Theorem foeq2 5267

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

Assertion

Ref	Expression
foeq2	⊢ (A = B → (F:A–onto→C ↔ F:B–onto→C))

Proof of Theorem foeq2

Step	Hyp	Ref	Expression
1		fneq2 5175	. . 3 ⊢ (A = B → (F Fn A ↔ F Fn B))
2	1	anbi1d 685	. 2 ⊢ (A = B → ((F Fn A ∧ ran F = C) ↔ (F Fn B ∧ ran F = C)))
3		df-fo 4794	. 2 ⊢ (F:A–onto→C ↔ (F Fn A ∧ ran F = C))
4		df-fo 4794	. 2 ⊢ (F:B–onto→C ↔ (F Fn B ∧ ran F = C))
5	2, 3, 4	3bitr4g 279	1 ⊢ (A = B → (F:A–onto→C ↔ F:B–onto→C))

This proof depends on syntax axioms:   → wi 4   ↔ wb 176   ∧ wa 358   = wceq 1642  ran crn 4774   Fn wfn 4777  –onto→wfo 4780

This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1546  ax-5 1557  ax-17 1616  ax-9 1654  ax-8 1675  ax-11 1746  ax-ext 2334

This proof depends on definitions:  df-bi 177  df-an 360  df-ex 1542  df-cleq 2346  df-fn 4791  df-fo 4794

This theorem is used by:  f1oeq2  5283