦 𝑥𝐹𝑦)
65alrimiv 1931 . . . . 5 (Fun (𝐹𝐺) → ∀𝑥∃*𝑦 𝑥𝐹𝑦)
74, 6anim12i 614 . . . 4 (((Rel 𝐹 ∧ Rel 𝐺) ∧ Fun (𝐹𝐺)) → (Rel 𝐹 ∧ ∀𝑥∃*𝑦 𝑥𝐹𝑦))
8 dffun6 6557 . . . 4 (Fun 𝐹 ↔ (Rel 𝐹 ∧ ∀𝑥∃*𝑦 𝑥𝐹𝑦))
97, 8sylibr 233 . . 3 (((Rel 𝐹 ∧ Rel 𝐺) ∧ Fun (𝐹𝐺)) → Fun 𝐹)
10 simpr 486 . . . . 5 ((Rel 𝐹 ∧ Rel 𝐺) → Rel 𝐺)
11 uncom 4154 . . . . . . . 8 (𝐹𝐺) = (𝐺𝐹)
1211funeqi 6570 . . . . . . 7 (Fun (𝐹𝐺) ↔ Fun (𝐺𝐹))
13 fununmo 6596 . . . . . . 7 (Fun (𝐺𝐹) → ∃*𝑦 𝑥𝐺𝑦)
1412, 13sylbi 216 . . . . . 6 (Fun (𝐹𝐺) → ∃*𝑦 𝑥𝐺𝑦)
1514alrimiv 1931 . . . . 5 (Fun (𝐹𝐺) → ∀𝑥∃*𝑦 𝑥𝐺𝑦)
1610, 15anim12i 614 . . . 4 (((Rel 𝐹 ∧ Rel 𝐺) ∧ Fun (𝐹𝐺)) → (Rel 𝐺 ∧ ∀𝑥∃*𝑦 𝑥𝐺𝑦))
17 dffun6 6557 . . . 4 (Fun 𝐺 ↔ (Rel 𝐺 ∧ ∀𝑥∃*𝑦 𝑥𝐺𝑦))
1816, 17sylibr 233 . . 3 (((Rel 𝐹 ∧ Rel 𝐺) ∧ Fun (𝐹𝐺)) → Fun 𝐺)
199, 18jca 513 . 2 (((Rel 𝐹 ∧ Rel 𝐺) ∧ Fun (𝐹𝐺)) → (Fun 𝐹 ∧ Fun 𝐺))
203, 19mpancom 687 1 (Fun (𝐹𝐺) → (Fun 𝐹 ∧ Fun 𝐺))
Colors of variables: wff setvar class
Syntax hints:  wi 4  wa 397  wal 1540  ∃*wmo 2533  cun 3947   class class class wbr 5149  Rel wrel 5682  Fun wfun 6538
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  ax-sep 5300  ax-nul 5307  ax-pr 5428
This theorem depends on definitions:  df-bi 206  df-an 398  df-or 847  df-3an 1090  df-tru 1545  df-fal 1555  df-ex 1783  df-sb 2069  df-mo 2535  df-clab 2711  df-cleq 2725  df-clel 2811  df-ral 3063  df-rex 3072  df-rab 3434  df-v 3477  df-dif 3952  df-un 3954  df-in 3956  df-ss 3966  df-nul 4324  df-if 4530  df-sn 4630  df-pr 4632  df-op 4636  df-br 5150  df-opab 5212  df-id 5575  df-xp 5683  df-rel 5684  df-cnv 5685  df-co 5686  df-fun 6546
This theorem is referenced by:  fsuppunbi  9384
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