Theorem php3 8899

Description: Corollary of Pigeonhole Principle. If 𝐴 is finite and 𝐵 is a proper subset of 𝐴, the 𝐵 is strictly less numerous than 𝐴. Stronger version of Corollary 6C of [Enderton] p. 135. (Contributed by NM, 22-Aug-2008.)

Assertion

Ref	Expression
php3	⊢ ((𝐴 ∈ Fin ∧ 𝐵 ⊊ 𝐴) → 𝐵 ≺ 𝐴)

Proof of Theorem php3

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

Step	Hyp	Ref	Expression
1		isfi 8719	. . 3 ⊢ (𝐴 ∈ Fin ↔ ∃𝑥 ∈ ω 𝐴 ≈ 𝑥)
2		relen 8696	. . . . . . . . 9 ⊢ Rel ≈
3	2	brrelex1i 5634	. . . . . . . 8 ⊢ (𝐴 ≈ 𝑥 → 𝐴 ∈ V)
4		pssss 4026	. . . . . . . 8 ⊢ (𝐵 ⊊ 𝐴 → 𝐵 ⊆ 𝐴)
5		ssdomg 8741	. . . . . . . . 9 ⊢ (𝐴 ∈ V → (𝐵 ⊆ 𝐴 → 𝐵 ≼ 𝐴))
6	5	imp 406	. . . . . . . 8 ⊢ ((𝐴 ∈ V ∧ 𝐵 ⊆ 𝐴) → 𝐵 ≼ 𝐴)
7	3, 4, 6	syl2an 595	. . . . . . 7 ⊢ ((𝐴 ≈ 𝑥 ∧ 𝐵 ⊊ 𝐴) → 𝐵 ≼ 𝐴)
8	7	adantll 710	. . . . . 6 ⊢ (((𝑥 ∈ ω ∧ 𝐴 ≈ 𝑥) ∧ 𝐵 ⊊ 𝐴) → 𝐵 ≼ 𝐴)
9		bren 8701	. . . . . . . . 9 ⊢ (𝐴 ≈ 𝑥 ↔ ∃𝑓 𝑓:𝐴–1-1-onto→𝑥)
10		imass2 5999	. . . . . . . . . . . . . . . . 17 ⊢ (𝐵 ⊆ 𝐴 → (𝑓 “ 𝐵) ⊆ (𝑓 “ 𝐴))
11	4, 10	syl 17	. . . . . . . . . . . . . . . 16 ⊢ (𝐵 ⊊ 𝐴 → (𝑓 “ 𝐵) ⊆ (𝑓 “ 𝐴))
12	11	adantl 481	. . . . . . . . . . . . . . 15 ⊢ ((𝑓:𝐴–1-1-onto→𝑥 ∧ 𝐵 ⊊ 𝐴) → (𝑓 “ 𝐵) ⊆ (𝑓 “ 𝐴))
13		pssnel 4401	. . . . . . . . . . . . . . . . 17 ⊢ (𝐵 ⊊ 𝐴 → ∃𝑦(𝑦 ∈ 𝐴 ∧ ¬ 𝑦 ∈ 𝐵))
14		eldif 3893	. . . . . . . . . . . . . . . . . . . 20 ⊢ (𝑦 ∈ (𝐴 ∖ 𝐵) ↔ (𝑦 ∈ 𝐴 ∧ ¬ 𝑦 ∈ 𝐵))
15		f1ofn 6701	. . . . . . . . . . . . . . . . . . . . . . 23 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → 𝑓 Fn 𝐴)
16		difss 4062	. . . . . . . . . . . . . . . . . . . . . . 23 ⊢ (𝐴 ∖ 𝐵) ⊆ 𝐴
17		fnfvima 7091	. . . . . . . . . . . . . . . . . . . . . . . 24 ⊢ ((𝑓 Fn 𝐴 ∧ (𝐴 ∖ 𝐵) ⊆ 𝐴 ∧ 𝑦 ∈ (𝐴 ∖ 𝐵)) → (𝑓‘𝑦) ∈ (𝑓 “ (𝐴 ∖ 𝐵)))
18	17	3expia 1119	. . . . . . . . . . . . . . . . . . . . . . 23 ⊢ ((𝑓 Fn 𝐴 ∧ (𝐴 ∖ 𝐵) ⊆ 𝐴) → (𝑦 ∈ (𝐴 ∖ 𝐵) → (𝑓‘𝑦) ∈ (𝑓 “ (𝐴 ∖ 𝐵))))
19	15, 16, 18	sylancl 585	. . . . . . . . . . . . . . . . . . . . . 22 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → (𝑦 ∈ (𝐴 ∖ 𝐵) → (𝑓‘𝑦) ∈ (𝑓 “ (𝐴 ∖ 𝐵))))
20		dff1o3 6706	. . . . . . . . . . . . . . . . . . . . . . . 24 ⊢ (𝑓:𝐴–1-1-onto→𝑥 ↔ (𝑓:𝐴–onto→𝑥 ∧ Fun ◡𝑓))
21		imadif 6502	. . . . . . . . . . . . . . . . . . . . . . . 24 ⊢ (Fun ◡𝑓 → (𝑓 “ (𝐴 ∖ 𝐵)) = ((𝑓 “ 𝐴) ∖ (𝑓 “ 𝐵)))
22	20, 21	simplbiim 504	. . . . . . . . . . . . . . . . . . . . . . 23 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → (𝑓 “ (𝐴 ∖ 𝐵)) = ((𝑓 “ 𝐴) ∖ (𝑓 “ 𝐵)))
23	22	eleq2d 2824	. . . . . . . . . . . . . . . . . . . . . 22 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → ((𝑓‘𝑦) ∈ (𝑓 “ (𝐴 ∖ 𝐵)) ↔ (𝑓‘𝑦) ∈ ((𝑓 “ 𝐴) ∖ (𝑓 “ 𝐵))))
24	19, 23	sylibd 238	. . . . . . . . . . . . . . . . . . . . 21 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → (𝑦 ∈ (𝐴 ∖ 𝐵) → (𝑓‘𝑦) ∈ ((𝑓 “ 𝐴) ∖ (𝑓 “ 𝐵))))
25		n0i 4264	. . . . . . . . . . . . . . . . . . . . 21 ⊢ ((𝑓‘𝑦) ∈ ((𝑓 “ 𝐴) ∖ (𝑓 “ 𝐵)) → ¬ ((𝑓 “ 𝐴) ∖ (𝑓 “ 𝐵)) = ∅)
26	24, 25	syl6 35	. . . . . . . . . . . . . . . . . . . 20 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → (𝑦 ∈ (𝐴 ∖ 𝐵) → ¬ ((𝑓 “ 𝐴) ∖ (𝑓 “ 𝐵)) = ∅))
27	14, 26	syl5bir 242	. . . . . . . . . . . . . . . . . . 19 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → ((𝑦 ∈ 𝐴 ∧ ¬ 𝑦 ∈ 𝐵) → ¬ ((𝑓 “ 𝐴) ∖ (𝑓 “ 𝐵)) = ∅))
28	27	exlimdv 1937	. . . . . . . . . . . . . . . . . 18 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → (∃𝑦(𝑦 ∈ 𝐴 ∧ ¬ 𝑦 ∈ 𝐵) → ¬ ((𝑓 “ 𝐴) ∖ (𝑓 “ 𝐵)) = ∅))
29	28	imp 406	. . . . . . . . . . . . . . . . 17 ⊢ ((𝑓:𝐴–1-1-onto→𝑥 ∧ ∃𝑦(𝑦 ∈ 𝐴 ∧ ¬ 𝑦 ∈ 𝐵)) → ¬ ((𝑓 “ 𝐴) ∖ (𝑓 “ 𝐵)) = ∅)
30	13, 29	sylan2 592	. . . . . . . . . . . . . . . 16 ⊢ ((𝑓:𝐴–1-1-onto→𝑥 ∧ 𝐵 ⊊ 𝐴) → ¬ ((𝑓 “ 𝐴) ∖ (𝑓 “ 𝐵)) = ∅)
31		ssdif0 4294	. . . . . . . . . . . . . . . 16 ⊢ ((𝑓 “ 𝐴) ⊆ (𝑓 “ 𝐵) ↔ ((𝑓 “ 𝐴) ∖ (𝑓 “ 𝐵)) = ∅)
32	30, 31	sylnibr 328	. . . . . . . . . . . . . . 15 ⊢ ((𝑓:𝐴–1-1-onto→𝑥 ∧ 𝐵 ⊊ 𝐴) → ¬ (𝑓 “ 𝐴) ⊆ (𝑓 “ 𝐵))
33		dfpss3 4017	. . . . . . . . . . . . . . 15 ⊢ ((𝑓 “ 𝐵) ⊊ (𝑓 “ 𝐴) ↔ ((𝑓 “ 𝐵) ⊆ (𝑓 “ 𝐴) ∧ ¬ (𝑓 “ 𝐴) ⊆ (𝑓 “ 𝐵)))
34	12, 32, 33	sylanbrc 582	. . . . . . . . . . . . . 14 ⊢ ((𝑓:𝐴–1-1-onto→𝑥 ∧ 𝐵 ⊊ 𝐴) → (𝑓 “ 𝐵) ⊊ (𝑓 “ 𝐴))
35		imadmrn 5968	. . . . . . . . . . . . . . . . 17 ⊢ (𝑓 “ dom 𝑓) = ran 𝑓
36		f1odm 6704	. . . . . . . . . . . . . . . . . 18 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → dom 𝑓 = 𝐴)
37	36	imaeq2d 5958	. . . . . . . . . . . . . . . . 17 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → (𝑓 “ dom 𝑓) = (𝑓 “ 𝐴))
38		f1ofo 6707	. . . . . . . . . . . . . . . . . 18 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → 𝑓:𝐴–onto→𝑥)
39		forn 6675	. . . . . . . . . . . . . . . . . 18 ⊢ (𝑓:𝐴–onto→𝑥 → ran 𝑓 = 𝑥)
40	38, 39	syl 17	. . . . . . . . . . . . . . . . 17 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → ran 𝑓 = 𝑥)
41	35, 37, 40	3eqtr3a 2803	. . . . . . . . . . . . . . . 16 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → (𝑓 “ 𝐴) = 𝑥)
42	41	psseq2d 4024	. . . . . . . . . . . . . . 15 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → ((𝑓 “ 𝐵) ⊊ (𝑓 “ 𝐴) ↔ (𝑓 “ 𝐵) ⊊ 𝑥))
43	42	adantr 480	. . . . . . . . . . . . . 14 ⊢ ((𝑓:𝐴–1-1-onto→𝑥 ∧ 𝐵 ⊊ 𝐴) → ((𝑓 “ 𝐵) ⊊ (𝑓 “ 𝐴) ↔ (𝑓 “ 𝐵) ⊊ 𝑥))
44	34, 43	mpbid 231	. . . . . . . . . . . . 13 ⊢ ((𝑓:𝐴–1-1-onto→𝑥 ∧ 𝐵 ⊊ 𝐴) → (𝑓 “ 𝐵) ⊊ 𝑥)
45		php 8897	. . . . . . . . . . . . 13 ⊢ ((𝑥 ∈ ω ∧ (𝑓 “ 𝐵) ⊊ 𝑥) → ¬ 𝑥 ≈ (𝑓 “ 𝐵))
46	44, 45	sylan2 592	. . . . . . . . . . . 12 ⊢ ((𝑥 ∈ ω ∧ (𝑓:𝐴–1-1-onto→𝑥 ∧ 𝐵 ⊊ 𝐴)) → ¬ 𝑥 ≈ (𝑓 “ 𝐵))
47		f1of1 6699	. . . . . . . . . . . . . . . 16 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → 𝑓:𝐴–1-1→𝑥)
48		f1ores 6714	. . . . . . . . . . . . . . . 16 ⊢ ((𝑓:𝐴–1-1→𝑥 ∧ 𝐵 ⊆ 𝐴) → (𝑓 ↾ 𝐵):𝐵–1-1-onto→(𝑓 “ 𝐵))
49	47, 4, 48	syl2an 595	. . . . . . . . . . . . . . 15 ⊢ ((𝑓:𝐴–1-1-onto→𝑥 ∧ 𝐵 ⊊ 𝐴) → (𝑓 ↾ 𝐵):𝐵–1-1-onto→(𝑓 “ 𝐵))
50		vex 3426	. . . . . . . . . . . . . . . . . 18 ⊢ 𝑓 ∈ V
51	50	resex 5928	. . . . . . . . . . . . . . . . 17 ⊢ (𝑓 ↾ 𝐵) ∈ V
52		f1oeq1 6688	. . . . . . . . . . . . . . . . 17 ⊢ (𝑦 = (𝑓 ↾ 𝐵) → (𝑦:𝐵–1-1-onto→(𝑓 “ 𝐵) ↔ (𝑓 ↾ 𝐵):𝐵–1-1-onto→(𝑓 “ 𝐵)))
53	51, 52	spcev 3535	. . . . . . . . . . . . . . . 16 ⊢ ((𝑓 ↾ 𝐵):𝐵–1-1-onto→(𝑓 “ 𝐵) → ∃𝑦 𝑦:𝐵–1-1-onto→(𝑓 “ 𝐵))
54		bren 8701	. . . . . . . . . . . . . . . 16 ⊢ (𝐵 ≈ (𝑓 “ 𝐵) ↔ ∃𝑦 𝑦:𝐵–1-1-onto→(𝑓 “ 𝐵))
55	53, 54	sylibr 233	. . . . . . . . . . . . . . 15 ⊢ ((𝑓 ↾ 𝐵):𝐵–1-1-onto→(𝑓 “ 𝐵) → 𝐵 ≈ (𝑓 “ 𝐵))
56	49, 55	syl 17	. . . . . . . . . . . . . 14 ⊢ ((𝑓:𝐴–1-1-onto→𝑥 ∧ 𝐵 ⊊ 𝐴) → 𝐵 ≈ (𝑓 “ 𝐵))
57		entr 8747	. . . . . . . . . . . . . . 15 ⊢ ((𝑥 ≈ 𝐵 ∧ 𝐵 ≈ (𝑓 “ 𝐵)) → 𝑥 ≈ (𝑓 “ 𝐵))
58	57	expcom 413	. . . . . . . . . . . . . 14 ⊢ (𝐵 ≈ (𝑓 “ 𝐵) → (𝑥 ≈ 𝐵 → 𝑥 ≈ (𝑓 “ 𝐵)))
59	56, 58	syl 17	. . . . . . . . . . . . 13 ⊢ ((𝑓:𝐴–1-1-onto→𝑥 ∧ 𝐵 ⊊ 𝐴) → (𝑥 ≈ 𝐵 → 𝑥 ≈ (𝑓 “ 𝐵)))
60	59	adantl 481	. . . . . . . . . . . 12 ⊢ ((𝑥 ∈ ω ∧ (𝑓:𝐴–1-1-onto→𝑥 ∧ 𝐵 ⊊ 𝐴)) → (𝑥 ≈ 𝐵 → 𝑥 ≈ (𝑓 “ 𝐵)))
61	46, 60	mtod 197	. . . . . . . . . . 11 ⊢ ((𝑥 ∈ ω ∧ (𝑓:𝐴–1-1-onto→𝑥 ∧ 𝐵 ⊊ 𝐴)) → ¬ 𝑥 ≈ 𝐵)
62	61	exp32 420	. . . . . . . . . 10 ⊢ (𝑥 ∈ ω → (𝑓:𝐴–1-1-onto→𝑥 → (𝐵 ⊊ 𝐴 → ¬ 𝑥 ≈ 𝐵)))
63	62	exlimdv 1937	. . . . . . . . 9 ⊢ (𝑥 ∈ ω → (∃𝑓 𝑓:𝐴–1-1-onto→𝑥 → (𝐵 ⊊ 𝐴 → ¬ 𝑥 ≈ 𝐵)))
64	9, 63	syl5bi 241	. . . . . . . 8 ⊢ (𝑥 ∈ ω → (𝐴 ≈ 𝑥 → (𝐵 ⊊ 𝐴 → ¬ 𝑥 ≈ 𝐵)))
65	64	imp31 417	. . . . . . 7 ⊢ (((𝑥 ∈ ω ∧ 𝐴 ≈ 𝑥) ∧ 𝐵 ⊊ 𝐴) → ¬ 𝑥 ≈ 𝐵)
66		entr 8747	. . . . . . . . . 10 ⊢ ((𝐵 ≈ 𝐴 ∧ 𝐴 ≈ 𝑥) → 𝐵 ≈ 𝑥)
67	66	ex 412	. . . . . . . . 9 ⊢ (𝐵 ≈ 𝐴 → (𝐴 ≈ 𝑥 → 𝐵 ≈ 𝑥))
68		ensym 8744	. . . . . . . . 9 ⊢ (𝐵 ≈ 𝑥 → 𝑥 ≈ 𝐵)
69	67, 68	syl6com 37	. . . . . . . 8 ⊢ (𝐴 ≈ 𝑥 → (𝐵 ≈ 𝐴 → 𝑥 ≈ 𝐵))
70	69	ad2antlr 723	. . . . . . 7 ⊢ (((𝑥 ∈ ω ∧ 𝐴 ≈ 𝑥) ∧ 𝐵 ⊊ 𝐴) → (𝐵 ≈ 𝐴 → 𝑥 ≈ 𝐵))
71	65, 70	mtod 197	. . . . . 6 ⊢ (((𝑥 ∈ ω ∧ 𝐴 ≈ 𝑥) ∧ 𝐵 ⊊ 𝐴) → ¬ 𝐵 ≈ 𝐴)
72		brsdom 8718	. . . . . 6 ⊢ (𝐵 ≺ 𝐴 ↔ (𝐵 ≼ 𝐴 ∧ ¬ 𝐵 ≈ 𝐴))
73	8, 71, 72	sylanbrc 582	. . . . 5 ⊢ (((𝑥 ∈ ω ∧ 𝐴 ≈ 𝑥) ∧ 𝐵 ⊊ 𝐴) → 𝐵 ≺ 𝐴)
74	73	exp31 419	. . . 4 ⊢ (𝑥 ∈ ω → (𝐴 ≈ 𝑥 → (𝐵 ⊊ 𝐴 → 𝐵 ≺ 𝐴)))
75	74	rexlimiv 3208	. . 3 ⊢ (∃𝑥 ∈ ω 𝐴 ≈ 𝑥 → (𝐵 ⊊ 𝐴 → 𝐵 ≺ 𝐴))
76	1, 75	sylbi 216	. 2 ⊢ (𝐴 ∈ Fin → (𝐵 ⊊ 𝐴 → 𝐵 ≺ 𝐴))
77	76	imp 406	1 ⊢ ((𝐴 ∈ Fin ∧ 𝐵 ⊊ 𝐴) → 𝐵 ≺ 𝐴)

Syntax hints:  ¬ wn 3   → wi 4   ↔ wb 205   ∧ wa 395   = wceq 1539  ∃wex 1783   ∈ wcel 2108  ∃wrex 3064  Vcvv 3422   ∖ cdif 3880   ⊆ wss 3883   ⊊ wpss 3884  ∅c0 4253   class class class wbr 5070  ^◡ccnv 5579  dom cdm 5580  ran crn 5581   ↾ cres 5582   “ cima 5583  Fun wfun 6412   Fn wfn 6413  –1-1→wf1 6415  –onto→wfo 6416  –1-1-onto→wf1o 6417  ‘cfv 6418  ωcom 7687   ≈ cen 8688   ≼ cdom 8689   ≺ csdm 8690  Fincfn 8691

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1799  ax-4 1813  ax-5 1914  ax-6 1972  ax-7 2012  ax-8 2110  ax-9 2118  ax-10 2139  ax-11 2156  ax-12 2173  ax-ext 2709  ax-sep 5218  ax-nul 5225  ax-pow 5283  ax-pr 5347  ax-un 7566

This theorem depends on definitions:  df-bi 206  df-an 396  df-or 844  df-3or 1086  df-3an 1087  df-tru 1542  df-fal 1552  df-ex 1784  df-nf 1788  df-sb 2069  df-mo 2540  df-eu 2569  df-clab 2716  df-cleq 2730  df-clel 2817  df-nfc 2888  df-ne 2943  df-ral 3068  df-rex 3069  df-rab 3072  df-v 3424  df-dif 3886  df-un 3888  df-in 3890  df-ss 3900  df-pss 3902  df-nul 4254  df-if 4457  df-pw 4532  df-sn 4559  df-pr 4561  df-tp 4563  df-op 4565  df-uni 4837  df-br 5071  df-opab 5133  df-tr 5188  df-id 5480  df-eprel 5486  df-po 5494  df-so 5495  df-fr 5535  df-we 5537  df-xp 5586  df-rel 5587  df-cnv 5588  df-co 5589  df-dm 5590  df-rn 5591  df-res 5592  df-ima 5593  df-ord 6254  df-on 6255  df-lim 6256  df-suc 6257  df-iota 6376  df-fun 6420  df-fn 6421  df-f 6422  df-f1 6423  df-fo 6424  df-f1o 6425  df-fv 6426  df-om 7688  df-er 8456  df-en 8692  df-dom 8693  df-sdom 8694  df-fin 8695

This theorem is referenced by:  phpeqd  8902  pssinf  8962  f1finf1o  8975  findcard3  8987  fofinf1o  9024  ackbij1b  9926  fincssdom  10010  fin23lem25  10011  canthp1lem2  10340  pwfseqlem4  10349  uzindi  13630  symggen  18993  pgpssslw  19134  pgpfaclem2  19600  ppiltx  26231  finminlem  34434  lindsenlbs  35699