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Theorem feq3 5133
Description: Equality theorem for functions. (Contributed by NM, 1-Aug-1994.)
Assertion
Ref Expression
feq3 (𝐴 = 𝐵 → (𝐹:𝐶𝐴𝐹:𝐶𝐵))

Proof of Theorem feq3
StepHypRef Expression
1 sseq2 3046 . . 3 (𝐴 = 𝐵 → (ran 𝐹𝐴 ↔ ran 𝐹𝐵))
21anbi2d 452 . 2 (𝐴 = 𝐵 → ((𝐹 Fn 𝐶 ∧ ran 𝐹𝐴) ↔ (𝐹 Fn 𝐶 ∧ ran 𝐹𝐵)))
3 df-f 5006 . 2 (𝐹:𝐶𝐴 ↔ (𝐹 Fn 𝐶 ∧ ran 𝐹𝐴))
4 df-f 5006 . 2 (𝐹:𝐶𝐵 ↔ (𝐹 Fn 𝐶 ∧ ran 𝐹𝐵))
52, 3, 43bitr4g 221 1 (𝐴 = 𝐵 → (𝐹:𝐶𝐴𝐹:𝐶𝐵))
Colors of variables: wff set class
Syntax hints:  wi 4  wa 102  wb 103   = wceq 1289  wss 2997  ran crn 4429   Fn wfn 4997  wf 4998
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-ia2 105  ax-ia3 106  ax-5 1381  ax-7 1382  ax-gen 1383  ax-ie1 1427  ax-ie2 1428  ax-8 1440  ax-11 1442  ax-4 1445  ax-17 1464  ax-i9 1468  ax-ial 1472  ax-i5r 1473  ax-ext 2070
This theorem depends on definitions:  df-bi 115  df-nf 1395  df-sb 1693  df-clab 2075  df-cleq 2081  df-clel 2084  df-in 3003  df-ss 3010  df-f 5006
This theorem is referenced by:  feq23  5134  feq123d  5138  fun2  5169  fconstg  5191  f1eq3  5197  fsng  5454  fsn2  5455  fsnunf  5480  mapvalg  6395  mapsn  6427
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