Theorem php3 8146

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 7979	. . 3 ⊢ (𝐴 ∈ Fin ↔ ∃𝑥 ∈ ω 𝐴 ≈ 𝑥)
2		relen 7960	. . . . . . . . 9 ⊢ Rel ≈
3	2	brrelexi 5158	. . . . . . . 8 ⊢ (𝐴 ≈ 𝑥 → 𝐴 ∈ V)
4		pssss 3702	. . . . . . . 8 ⊢ (𝐵 ⊊ 𝐴 → 𝐵 ⊆ 𝐴)
5		ssdomg 8001	. . . . . . . . 9 ⊢ (𝐴 ∈ V → (𝐵 ⊆ 𝐴 → 𝐵 ≼ 𝐴))
6	5	imp 445	. . . . . . . 8 ⊢ ((𝐴 ∈ V ∧ 𝐵 ⊆ 𝐴) → 𝐵 ≼ 𝐴)
7	3, 4, 6	syl2an 494	. . . . . . 7 ⊢ ((𝐴 ≈ 𝑥 ∧ 𝐵 ⊊ 𝐴) → 𝐵 ≼ 𝐴)
8	7	adantll 750	. . . . . 6 ⊢ (((𝑥 ∈ ω ∧ 𝐴 ≈ 𝑥) ∧ 𝐵 ⊊ 𝐴) → 𝐵 ≼ 𝐴)
9		bren 7964	. . . . . . . . 9 ⊢ (𝐴 ≈ 𝑥 ↔ ∃𝑓 𝑓:𝐴–1-1-onto→𝑥)
10		imass2 5501	. . . . . . . . . . . . . . . . 17 ⊢ (𝐵 ⊆ 𝐴 → (𝑓 “ 𝐵) ⊆ (𝑓 “ 𝐴))
11	4, 10	syl 17	. . . . . . . . . . . . . . . 16 ⊢ (𝐵 ⊊ 𝐴 → (𝑓 “ 𝐵) ⊆ (𝑓 “ 𝐴))
12	11	adantl 482	. . . . . . . . . . . . . . 15 ⊢ ((𝑓:𝐴–1-1-onto→𝑥 ∧ 𝐵 ⊊ 𝐴) → (𝑓 “ 𝐵) ⊆ (𝑓 “ 𝐴))
13		pssnel 4039	. . . . . . . . . . . . . . . . 17 ⊢ (𝐵 ⊊ 𝐴 → ∃𝑦(𝑦 ∈ 𝐴 ∧ ¬ 𝑦 ∈ 𝐵))
14		eldif 3584	. . . . . . . . . . . . . . . . . . . 20 ⊢ (𝑦 ∈ (𝐴 ∖ 𝐵) ↔ (𝑦 ∈ 𝐴 ∧ ¬ 𝑦 ∈ 𝐵))
15		f1ofn 6138	. . . . . . . . . . . . . . . . . . . . . . 23 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → 𝑓 Fn 𝐴)
16		difss 3737	. . . . . . . . . . . . . . . . . . . . . . 23 ⊢ (𝐴 ∖ 𝐵) ⊆ 𝐴
17		fnfvima 6496	. . . . . . . . . . . . . . . . . . . . . . . 24 ⊢ ((𝑓 Fn 𝐴 ∧ (𝐴 ∖ 𝐵) ⊆ 𝐴 ∧ 𝑦 ∈ (𝐴 ∖ 𝐵)) → (𝑓‘𝑦) ∈ (𝑓 “ (𝐴 ∖ 𝐵)))
18	17	3expia 1267	. . . . . . . . . . . . . . . . . . . . . . 23 ⊢ ((𝑓 Fn 𝐴 ∧ (𝐴 ∖ 𝐵) ⊆ 𝐴) → (𝑦 ∈ (𝐴 ∖ 𝐵) → (𝑓‘𝑦) ∈ (𝑓 “ (𝐴 ∖ 𝐵))))
19	15, 16, 18	sylancl 694	. . . . . . . . . . . . . . . . . . . . . 22 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → (𝑦 ∈ (𝐴 ∖ 𝐵) → (𝑓‘𝑦) ∈ (𝑓 “ (𝐴 ∖ 𝐵))))
20		dff1o3 6143	. . . . . . . . . . . . . . . . . . . . . . . . 25 ⊢ (𝑓:𝐴–1-1-onto→𝑥 ↔ (𝑓:𝐴–onto→𝑥 ∧ Fun ◡𝑓))
21	20	simprbi 480	. . . . . . . . . . . . . . . . . . . . . . . 24 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → Fun ◡𝑓)
22		imadif 5973	. . . . . . . . . . . . . . . . . . . . . . . 24 ⊢ (Fun ◡𝑓 → (𝑓 “ (𝐴 ∖ 𝐵)) = ((𝑓 “ 𝐴) ∖ (𝑓 “ 𝐵)))
23	21, 22	syl 17	. . . . . . . . . . . . . . . . . . . . . . 23 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → (𝑓 “ (𝐴 ∖ 𝐵)) = ((𝑓 “ 𝐴) ∖ (𝑓 “ 𝐵)))
24	23	eleq2d 2687	. . . . . . . . . . . . . . . . . . . . . 22 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → ((𝑓‘𝑦) ∈ (𝑓 “ (𝐴 ∖ 𝐵)) ↔ (𝑓‘𝑦) ∈ ((𝑓 “ 𝐴) ∖ (𝑓 “ 𝐵))))
25	19, 24	sylibd 229	. . . . . . . . . . . . . . . . . . . . 21 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → (𝑦 ∈ (𝐴 ∖ 𝐵) → (𝑓‘𝑦) ∈ ((𝑓 “ 𝐴) ∖ (𝑓 “ 𝐵))))
26		n0i 3920	. . . . . . . . . . . . . . . . . . . . 21 ⊢ ((𝑓‘𝑦) ∈ ((𝑓 “ 𝐴) ∖ (𝑓 “ 𝐵)) → ¬ ((𝑓 “ 𝐴) ∖ (𝑓 “ 𝐵)) = ∅)
27	25, 26	syl6 35	. . . . . . . . . . . . . . . . . . . 20 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → (𝑦 ∈ (𝐴 ∖ 𝐵) → ¬ ((𝑓 “ 𝐴) ∖ (𝑓 “ 𝐵)) = ∅))
28	14, 27	syl5bir 233	. . . . . . . . . . . . . . . . . . 19 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → ((𝑦 ∈ 𝐴 ∧ ¬ 𝑦 ∈ 𝐵) → ¬ ((𝑓 “ 𝐴) ∖ (𝑓 “ 𝐵)) = ∅))
29	28	exlimdv 1861	. . . . . . . . . . . . . . . . . 18 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → (∃𝑦(𝑦 ∈ 𝐴 ∧ ¬ 𝑦 ∈ 𝐵) → ¬ ((𝑓 “ 𝐴) ∖ (𝑓 “ 𝐵)) = ∅))
30	29	imp 445	. . . . . . . . . . . . . . . . 17 ⊢ ((𝑓:𝐴–1-1-onto→𝑥 ∧ ∃𝑦(𝑦 ∈ 𝐴 ∧ ¬ 𝑦 ∈ 𝐵)) → ¬ ((𝑓 “ 𝐴) ∖ (𝑓 “ 𝐵)) = ∅)
31	13, 30	sylan2 491	. . . . . . . . . . . . . . . 16 ⊢ ((𝑓:𝐴–1-1-onto→𝑥 ∧ 𝐵 ⊊ 𝐴) → ¬ ((𝑓 “ 𝐴) ∖ (𝑓 “ 𝐵)) = ∅)
32		ssdif0 3942	. . . . . . . . . . . . . . . 16 ⊢ ((𝑓 “ 𝐴) ⊆ (𝑓 “ 𝐵) ↔ ((𝑓 “ 𝐴) ∖ (𝑓 “ 𝐵)) = ∅)
33	31, 32	sylnibr 319	. . . . . . . . . . . . . . 15 ⊢ ((𝑓:𝐴–1-1-onto→𝑥 ∧ 𝐵 ⊊ 𝐴) → ¬ (𝑓 “ 𝐴) ⊆ (𝑓 “ 𝐵))
34		dfpss3 3693	. . . . . . . . . . . . . . 15 ⊢ ((𝑓 “ 𝐵) ⊊ (𝑓 “ 𝐴) ↔ ((𝑓 “ 𝐵) ⊆ (𝑓 “ 𝐴) ∧ ¬ (𝑓 “ 𝐴) ⊆ (𝑓 “ 𝐵)))
35	12, 33, 34	sylanbrc 698	. . . . . . . . . . . . . 14 ⊢ ((𝑓:𝐴–1-1-onto→𝑥 ∧ 𝐵 ⊊ 𝐴) → (𝑓 “ 𝐵) ⊊ (𝑓 “ 𝐴))
36		imadmrn 5476	. . . . . . . . . . . . . . . . 17 ⊢ (𝑓 “ dom 𝑓) = ran 𝑓
37		f1odm 6141	. . . . . . . . . . . . . . . . . 18 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → dom 𝑓 = 𝐴)
38	37	imaeq2d 5466	. . . . . . . . . . . . . . . . 17 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → (𝑓 “ dom 𝑓) = (𝑓 “ 𝐴))
39		f1ofo 6144	. . . . . . . . . . . . . . . . . 18 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → 𝑓:𝐴–onto→𝑥)
40		forn 6118	. . . . . . . . . . . . . . . . . 18 ⊢ (𝑓:𝐴–onto→𝑥 → ran 𝑓 = 𝑥)
41	39, 40	syl 17	. . . . . . . . . . . . . . . . 17 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → ran 𝑓 = 𝑥)
42	36, 38, 41	3eqtr3a 2680	. . . . . . . . . . . . . . . 16 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → (𝑓 “ 𝐴) = 𝑥)
43	42	psseq2d 3700	. . . . . . . . . . . . . . 15 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → ((𝑓 “ 𝐵) ⊊ (𝑓 “ 𝐴) ↔ (𝑓 “ 𝐵) ⊊ 𝑥))
44	43	adantr 481	. . . . . . . . . . . . . 14 ⊢ ((𝑓:𝐴–1-1-onto→𝑥 ∧ 𝐵 ⊊ 𝐴) → ((𝑓 “ 𝐵) ⊊ (𝑓 “ 𝐴) ↔ (𝑓 “ 𝐵) ⊊ 𝑥))
45	35, 44	mpbid 222	. . . . . . . . . . . . 13 ⊢ ((𝑓:𝐴–1-1-onto→𝑥 ∧ 𝐵 ⊊ 𝐴) → (𝑓 “ 𝐵) ⊊ 𝑥)
46		php 8144	. . . . . . . . . . . . 13 ⊢ ((𝑥 ∈ ω ∧ (𝑓 “ 𝐵) ⊊ 𝑥) → ¬ 𝑥 ≈ (𝑓 “ 𝐵))
47	45, 46	sylan2 491	. . . . . . . . . . . 12 ⊢ ((𝑥 ∈ ω ∧ (𝑓:𝐴–1-1-onto→𝑥 ∧ 𝐵 ⊊ 𝐴)) → ¬ 𝑥 ≈ (𝑓 “ 𝐵))
48		f1of1 6136	. . . . . . . . . . . . . . . 16 ⊢ (𝑓:𝐴–1-1-onto→𝑥 → 𝑓:𝐴–1-1→𝑥)
49		f1ores 6151	. . . . . . . . . . . . . . . 16 ⊢ ((𝑓:𝐴–1-1→𝑥 ∧ 𝐵 ⊆ 𝐴) → (𝑓 ↾ 𝐵):𝐵–1-1-onto→(𝑓 “ 𝐵))
50	48, 4, 49	syl2an 494	. . . . . . . . . . . . . . 15 ⊢ ((𝑓:𝐴–1-1-onto→𝑥 ∧ 𝐵 ⊊ 𝐴) → (𝑓 ↾ 𝐵):𝐵–1-1-onto→(𝑓 “ 𝐵))
51		vex 3203	. . . . . . . . . . . . . . . . . 18 ⊢ 𝑓 ∈ V
52	51	resex 5443	. . . . . . . . . . . . . . . . 17 ⊢ (𝑓 ↾ 𝐵) ∈ V
53		f1oeq1 6127	. . . . . . . . . . . . . . . . 17 ⊢ (𝑦 = (𝑓 ↾ 𝐵) → (𝑦:𝐵–1-1-onto→(𝑓 “ 𝐵) ↔ (𝑓 ↾ 𝐵):𝐵–1-1-onto→(𝑓 “ 𝐵)))
54	52, 53	spcev 3300	. . . . . . . . . . . . . . . 16 ⊢ ((𝑓 ↾ 𝐵):𝐵–1-1-onto→(𝑓 “ 𝐵) → ∃𝑦 𝑦:𝐵–1-1-onto→(𝑓 “ 𝐵))
55		bren 7964	. . . . . . . . . . . . . . . 16 ⊢ (𝐵 ≈ (𝑓 “ 𝐵) ↔ ∃𝑦 𝑦:𝐵–1-1-onto→(𝑓 “ 𝐵))
56	54, 55	sylibr 224	. . . . . . . . . . . . . . 15 ⊢ ((𝑓 ↾ 𝐵):𝐵–1-1-onto→(𝑓 “ 𝐵) → 𝐵 ≈ (𝑓 “ 𝐵))
57	50, 56	syl 17	. . . . . . . . . . . . . 14 ⊢ ((𝑓:𝐴–1-1-onto→𝑥 ∧ 𝐵 ⊊ 𝐴) → 𝐵 ≈ (𝑓 “ 𝐵))
58		entr 8008	. . . . . . . . . . . . . . 15 ⊢ ((𝑥 ≈ 𝐵 ∧ 𝐵 ≈ (𝑓 “ 𝐵)) → 𝑥 ≈ (𝑓 “ 𝐵))
59	58	expcom 451	. . . . . . . . . . . . . 14 ⊢ (𝐵 ≈ (𝑓 “ 𝐵) → (𝑥 ≈ 𝐵 → 𝑥 ≈ (𝑓 “ 𝐵)))
60	57, 59	syl 17	. . . . . . . . . . . . 13 ⊢ ((𝑓:𝐴–1-1-onto→𝑥 ∧ 𝐵 ⊊ 𝐴) → (𝑥 ≈ 𝐵 → 𝑥 ≈ (𝑓 “ 𝐵)))
61	60	adantl 482	. . . . . . . . . . . 12 ⊢ ((𝑥 ∈ ω ∧ (𝑓:𝐴–1-1-onto→𝑥 ∧ 𝐵 ⊊ 𝐴)) → (𝑥 ≈ 𝐵 → 𝑥 ≈ (𝑓 “ 𝐵)))
62	47, 61	mtod 189	. . . . . . . . . . 11 ⊢ ((𝑥 ∈ ω ∧ (𝑓:𝐴–1-1-onto→𝑥 ∧ 𝐵 ⊊ 𝐴)) → ¬ 𝑥 ≈ 𝐵)
63	62	exp32 631	. . . . . . . . . 10 ⊢ (𝑥 ∈ ω → (𝑓:𝐴–1-1-onto→𝑥 → (𝐵 ⊊ 𝐴 → ¬ 𝑥 ≈ 𝐵)))
64	63	exlimdv 1861	. . . . . . . . 9 ⊢ (𝑥 ∈ ω → (∃𝑓 𝑓:𝐴–1-1-onto→𝑥 → (𝐵 ⊊ 𝐴 → ¬ 𝑥 ≈ 𝐵)))
65	9, 64	syl5bi 232	. . . . . . . 8 ⊢ (𝑥 ∈ ω → (𝐴 ≈ 𝑥 → (𝐵 ⊊ 𝐴 → ¬ 𝑥 ≈ 𝐵)))
66	65	imp31 448	. . . . . . 7 ⊢ (((𝑥 ∈ ω ∧ 𝐴 ≈ 𝑥) ∧ 𝐵 ⊊ 𝐴) → ¬ 𝑥 ≈ 𝐵)
67		entr 8008	. . . . . . . . . 10 ⊢ ((𝐵 ≈ 𝐴 ∧ 𝐴 ≈ 𝑥) → 𝐵 ≈ 𝑥)
68	67	ex 450	. . . . . . . . 9 ⊢ (𝐵 ≈ 𝐴 → (𝐴 ≈ 𝑥 → 𝐵 ≈ 𝑥))
69		ensym 8005	. . . . . . . . 9 ⊢ (𝐵 ≈ 𝑥 → 𝑥 ≈ 𝐵)
70	68, 69	syl6com 37	. . . . . . . 8 ⊢ (𝐴 ≈ 𝑥 → (𝐵 ≈ 𝐴 → 𝑥 ≈ 𝐵))
71	70	ad2antlr 763	. . . . . . 7 ⊢ (((𝑥 ∈ ω ∧ 𝐴 ≈ 𝑥) ∧ 𝐵 ⊊ 𝐴) → (𝐵 ≈ 𝐴 → 𝑥 ≈ 𝐵))
72	66, 71	mtod 189	. . . . . 6 ⊢ (((𝑥 ∈ ω ∧ 𝐴 ≈ 𝑥) ∧ 𝐵 ⊊ 𝐴) → ¬ 𝐵 ≈ 𝐴)
73		brsdom 7978	. . . . . 6 ⊢ (𝐵 ≺ 𝐴 ↔ (𝐵 ≼ 𝐴 ∧ ¬ 𝐵 ≈ 𝐴))
74	8, 72, 73	sylanbrc 698	. . . . 5 ⊢ (((𝑥 ∈ ω ∧ 𝐴 ≈ 𝑥) ∧ 𝐵 ⊊ 𝐴) → 𝐵 ≺ 𝐴)
75	74	exp31 630	. . . 4 ⊢ (𝑥 ∈ ω → (𝐴 ≈ 𝑥 → (𝐵 ⊊ 𝐴 → 𝐵 ≺ 𝐴)))
76	75	rexlimiv 3027	. . 3 ⊢ (∃𝑥 ∈ ω 𝐴 ≈ 𝑥 → (𝐵 ⊊ 𝐴 → 𝐵 ≺ 𝐴))
77	1, 76	sylbi 207	. 2 ⊢ (𝐴 ∈ Fin → (𝐵 ⊊ 𝐴 → 𝐵 ≺ 𝐴))
78	77	imp 445	1 ⊢ ((𝐴 ∈ Fin ∧ 𝐵 ⊊ 𝐴) → 𝐵 ≺ 𝐴)

Syntax hints:  ¬ wn 3   → wi 4   ↔ wb 196   ∧ wa 384   = wceq 1483  ∃wex 1704   ∈ wcel 1990  ∃wrex 2913  Vcvv 3200   ∖ cdif 3571   ⊆ wss 3574   ⊊ wpss 3575  ∅c0 3915   class class class wbr 4653  ^◡ccnv 5113  dom cdm 5114  ran crn 5115   ↾ cres 5116   “ cima 5117  Fun wfun 5882   Fn wfn 5883  –1-1→wf1 5885  –onto→wfo 5886  –1-1-onto→wf1o 5887  ‘cfv 5888  ωcom 7065   ≈ cen 7952   ≼ cdom 7953   ≺ csdm 7954  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-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-er 7742  df-en 7956  df-dom 7957  df-sdom 7958  df-fin 7959

This theorem is referenced by:  pssinf  8170  f1finf1o  8187  findcard3  8203  fofinf1o  8241  ackbij1b  9061  fincssdom  9145  fin23lem25  9146  canthp1lem2  9475  pwfseqlem4  9484  uzindi  12781  symggen  17890  pgpssslw  18029  pgpfaclem2  18481  ppiltx  24903  finminlem  32312  lindsenlbs  33404