Theorem infdif 9031

Description: The cardinality of an infinite set does not change after subtracting a strictly smaller one. Example in [Enderton] p. 164. (Contributed by NM, 22-Oct-2004.) (Revised by Mario Carneiro, 29-Apr-2015.)

Assertion

Ref	Expression
infdif	⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → (𝐴 ∖ 𝐵) ≈ 𝐴)

Proof of Theorem infdif

Step	Hyp	Ref	Expression
1		simp1 1061	. . 3 ⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → 𝐴 ∈ dom card)
2		difss 3737	. . 3 ⊢ (𝐴 ∖ 𝐵) ⊆ 𝐴
3		ssdomg 8001	. . 3 ⊢ (𝐴 ∈ dom card → ((𝐴 ∖ 𝐵) ⊆ 𝐴 → (𝐴 ∖ 𝐵) ≼ 𝐴))
4	1, 2, 3	mpisyl 21	. 2 ⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → (𝐴 ∖ 𝐵) ≼ 𝐴)
5		sdomdom 7983	. . . . . . . . 9 ⊢ (𝐵 ≺ 𝐴 → 𝐵 ≼ 𝐴)
6	5	3ad2ant3 1084	. . . . . . . 8 ⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → 𝐵 ≼ 𝐴)
7		numdom 8861	. . . . . . . 8 ⊢ ((𝐴 ∈ dom card ∧ 𝐵 ≼ 𝐴) → 𝐵 ∈ dom card)
8	1, 6, 7	syl2anc 693	. . . . . . 7 ⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → 𝐵 ∈ dom card)
9		unnum 9022	. . . . . . 7 ⊢ ((𝐴 ∈ dom card ∧ 𝐵 ∈ dom card) → (𝐴 ∪ 𝐵) ∈ dom card)
10	1, 8, 9	syl2anc 693	. . . . . 6 ⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → (𝐴 ∪ 𝐵) ∈ dom card)
11		ssun1 3776	. . . . . 6 ⊢ 𝐴 ⊆ (𝐴 ∪ 𝐵)
12		ssdomg 8001	. . . . . 6 ⊢ ((𝐴 ∪ 𝐵) ∈ dom card → (𝐴 ⊆ (𝐴 ∪ 𝐵) → 𝐴 ≼ (𝐴 ∪ 𝐵)))
13	10, 11, 12	mpisyl 21	. . . . 5 ⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → 𝐴 ≼ (𝐴 ∪ 𝐵))
14		undif1 4043	. . . . . 6 ⊢ ((𝐴 ∖ 𝐵) ∪ 𝐵) = (𝐴 ∪ 𝐵)
15		ssnum 8862	. . . . . . . 8 ⊢ ((𝐴 ∈ dom card ∧ (𝐴 ∖ 𝐵) ⊆ 𝐴) → (𝐴 ∖ 𝐵) ∈ dom card)
16	1, 2, 15	sylancl 694	. . . . . . 7 ⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → (𝐴 ∖ 𝐵) ∈ dom card)
17		uncdadom 8993	. . . . . . 7 ⊢ (((𝐴 ∖ 𝐵) ∈ dom card ∧ 𝐵 ∈ dom card) → ((𝐴 ∖ 𝐵) ∪ 𝐵) ≼ ((𝐴 ∖ 𝐵) +𝑐 𝐵))
18	16, 8, 17	syl2anc 693	. . . . . 6 ⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → ((𝐴 ∖ 𝐵) ∪ 𝐵) ≼ ((𝐴 ∖ 𝐵) +𝑐 𝐵))
19	14, 18	syl5eqbrr 4689	. . . . 5 ⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → (𝐴 ∪ 𝐵) ≼ ((𝐴 ∖ 𝐵) +𝑐 𝐵))
20		domtr 8009	. . . . 5 ⊢ ((𝐴 ≼ (𝐴 ∪ 𝐵) ∧ (𝐴 ∪ 𝐵) ≼ ((𝐴 ∖ 𝐵) +𝑐 𝐵)) → 𝐴 ≼ ((𝐴 ∖ 𝐵) +𝑐 𝐵))
21	13, 19, 20	syl2anc 693	. . . 4 ⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → 𝐴 ≼ ((𝐴 ∖ 𝐵) +𝑐 𝐵))
22		simp3 1063	. . . . . . 7 ⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → 𝐵 ≺ 𝐴)
23		sdomdom 7983	. . . . . . . . 9 ⊢ ((𝐴 ∖ 𝐵) ≺ 𝐵 → (𝐴 ∖ 𝐵) ≼ 𝐵)
24		cdadom1 9008	. . . . . . . . 9 ⊢ ((𝐴 ∖ 𝐵) ≼ 𝐵 → ((𝐴 ∖ 𝐵) +𝑐 𝐵) ≼ (𝐵 +𝑐 𝐵))
25	23, 24	syl 17	. . . . . . . 8 ⊢ ((𝐴 ∖ 𝐵) ≺ 𝐵 → ((𝐴 ∖ 𝐵) +𝑐 𝐵) ≼ (𝐵 +𝑐 𝐵))
26		domtr 8009	. . . . . . . . . . 11 ⊢ ((𝐴 ≼ ((𝐴 ∖ 𝐵) +𝑐 𝐵) ∧ ((𝐴 ∖ 𝐵) +𝑐 𝐵) ≼ (𝐵 +𝑐 𝐵)) → 𝐴 ≼ (𝐵 +𝑐 𝐵))
27	26	ex 450	. . . . . . . . . 10 ⊢ (𝐴 ≼ ((𝐴 ∖ 𝐵) +𝑐 𝐵) → (((𝐴 ∖ 𝐵) +𝑐 𝐵) ≼ (𝐵 +𝑐 𝐵) → 𝐴 ≼ (𝐵 +𝑐 𝐵)))
28	21, 27	syl 17	. . . . . . . . 9 ⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → (((𝐴 ∖ 𝐵) +𝑐 𝐵) ≼ (𝐵 +𝑐 𝐵) → 𝐴 ≼ (𝐵 +𝑐 𝐵)))
29		simp2 1062	. . . . . . . . . . . 12 ⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → ω ≼ 𝐴)
30		domtr 8009	. . . . . . . . . . . . 13 ⊢ ((ω ≼ 𝐴 ∧ 𝐴 ≼ (𝐵 +𝑐 𝐵)) → ω ≼ (𝐵 +𝑐 𝐵))
31	30	ex 450	. . . . . . . . . . . 12 ⊢ (ω ≼ 𝐴 → (𝐴 ≼ (𝐵 +𝑐 𝐵) → ω ≼ (𝐵 +𝑐 𝐵)))
32	29, 31	syl 17	. . . . . . . . . . 11 ⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → (𝐴 ≼ (𝐵 +𝑐 𝐵) → ω ≼ (𝐵 +𝑐 𝐵)))
33		cdainf 9014	. . . . . . . . . . . . 13 ⊢ (ω ≼ 𝐵 ↔ ω ≼ (𝐵 +𝑐 𝐵))
34	33	biimpri 218	. . . . . . . . . . . 12 ⊢ (ω ≼ (𝐵 +𝑐 𝐵) → ω ≼ 𝐵)
35		domrefg 7990	. . . . . . . . . . . . 13 ⊢ (𝐵 ∈ dom card → 𝐵 ≼ 𝐵)
36		infcdaabs 9028	. . . . . . . . . . . . . . 15 ⊢ ((𝐵 ∈ dom card ∧ ω ≼ 𝐵 ∧ 𝐵 ≼ 𝐵) → (𝐵 +𝑐 𝐵) ≈ 𝐵)
37	36	3com23 1271	. . . . . . . . . . . . . 14 ⊢ ((𝐵 ∈ dom card ∧ 𝐵 ≼ 𝐵 ∧ ω ≼ 𝐵) → (𝐵 +𝑐 𝐵) ≈ 𝐵)
38	37	3expia 1267	. . . . . . . . . . . . 13 ⊢ ((𝐵 ∈ dom card ∧ 𝐵 ≼ 𝐵) → (ω ≼ 𝐵 → (𝐵 +𝑐 𝐵) ≈ 𝐵))
39	35, 38	mpdan 702	. . . . . . . . . . . 12 ⊢ (𝐵 ∈ dom card → (ω ≼ 𝐵 → (𝐵 +𝑐 𝐵) ≈ 𝐵))
40	8, 34, 39	syl2im 40	. . . . . . . . . . 11 ⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → (ω ≼ (𝐵 +𝑐 𝐵) → (𝐵 +𝑐 𝐵) ≈ 𝐵))
41	32, 40	syld 47	. . . . . . . . . 10 ⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → (𝐴 ≼ (𝐵 +𝑐 𝐵) → (𝐵 +𝑐 𝐵) ≈ 𝐵))
42		domen2 8103	. . . . . . . . . . 11 ⊢ ((𝐵 +𝑐 𝐵) ≈ 𝐵 → (𝐴 ≼ (𝐵 +𝑐 𝐵) ↔ 𝐴 ≼ 𝐵))
43	42	biimpcd 239	. . . . . . . . . 10 ⊢ (𝐴 ≼ (𝐵 +𝑐 𝐵) → ((𝐵 +𝑐 𝐵) ≈ 𝐵 → 𝐴 ≼ 𝐵))
44	41, 43	sylcom 30	. . . . . . . . 9 ⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → (𝐴 ≼ (𝐵 +𝑐 𝐵) → 𝐴 ≼ 𝐵))
45	28, 44	syld 47	. . . . . . . 8 ⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → (((𝐴 ∖ 𝐵) +𝑐 𝐵) ≼ (𝐵 +𝑐 𝐵) → 𝐴 ≼ 𝐵))
46		domnsym 8086	. . . . . . . 8 ⊢ (𝐴 ≼ 𝐵 → ¬ 𝐵 ≺ 𝐴)
47	25, 45, 46	syl56 36	. . . . . . 7 ⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → ((𝐴 ∖ 𝐵) ≺ 𝐵 → ¬ 𝐵 ≺ 𝐴))
48	22, 47	mt2d 131	. . . . . 6 ⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → ¬ (𝐴 ∖ 𝐵) ≺ 𝐵)
49		domtri2 8815	. . . . . . 7 ⊢ ((𝐵 ∈ dom card ∧ (𝐴 ∖ 𝐵) ∈ dom card) → (𝐵 ≼ (𝐴 ∖ 𝐵) ↔ ¬ (𝐴 ∖ 𝐵) ≺ 𝐵))
50	8, 16, 49	syl2anc 693	. . . . . 6 ⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → (𝐵 ≼ (𝐴 ∖ 𝐵) ↔ ¬ (𝐴 ∖ 𝐵) ≺ 𝐵))
51	48, 50	mpbird 247	. . . . 5 ⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → 𝐵 ≼ (𝐴 ∖ 𝐵))
52		cdadom2 9009	. . . . 5 ⊢ (𝐵 ≼ (𝐴 ∖ 𝐵) → ((𝐴 ∖ 𝐵) +𝑐 𝐵) ≼ ((𝐴 ∖ 𝐵) +𝑐 (𝐴 ∖ 𝐵)))
53	51, 52	syl 17	. . . 4 ⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → ((𝐴 ∖ 𝐵) +𝑐 𝐵) ≼ ((𝐴 ∖ 𝐵) +𝑐 (𝐴 ∖ 𝐵)))
54		domtr 8009	. . . 4 ⊢ ((𝐴 ≼ ((𝐴 ∖ 𝐵) +𝑐 𝐵) ∧ ((𝐴 ∖ 𝐵) +𝑐 𝐵) ≼ ((𝐴 ∖ 𝐵) +𝑐 (𝐴 ∖ 𝐵))) → 𝐴 ≼ ((𝐴 ∖ 𝐵) +𝑐 (𝐴 ∖ 𝐵)))
55	21, 53, 54	syl2anc 693	. . 3 ⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → 𝐴 ≼ ((𝐴 ∖ 𝐵) +𝑐 (𝐴 ∖ 𝐵)))
56		domtr 8009	. . . . . 6 ⊢ ((ω ≼ 𝐴 ∧ 𝐴 ≼ ((𝐴 ∖ 𝐵) +𝑐 (𝐴 ∖ 𝐵))) → ω ≼ ((𝐴 ∖ 𝐵) +𝑐 (𝐴 ∖ 𝐵)))
57	29, 55, 56	syl2anc 693	. . . . 5 ⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → ω ≼ ((𝐴 ∖ 𝐵) +𝑐 (𝐴 ∖ 𝐵)))
58		cdainf 9014	. . . . 5 ⊢ (ω ≼ (𝐴 ∖ 𝐵) ↔ ω ≼ ((𝐴 ∖ 𝐵) +𝑐 (𝐴 ∖ 𝐵)))
59	57, 58	sylibr 224	. . . 4 ⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → ω ≼ (𝐴 ∖ 𝐵))
60		domrefg 7990	. . . . 5 ⊢ ((𝐴 ∖ 𝐵) ∈ dom card → (𝐴 ∖ 𝐵) ≼ (𝐴 ∖ 𝐵))
61	16, 60	syl 17	. . . 4 ⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → (𝐴 ∖ 𝐵) ≼ (𝐴 ∖ 𝐵))
62		infcdaabs 9028	. . . 4 ⊢ (((𝐴 ∖ 𝐵) ∈ dom card ∧ ω ≼ (𝐴 ∖ 𝐵) ∧ (𝐴 ∖ 𝐵) ≼ (𝐴 ∖ 𝐵)) → ((𝐴 ∖ 𝐵) +𝑐 (𝐴 ∖ 𝐵)) ≈ (𝐴 ∖ 𝐵))
63	16, 59, 61, 62	syl3anc 1326	. . 3 ⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → ((𝐴 ∖ 𝐵) +𝑐 (𝐴 ∖ 𝐵)) ≈ (𝐴 ∖ 𝐵))
64		domentr 8015	. . 3 ⊢ ((𝐴 ≼ ((𝐴 ∖ 𝐵) +𝑐 (𝐴 ∖ 𝐵)) ∧ ((𝐴 ∖ 𝐵) +𝑐 (𝐴 ∖ 𝐵)) ≈ (𝐴 ∖ 𝐵)) → 𝐴 ≼ (𝐴 ∖ 𝐵))
65	55, 63, 64	syl2anc 693	. 2 ⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → 𝐴 ≼ (𝐴 ∖ 𝐵))
66		sbth 8080	. 2 ⊢ (((𝐴 ∖ 𝐵) ≼ 𝐴 ∧ 𝐴 ≼ (𝐴 ∖ 𝐵)) → (𝐴 ∖ 𝐵) ≈ 𝐴)
67	4, 65, 66	syl2anc 693	1 ⊢ ((𝐴 ∈ dom card ∧ ω ≼ 𝐴 ∧ 𝐵 ≺ 𝐴) → (𝐴 ∖ 𝐵) ≈ 𝐴)

Syntax hints:  ¬ wn 3   → wi 4   ↔ wb 196   ∧ w3a 1037   ∈ wcel 1990   ∖ cdif 3571   ∪ cun 3572   ⊆ wss 3574   class class class wbr 4653  dom cdm 5114  (class class class)co 6650  ωcom 7065   ≈ cen 7952   ≼ cdom 7953   ≺ csdm 7954  cardccrd 8761   +_𝑐 ccda 8989

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-rep 4771  ax-sep 4781  ax-nul 4789  ax-pow 4843  ax-pr 4906  ax-un 6949  ax-inf2 8538

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-rmo 2920  df-rab 2921  df-v 3202  df-sbc 3436  df-csb 3534  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-int 4476  df-iun 4522  df-br 4654  df-opab 4713  df-mpt 4730  df-tr 4753  df-id 5024  df-eprel 5029  df-po 5035  df-so 5036  df-fr 5073  df-se 5074  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-pred 5680  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-isom 5897  df-riota 6611  df-ov 6653  df-oprab 6654  df-mpt2 6655  df-om 7066  df-1st 7168  df-2nd 7169  df-wrecs 7407  df-recs 7468  df-rdg 7506  df-1o 7560  df-2o 7561  df-oadd 7564  df-er 7742  df-en 7956  df-dom 7957  df-sdom 7958  df-fin 7959  df-oi 8415  df-card 8765  df-cda 8990

This theorem is referenced by:  infdif2  9032  alephsuc3  9402  aleph1irr  14975