Theorem foeq3 5590

Description: Equality theorem for onto functions. (Contributed by NM, 1-Aug-1994.)

Assertion

Ref	Expression
foeq3	|- ( A = B -> ( F : C -onto-> A <-> F : C -onto-> B ) )

Proof of Theorem foeq3

Step	Hyp	Ref	Expression
1		eqeq2 2244	. . 3 |- ( A = B -> ( ran F = A <-> ran F = B ) )
2	1	anbi2d 464	. 2 |- ( A = B -> ( ( F Fn C /\ ran F = A ) <-> ( F Fn C /\ ran F = B ) ) )
3		df-fo 5360	. 2 |- ( F : C -onto-> A <-> ( F Fn C /\ ran F = A ) )
4		df-fo 5360	. 2 |- ( F : C -onto-> B <-> ( F Fn C /\ ran F = B ) )
5	2, 3, 4	3bitr4g 223	1 |- ( A = B -> ( F : C -onto-> A <-> F : C -onto-> B ) )

Syntax hints:   -> wi 4   /\ wa 104   <-> wb 105   = wceq 1398   ran crn 4752   Fn wfn 5349   -onto->wfo 5352

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-5 1496  ax-gen 1498  ax-4 1559  ax-17 1575  ax-ext 2216

This theorem depends on definitions:  df-bi 117  df-cleq 2227  df-fo 5360

This theorem is referenced by:  fimadmfo  5601  f1oeq3  5606  foeq123d  5609  resdif  5638  ffoss  5649  fifo  7269  enumct  7408  ctssexmid  7443  exmidfodomrlemr  7507  exmidfodomrlemrALT  7508  qnnen  13199  ctiunctal  13209  unct  13210  quslem  13554  znzrhfo  14813  gausslemma2dlem1f1o  15950  eupthsg  16457  subctctexmid  16791