Theorem f1ss 6319

Description: A function that is one-to-one is also one-to-one on some superset of its codomain. (Contributed by Mario Carneiro, 12-Jan-2013.)

Assertion

Ref	Expression
f1ss	⊢ ((𝐹:𝐴–1-1→𝐵 ∧ 𝐵 ⊆ 𝐶) → 𝐹:𝐴–1-1→𝐶)

Proof of Theorem f1ss

Step	Hyp	Ref	Expression
1		f1f 6314	. . 3 ⊢ (𝐹:𝐴–1-1→𝐵 → 𝐹:𝐴⟶𝐵)
2		fss 6267	. . 3 ⊢ ((𝐹:𝐴⟶𝐵 ∧ 𝐵 ⊆ 𝐶) → 𝐹:𝐴⟶𝐶)
3	1, 2	sylan 576	. 2 ⊢ ((𝐹:𝐴–1-1→𝐵 ∧ 𝐵 ⊆ 𝐶) → 𝐹:𝐴⟶𝐶)
4		df-f1 6104	. . . 4 ⊢ (𝐹:𝐴–1-1→𝐵 ↔ (𝐹:𝐴⟶𝐵 ∧ Fun ◡𝐹))
5	4	simprbi 491	. . 3 ⊢ (𝐹:𝐴–1-1→𝐵 → Fun ◡𝐹)
6	5	adantr 473	. 2 ⊢ ((𝐹:𝐴–1-1→𝐵 ∧ 𝐵 ⊆ 𝐶) → Fun ◡𝐹)
7		df-f1 6104	. 2 ⊢ (𝐹:𝐴–1-1→𝐶 ↔ (𝐹:𝐴⟶𝐶 ∧ Fun ◡𝐹))
8	3, 6, 7	sylanbrc 579	1 ⊢ ((𝐹:𝐴–1-1→𝐵 ∧ 𝐵 ⊆ 𝐶) → 𝐹:𝐴–1-1→𝐶)

Syntax hints:   → wi 4   ∧ wa 385   ⊆ wss 3767  ^◡ccnv 5309  Fun wfun 6093  ⟶wf 6095  –1-1→wf1 6096

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1891  ax-4 1905  ax-5 2006  ax-6 2072  ax-7 2107  ax-9 2166  ax-10 2185  ax-11 2200  ax-12 2213  ax-ext 2775

This theorem depends on definitions:  df-bi 199  df-an 386  df-or 875  df-tru 1657  df-ex 1876  df-nf 1880  df-sb 2065  df-clab 2784  df-cleq 2790  df-clel 2793  df-in 3774  df-ss 3781  df-f 6103  df-f1 6104

This theorem is referenced by:  f1sng  6395  f1prex  6765  domssex2  8360  1sdom  8403  marypha1lem  8579  marypha2  8585  isinffi  9102  fseqenlem1  9131  dfac12r  9254  ackbij2  9351  cff1  9366  fin23lem28  9448  fin23lem41  9460  pwfseqlem5  9771  hashf1lem1  13484  gsumzres  18622  gsumzcl2  18623  gsumzf1o  18625  gsumzaddlem  18633  gsumzmhm  18649  gsumzoppg  18656  lindfres  20484  islindf3  20487  dvne0f1  24113  istrkg2ld  25708  ausgrusgrb  26393  uspgrushgr  26403  usgruspgr  26406  uspgr1e  26470  sizusglecusglem1  26703  qqhre  30572  erdsze2lem1  31694  eldioph2lem2  38098  eldioph2  38099