Theorem foeq3 5566

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 2241	. . 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 5339	. 2 |- ( F : C -onto-> A <-> ( F Fn C /\ ran F = A ) )
4		df-fo 5339	. 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 4732   Fn wfn 5328   -onto->wfo 5331

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 2213

This theorem depends on definitions:  df-bi 117  df-cleq 2224  df-fo 5339

This theorem is referenced by:  fimadmfo  5577  f1oeq3  5582  foeq123d  5585  resdif  5614  ffoss  5625  fifo  7239  enumct  7374  ctssexmid  7409  exmidfodomrlemr  7473  exmidfodomrlemrALT  7474  qnnen  13132  ctiunctal  13142  unct  13143  quslem  13487  znzrhfo  14744  gausslemma2dlem1f1o  15879  eupthsg  16386  subctctexmid  16722