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Theorem relelfvdm 5128
Description: If a function value has a member, the argument belongs to the domain. (Contributed by Jim Kingdon, 22-Jan-2019.)
Assertion
Ref Expression
relelfvdm ((Rel 𝐹 A (𝐹B)) → B dom 𝐹)

Proof of Theorem relelfvdm
Dummy variables x y are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 elfv 5099 . . . . . 6 (A (𝐹B) ↔ x(A x y(B𝐹yy = x)))
2 exsimpr 1491 . . . . . 6 (x(A x y(B𝐹yy = x)) → xy(B𝐹yy = x))
31, 2sylbi 114 . . . . 5 (A (𝐹B) → xy(B𝐹yy = x))
4 equsb1 1650 . . . . . . . 8 [x / y]y = x
5 spsbbi 1707 . . . . . . . 8 (y(B𝐹yy = x) → ([x / y]B𝐹y ↔ [x / y]y = x))
64, 5mpbiri 157 . . . . . . 7 (y(B𝐹yy = x) → [x / y]B𝐹y)
7 nfv 1402 . . . . . . . 8 y B𝐹x
8 breq2 3740 . . . . . . . 8 (y = x → (B𝐹yB𝐹x))
97, 8sbie 1656 . . . . . . 7 ([x / y]B𝐹yB𝐹x)
106, 9sylib 127 . . . . . 6 (y(B𝐹yy = x) → B𝐹x)
1110eximi 1473 . . . . 5 (xy(B𝐹yy = x) → x B𝐹x)
123, 11syl 14 . . . 4 (A (𝐹B) → x B𝐹x)
1312anim2i 324 . . 3 ((Rel 𝐹 A (𝐹B)) → (Rel 𝐹 x B𝐹x))
14 19.42v 1768 . . 3 (x(Rel 𝐹 B𝐹x) ↔ (Rel 𝐹 x B𝐹x))
1513, 14sylibr 137 . 2 ((Rel 𝐹 A (𝐹B)) → x(Rel 𝐹 B𝐹x))
16 releldm 4494 . . 3 ((Rel 𝐹 B𝐹x) → B dom 𝐹)
1716exlimiv 1471 . 2 (x(Rel 𝐹 B𝐹x) → B dom 𝐹)
1815, 17syl 14 1 ((Rel 𝐹 A (𝐹B)) → B dom 𝐹)
Colors of variables: wff set class
Syntax hints:  wi 4   wa 97  wb 98  wal 1226  wex 1362   wcel 1374  [wsb 1627   class class class wbr 3736  dom cdm 4270  Rel wrel 4275  cfv 4827
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101  ax-io 617  ax-5 1316  ax-7 1317  ax-gen 1318  ax-ie1 1363  ax-ie2 1364  ax-8 1376  ax-10 1377  ax-11 1378  ax-i12 1379  ax-bnd 1380  ax-4 1381  ax-14 1386  ax-17 1400  ax-i9 1404  ax-ial 1409  ax-i5r 1410  ax-ext 2004  ax-sep 3847  ax-pow 3899  ax-pr 3916
This theorem depends on definitions:  df-bi 110  df-3an 875  df-tru 1231  df-nf 1330  df-sb 1628  df-clab 2009  df-cleq 2015  df-clel 2018  df-nfc 2149  df-ral 2287  df-rex 2288  df-v 2535  df-un 2897  df-in 2899  df-ss 2906  df-pw 3334  df-sn 3354  df-pr 3355  df-op 3357  df-uni 3553  df-br 3737  df-opab 3791  df-xp 4276  df-rel 4277  df-dm 4280  df-iota 4792  df-fv 4835
This theorem is referenced by:  elmpt2cl  5619  mpt2xopn0yelv  5774
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