Theorem feq23i 5477

Description: Equality inference for functions. (Contributed by Paul Chapman, 22-Jun-2011.)

Hypotheses

Ref	Expression
feq23i.1	|- A = C
feq23i.2	|- B = D

Assertion

Ref	Expression
feq23i	|- ( F : A --> B <-> F : C --> D )

Proof of Theorem feq23i

Step	Hyp	Ref	Expression
1		feq23i.1	. 2 |- A = C
2		feq23i.2	. 2 |- B = D
3		feq23 5468	. 2 |- ( ( A = C /\ B = D ) -> ( F : A --> B <-> F : C --> D ) )
4	1, 2, 3	mp2an 426	1 |- ( F : A --> B <-> F : C --> D )

Syntax hints:   <-> wb 105   = wceq 1397   -->wf 5322

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-7 1496  ax-gen 1497  ax-ie1 1541  ax-ie2 1542  ax-8 1552  ax-11 1554  ax-4 1558  ax-17 1574  ax-i9 1578  ax-ial 1582  ax-i5r 1583  ax-ext 2213

This theorem depends on definitions:  df-bi 117  df-nf 1509  df-sb 1811  df-clab 2218  df-cleq 2224  df-clel 2227  df-in 3206  df-ss 3213  df-fn 5329  df-f 5330

This theorem is referenced by:  ftpg  5837  uhgr0  15935  lfgredg2dom  15982