Theorem foeq3 5557

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 5332	. 2 |- ( F : C -onto-> A <-> ( F Fn C /\ ran F = A ) )
4		df-fo 5332	. 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 1397   ran crn 4726   Fn wfn 5321   -onto->wfo 5324

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 1495  ax-gen 1497  ax-4 1558  ax-17 1574  ax-ext 2213

This theorem depends on definitions:  df-bi 117  df-cleq 2224  df-fo 5332

This theorem is referenced by:  fimadmfo  5568  f1oeq3  5573  foeq123d  5576  resdif  5605  ffoss  5616  fifo  7179  enumct  7314  ctssexmid  7349  exmidfodomrlemr  7413  exmidfodomrlemrALT  7414  qnnen  13070  ctiunctal  13080  unct  13081  quslem  13425  znzrhfo  14681  gausslemma2dlem1f1o  15808  eupthsg  16315  subctctexmid  16652