Theorem fodomfi 8239

Description: An onto function implies dominance of domain over range, for finite sets. Unlike fodom 9344 for arbitrary sets, this theorem does not require the Axiom of Choice for its proof. (Contributed by NM, 23-Mar-2006.) (Proof shortened by Mario Carneiro, 16-Nov-2014.)

Assertion

Ref	Expression
fodomfi	⊢ ((𝐴 ∈ Fin ∧ 𝐹:𝐴–onto→𝐵) → 𝐵 ≼ 𝐴)

Proof of Theorem fodomfi

Dummy variables 𝑥 𝑦 𝑧 are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		foima 6120	. . 3 ⊢ (𝐹:𝐴–onto→𝐵 → (𝐹 “ 𝐴) = 𝐵)
2	1	adantl 482	. 2 ⊢ ((𝐴 ∈ Fin ∧ 𝐹:𝐴–onto→𝐵) → (𝐹 “ 𝐴) = 𝐵)
3		fofn 6117	. . . 4 ⊢ (𝐹:𝐴–onto→𝐵 → 𝐹 Fn 𝐴)
4		imaeq2 5462	. . . . . . . 8 ⊢ (𝑥 = ∅ → (𝐹 “ 𝑥) = (𝐹 “ ∅))
5		ima0 5481	. . . . . . . 8 ⊢ (𝐹 “ ∅) = ∅
6	4, 5	syl6eq 2672	. . . . . . 7 ⊢ (𝑥 = ∅ → (𝐹 “ 𝑥) = ∅)
7		id 22	. . . . . . 7 ⊢ (𝑥 = ∅ → 𝑥 = ∅)
8	6, 7	breq12d 4666	. . . . . 6 ⊢ (𝑥 = ∅ → ((𝐹 “ 𝑥) ≼ 𝑥 ↔ ∅ ≼ ∅))
9	8	imbi2d 330	. . . . 5 ⊢ (𝑥 = ∅ → ((𝐹 Fn 𝐴 → (𝐹 “ 𝑥) ≼ 𝑥) ↔ (𝐹 Fn 𝐴 → ∅ ≼ ∅)))
10		imaeq2 5462	. . . . . . 7 ⊢ (𝑥 = 𝑦 → (𝐹 “ 𝑥) = (𝐹 “ 𝑦))
11		id 22	. . . . . . 7 ⊢ (𝑥 = 𝑦 → 𝑥 = 𝑦)
12	10, 11	breq12d 4666	. . . . . 6 ⊢ (𝑥 = 𝑦 → ((𝐹 “ 𝑥) ≼ 𝑥 ↔ (𝐹 “ 𝑦) ≼ 𝑦))
13	12	imbi2d 330	. . . . 5 ⊢ (𝑥 = 𝑦 → ((𝐹 Fn 𝐴 → (𝐹 “ 𝑥) ≼ 𝑥) ↔ (𝐹 Fn 𝐴 → (𝐹 “ 𝑦) ≼ 𝑦)))
14		imaeq2 5462	. . . . . . 7 ⊢ (𝑥 = (𝑦 ∪ {𝑧}) → (𝐹 “ 𝑥) = (𝐹 “ (𝑦 ∪ {𝑧})))
15		id 22	. . . . . . 7 ⊢ (𝑥 = (𝑦 ∪ {𝑧}) → 𝑥 = (𝑦 ∪ {𝑧}))
16	14, 15	breq12d 4666	. . . . . 6 ⊢ (𝑥 = (𝑦 ∪ {𝑧}) → ((𝐹 “ 𝑥) ≼ 𝑥 ↔ (𝐹 “ (𝑦 ∪ {𝑧})) ≼ (𝑦 ∪ {𝑧})))
17	16	imbi2d 330	. . . . 5 ⊢ (𝑥 = (𝑦 ∪ {𝑧}) → ((𝐹 Fn 𝐴 → (𝐹 “ 𝑥) ≼ 𝑥) ↔ (𝐹 Fn 𝐴 → (𝐹 “ (𝑦 ∪ {𝑧})) ≼ (𝑦 ∪ {𝑧}))))
18		imaeq2 5462	. . . . . . 7 ⊢ (𝑥 = 𝐴 → (𝐹 “ 𝑥) = (𝐹 “ 𝐴))
19		id 22	. . . . . . 7 ⊢ (𝑥 = 𝐴 → 𝑥 = 𝐴)
20	18, 19	breq12d 4666	. . . . . 6 ⊢ (𝑥 = 𝐴 → ((𝐹 “ 𝑥) ≼ 𝑥 ↔ (𝐹 “ 𝐴) ≼ 𝐴))
21	20	imbi2d 330	. . . . 5 ⊢ (𝑥 = 𝐴 → ((𝐹 Fn 𝐴 → (𝐹 “ 𝑥) ≼ 𝑥) ↔ (𝐹 Fn 𝐴 → (𝐹 “ 𝐴) ≼ 𝐴)))
22		0ex 4790	. . . . . . 7 ⊢ ∅ ∈ V
23	22	0dom 8090	. . . . . 6 ⊢ ∅ ≼ ∅
24	23	a1i 11	. . . . 5 ⊢ (𝐹 Fn 𝐴 → ∅ ≼ ∅)
25		fnfun 5988	. . . . . . . . . . . . . . 15 ⊢ (𝐹 Fn 𝐴 → Fun 𝐹)
26	25	ad2antrl 764	. . . . . . . . . . . . . 14 ⊢ (((𝑦 ∈ Fin ∧ ¬ 𝑧 ∈ 𝑦) ∧ (𝐹 Fn 𝐴 ∧ (𝐹 “ 𝑦) ≼ 𝑦)) → Fun 𝐹)
27		funressn 6426	. . . . . . . . . . . . . 14 ⊢ (Fun 𝐹 → (𝐹 ↾ {𝑧}) ⊆ {⟨𝑧, (𝐹‘𝑧)⟩})
28		rnss 5354	. . . . . . . . . . . . . 14 ⊢ ((𝐹 ↾ {𝑧}) ⊆ {⟨𝑧, (𝐹‘𝑧)⟩} → ran (𝐹 ↾ {𝑧}) ⊆ ran {⟨𝑧, (𝐹‘𝑧)⟩})
29	26, 27, 28	3syl 18	. . . . . . . . . . . . 13 ⊢ (((𝑦 ∈ Fin ∧ ¬ 𝑧 ∈ 𝑦) ∧ (𝐹 Fn 𝐴 ∧ (𝐹 “ 𝑦) ≼ 𝑦)) → ran (𝐹 ↾ {𝑧}) ⊆ ran {⟨𝑧, (𝐹‘𝑧)⟩})
30		df-ima 5127	. . . . . . . . . . . . 13 ⊢ (𝐹 “ {𝑧}) = ran (𝐹 ↾ {𝑧})
31		vex 3203	. . . . . . . . . . . . . . 15 ⊢ 𝑧 ∈ V
32	31	rnsnop 5616	. . . . . . . . . . . . . 14 ⊢ ran {⟨𝑧, (𝐹‘𝑧)⟩} = {(𝐹‘𝑧)}
33	32	eqcomi 2631	. . . . . . . . . . . . 13 ⊢ {(𝐹‘𝑧)} = ran {⟨𝑧, (𝐹‘𝑧)⟩}
34	29, 30, 33	3sstr4g 3646	. . . . . . . . . . . 12 ⊢ (((𝑦 ∈ Fin ∧ ¬ 𝑧 ∈ 𝑦) ∧ (𝐹 Fn 𝐴 ∧ (𝐹 “ 𝑦) ≼ 𝑦)) → (𝐹 “ {𝑧}) ⊆ {(𝐹‘𝑧)})
35		snex 4908	. . . . . . . . . . . 12 ⊢ {(𝐹‘𝑧)} ∈ V
36		ssexg 4804	. . . . . . . . . . . 12 ⊢ (((𝐹 “ {𝑧}) ⊆ {(𝐹‘𝑧)} ∧ {(𝐹‘𝑧)} ∈ V) → (𝐹 “ {𝑧}) ∈ V)
37	34, 35, 36	sylancl 694	. . . . . . . . . . 11 ⊢ (((𝑦 ∈ Fin ∧ ¬ 𝑧 ∈ 𝑦) ∧ (𝐹 Fn 𝐴 ∧ (𝐹 “ 𝑦) ≼ 𝑦)) → (𝐹 “ {𝑧}) ∈ V)
38		fvi 6255	. . . . . . . . . . 11 ⊢ ((𝐹 “ {𝑧}) ∈ V → ( I ‘(𝐹 “ {𝑧})) = (𝐹 “ {𝑧}))
39	37, 38	syl 17	. . . . . . . . . 10 ⊢ (((𝑦 ∈ Fin ∧ ¬ 𝑧 ∈ 𝑦) ∧ (𝐹 Fn 𝐴 ∧ (𝐹 “ 𝑦) ≼ 𝑦)) → ( I ‘(𝐹 “ {𝑧})) = (𝐹 “ {𝑧}))
40	39	uneq2d 3767	. . . . . . . . 9 ⊢ (((𝑦 ∈ Fin ∧ ¬ 𝑧 ∈ 𝑦) ∧ (𝐹 Fn 𝐴 ∧ (𝐹 “ 𝑦) ≼ 𝑦)) → ((𝐹 “ 𝑦) ∪ ( I ‘(𝐹 “ {𝑧}))) = ((𝐹 “ 𝑦) ∪ (𝐹 “ {𝑧})))
41		imaundi 5545	. . . . . . . . 9 ⊢ (𝐹 “ (𝑦 ∪ {𝑧})) = ((𝐹 “ 𝑦) ∪ (𝐹 “ {𝑧}))
42	40, 41	syl6eqr 2674	. . . . . . . 8 ⊢ (((𝑦 ∈ Fin ∧ ¬ 𝑧 ∈ 𝑦) ∧ (𝐹 Fn 𝐴 ∧ (𝐹 “ 𝑦) ≼ 𝑦)) → ((𝐹 “ 𝑦) ∪ ( I ‘(𝐹 “ {𝑧}))) = (𝐹 “ (𝑦 ∪ {𝑧})))
43		simprr 796	. . . . . . . . 9 ⊢ (((𝑦 ∈ Fin ∧ ¬ 𝑧 ∈ 𝑦) ∧ (𝐹 Fn 𝐴 ∧ (𝐹 “ 𝑦) ≼ 𝑦)) → (𝐹 “ 𝑦) ≼ 𝑦)
44		ssdomg 8001	. . . . . . . . . . . 12 ⊢ ({(𝐹‘𝑧)} ∈ V → ((𝐹 “ {𝑧}) ⊆ {(𝐹‘𝑧)} → (𝐹 “ {𝑧}) ≼ {(𝐹‘𝑧)}))
45	35, 34, 44	mpsyl 68	. . . . . . . . . . 11 ⊢ (((𝑦 ∈ Fin ∧ ¬ 𝑧 ∈ 𝑦) ∧ (𝐹 Fn 𝐴 ∧ (𝐹 “ 𝑦) ≼ 𝑦)) → (𝐹 “ {𝑧}) ≼ {(𝐹‘𝑧)})
46		fvex 6201	. . . . . . . . . . . . 13 ⊢ (𝐹‘𝑧) ∈ V
47	46	ensn1 8020	. . . . . . . . . . . 12 ⊢ {(𝐹‘𝑧)} ≈ 1𝑜
48	31	ensn1 8020	. . . . . . . . . . . 12 ⊢ {𝑧} ≈ 1𝑜
49	47, 48	entr4i 8013	. . . . . . . . . . 11 ⊢ {(𝐹‘𝑧)} ≈ {𝑧}
50		domentr 8015	. . . . . . . . . . 11 ⊢ (((𝐹 “ {𝑧}) ≼ {(𝐹‘𝑧)} ∧ {(𝐹‘𝑧)} ≈ {𝑧}) → (𝐹 “ {𝑧}) ≼ {𝑧})
51	45, 49, 50	sylancl 694	. . . . . . . . . 10 ⊢ (((𝑦 ∈ Fin ∧ ¬ 𝑧 ∈ 𝑦) ∧ (𝐹 Fn 𝐴 ∧ (𝐹 “ 𝑦) ≼ 𝑦)) → (𝐹 “ {𝑧}) ≼ {𝑧})
52	39, 51	eqbrtrd 4675	. . . . . . . . 9 ⊢ (((𝑦 ∈ Fin ∧ ¬ 𝑧 ∈ 𝑦) ∧ (𝐹 Fn 𝐴 ∧ (𝐹 “ 𝑦) ≼ 𝑦)) → ( I ‘(𝐹 “ {𝑧})) ≼ {𝑧})
53		simplr 792	. . . . . . . . . 10 ⊢ (((𝑦 ∈ Fin ∧ ¬ 𝑧 ∈ 𝑦) ∧ (𝐹 Fn 𝐴 ∧ (𝐹 “ 𝑦) ≼ 𝑦)) → ¬ 𝑧 ∈ 𝑦)
54		disjsn 4246	. . . . . . . . . 10 ⊢ ((𝑦 ∩ {𝑧}) = ∅ ↔ ¬ 𝑧 ∈ 𝑦)
55	53, 54	sylibr 224	. . . . . . . . 9 ⊢ (((𝑦 ∈ Fin ∧ ¬ 𝑧 ∈ 𝑦) ∧ (𝐹 Fn 𝐴 ∧ (𝐹 “ 𝑦) ≼ 𝑦)) → (𝑦 ∩ {𝑧}) = ∅)
56		undom 8048	. . . . . . . . 9 ⊢ ((((𝐹 “ 𝑦) ≼ 𝑦 ∧ ( I ‘(𝐹 “ {𝑧})) ≼ {𝑧}) ∧ (𝑦 ∩ {𝑧}) = ∅) → ((𝐹 “ 𝑦) ∪ ( I ‘(𝐹 “ {𝑧}))) ≼ (𝑦 ∪ {𝑧}))
57	43, 52, 55, 56	syl21anc 1325	. . . . . . . 8 ⊢ (((𝑦 ∈ Fin ∧ ¬ 𝑧 ∈ 𝑦) ∧ (𝐹 Fn 𝐴 ∧ (𝐹 “ 𝑦) ≼ 𝑦)) → ((𝐹 “ 𝑦) ∪ ( I ‘(𝐹 “ {𝑧}))) ≼ (𝑦 ∪ {𝑧}))
58	42, 57	eqbrtrrd 4677	. . . . . . 7 ⊢ (((𝑦 ∈ Fin ∧ ¬ 𝑧 ∈ 𝑦) ∧ (𝐹 Fn 𝐴 ∧ (𝐹 “ 𝑦) ≼ 𝑦)) → (𝐹 “ (𝑦 ∪ {𝑧})) ≼ (𝑦 ∪ {𝑧}))
59	58	exp32 631	. . . . . 6 ⊢ ((𝑦 ∈ Fin ∧ ¬ 𝑧 ∈ 𝑦) → (𝐹 Fn 𝐴 → ((𝐹 “ 𝑦) ≼ 𝑦 → (𝐹 “ (𝑦 ∪ {𝑧})) ≼ (𝑦 ∪ {𝑧}))))
60	59	a2d 29	. . . . 5 ⊢ ((𝑦 ∈ Fin ∧ ¬ 𝑧 ∈ 𝑦) → ((𝐹 Fn 𝐴 → (𝐹 “ 𝑦) ≼ 𝑦) → (𝐹 Fn 𝐴 → (𝐹 “ (𝑦 ∪ {𝑧})) ≼ (𝑦 ∪ {𝑧}))))
61	9, 13, 17, 21, 24, 60	findcard2s 8201	. . . 4 ⊢ (𝐴 ∈ Fin → (𝐹 Fn 𝐴 → (𝐹 “ 𝐴) ≼ 𝐴))
62	3, 61	syl5 34	. . 3 ⊢ (𝐴 ∈ Fin → (𝐹:𝐴–onto→𝐵 → (𝐹 “ 𝐴) ≼ 𝐴))
63	62	imp 445	. 2 ⊢ ((𝐴 ∈ Fin ∧ 𝐹:𝐴–onto→𝐵) → (𝐹 “ 𝐴) ≼ 𝐴)
64	2, 63	eqbrtrrd 4677	1 ⊢ ((𝐴 ∈ Fin ∧ 𝐹:𝐴–onto→𝐵) → 𝐵 ≼ 𝐴)

Syntax hints:  ¬ wn 3   → wi 4   ∧ wa 384   = wceq 1483   ∈ wcel 1990  Vcvv 3200   ∪ cun 3572   ∩ cin 3573   ⊆ wss 3574  ∅c0 3915  {csn 4177  ⟨cop 4183   class class class wbr 4653   I cid 5023  ran crn 5115   ↾ cres 5116   “ cima 5117  Fun wfun 5882   Fn wfn 5883  –onto→wfo 5886  ‘cfv 5888  1_𝑜c1o 7553   ≈ cen 7952   ≼ cdom 7953  Fincfn 7955

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1722  ax-4 1737  ax-5 1839  ax-6 1888  ax-7 1935  ax-8 1992  ax-9 1999  ax-10 2019  ax-11 2034  ax-12 2047  ax-13 2246  ax-ext 2602  ax-sep 4781  ax-nul 4789  ax-pow 4843  ax-pr 4906  ax-un 6949

This theorem depends on definitions:  df-bi 197  df-or 385  df-an 386  df-3or 1038  df-3an 1039  df-tru 1486  df-ex 1705  df-nf 1710  df-sb 1881  df-eu 2474  df-mo 2475  df-clab 2609  df-cleq 2615  df-clel 2618  df-nfc 2753  df-ne 2795  df-ral 2917  df-rex 2918  df-reu 2919  df-rab 2921  df-v 3202  df-sbc 3436  df-dif 3577  df-un 3579  df-in 3581  df-ss 3588  df-pss 3590  df-nul 3916  df-if 4087  df-pw 4160  df-sn 4178  df-pr 4180  df-tp 4182  df-op 4184  df-uni 4437  df-br 4654  df-opab 4713  df-tr 4753  df-id 5024  df-eprel 5029  df-po 5035  df-so 5036  df-fr 5073  df-we 5075  df-xp 5120  df-rel 5121  df-cnv 5122  df-co 5123  df-dm 5124  df-rn 5125  df-res 5126  df-ima 5127  df-ord 5726  df-on 5727  df-lim 5728  df-suc 5729  df-iota 5851  df-fun 5890  df-fn 5891  df-f 5892  df-f1 5893  df-fo 5894  df-f1o 5895  df-fv 5896  df-om 7066  df-1o 7560  df-er 7742  df-en 7956  df-dom 7957  df-fin 7959

This theorem is referenced by:  fodomfib  8240  fofinf1o  8241  fidomdm  8243  fofi  8252  pwfilem  8260  cmpsub  21203  alexsubALT  21855  phpreu  33393  poimirlem26  33435