Metamath Proof Explorer


Theorem iundisj2fi

Description: A disjoint union is disjoint, finite version. Cf. iundisj2 . (Contributed by Thierry Arnoux, 16-Feb-2017)

Ref Expression
Hypotheses iundisj2fi.0 𝑛 𝐵
iundisj2fi.1 ( 𝑛 = 𝑘𝐴 = 𝐵 )
Assertion iundisj2fi Disj 𝑛 ∈ ( 1 ..^ 𝑁 ) ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 )

Proof

Step Hyp Ref Expression
1 iundisj2fi.0 𝑛 𝐵
2 iundisj2fi.1 ( 𝑛 = 𝑘𝐴 = 𝐵 )
3 tru
4 eqeq12 ( ( 𝑎 = 𝑥𝑏 = 𝑦 ) → ( 𝑎 = 𝑏𝑥 = 𝑦 ) )
5 csbeq1 ( 𝑎 = 𝑥 𝑎 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) = 𝑥 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) )
6 csbeq1 ( 𝑏 = 𝑦 𝑏 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) = 𝑦 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) )
7 5 6 ineqan12d ( ( 𝑎 = 𝑥𝑏 = 𝑦 ) → ( 𝑎 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑏 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) = ( 𝑥 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑦 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) )
8 7 eqeq1d ( ( 𝑎 = 𝑥𝑏 = 𝑦 ) → ( ( 𝑎 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑏 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) = ∅ ↔ ( 𝑥 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑦 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) = ∅ ) )
9 4 8 orbi12d ( ( 𝑎 = 𝑥𝑏 = 𝑦 ) → ( ( 𝑎 = 𝑏 ∨ ( 𝑎 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑏 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) = ∅ ) ↔ ( 𝑥 = 𝑦 ∨ ( 𝑥 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑦 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) = ∅ ) ) )
10 eqeq12 ( ( 𝑎 = 𝑦𝑏 = 𝑥 ) → ( 𝑎 = 𝑏𝑦 = 𝑥 ) )
11 equcom ( 𝑦 = 𝑥𝑥 = 𝑦 )
12 10 11 bitrdi ( ( 𝑎 = 𝑦𝑏 = 𝑥 ) → ( 𝑎 = 𝑏𝑥 = 𝑦 ) )
13 csbeq1 ( 𝑎 = 𝑦 𝑎 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) = 𝑦 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) )
14 csbeq1 ( 𝑏 = 𝑥 𝑏 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) = 𝑥 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) )
15 13 14 ineqan12d ( ( 𝑎 = 𝑦𝑏 = 𝑥 ) → ( 𝑎 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑏 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) = ( 𝑦 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑥 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) )
16 incom ( 𝑦 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑥 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) = ( 𝑥 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑦 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) )
17 15 16 eqtrdi ( ( 𝑎 = 𝑦𝑏 = 𝑥 ) → ( 𝑎 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑏 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) = ( 𝑥 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑦 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) )
18 17 eqeq1d ( ( 𝑎 = 𝑦𝑏 = 𝑥 ) → ( ( 𝑎 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑏 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) = ∅ ↔ ( 𝑥 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑦 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) = ∅ ) )
19 12 18 orbi12d ( ( 𝑎 = 𝑦𝑏 = 𝑥 ) → ( ( 𝑎 = 𝑏 ∨ ( 𝑎 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑏 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) = ∅ ) ↔ ( 𝑥 = 𝑦 ∨ ( 𝑥 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑦 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) = ∅ ) ) )
20 fzossnn ( 1 ..^ 𝑁 ) ⊆ ℕ
21 nnssre ℕ ⊆ ℝ
22 20 21 sstri ( 1 ..^ 𝑁 ) ⊆ ℝ
23 22 a1i ( ⊤ → ( 1 ..^ 𝑁 ) ⊆ ℝ )
24 biidd ( ( ⊤ ∧ ( 𝑥 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑦 ∈ ( 1 ..^ 𝑁 ) ) ) → ( ( 𝑥 = 𝑦 ∨ ( 𝑥 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑦 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) = ∅ ) ↔ ( 𝑥 = 𝑦 ∨ ( 𝑥 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑦 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) = ∅ ) ) )
25 nesym ( 𝑦𝑥 ↔ ¬ 𝑥 = 𝑦 )
26 22 sseli ( 𝑥 ∈ ( 1 ..^ 𝑁 ) → 𝑥 ∈ ℝ )
27 22 sseli ( 𝑦 ∈ ( 1 ..^ 𝑁 ) → 𝑦 ∈ ℝ )
28 id ( 𝑥𝑦𝑥𝑦 )
29 leltne ( ( 𝑥 ∈ ℝ ∧ 𝑦 ∈ ℝ ∧ 𝑥𝑦 ) → ( 𝑥 < 𝑦𝑦𝑥 ) )
30 26 27 28 29 syl3an ( ( 𝑥 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑦 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑥𝑦 ) → ( 𝑥 < 𝑦𝑦𝑥 ) )
31 vex 𝑥 ∈ V
32 nfcsb1v 𝑛 𝑥 / 𝑛 𝐴
33 nfcv 𝑛 ( 1 ..^ 𝑥 )
34 33 1 nfiun 𝑛 𝑘 ∈ ( 1 ..^ 𝑥 ) 𝐵
35 32 34 nfdif 𝑛 ( 𝑥 / 𝑛 𝐴 𝑘 ∈ ( 1 ..^ 𝑥 ) 𝐵 )
36 csbeq1a ( 𝑛 = 𝑥𝐴 = 𝑥 / 𝑛 𝐴 )
37 oveq2 ( 𝑛 = 𝑥 → ( 1 ..^ 𝑛 ) = ( 1 ..^ 𝑥 ) )
38 37 iuneq1d ( 𝑛 = 𝑥 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 = 𝑘 ∈ ( 1 ..^ 𝑥 ) 𝐵 )
39 36 38 difeq12d ( 𝑛 = 𝑥 → ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) = ( 𝑥 / 𝑛 𝐴 𝑘 ∈ ( 1 ..^ 𝑥 ) 𝐵 ) )
40 31 35 39 csbief 𝑥 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) = ( 𝑥 / 𝑛 𝐴 𝑘 ∈ ( 1 ..^ 𝑥 ) 𝐵 )
41 vex 𝑦 ∈ V
42 nfcsb1v 𝑛 𝑦 / 𝑛 𝐴
43 nfcv 𝑛 ( 1 ..^ 𝑦 )
44 43 1 nfiun 𝑛 𝑘 ∈ ( 1 ..^ 𝑦 ) 𝐵
45 42 44 nfdif 𝑛 ( 𝑦 / 𝑛 𝐴 𝑘 ∈ ( 1 ..^ 𝑦 ) 𝐵 )
46 csbeq1a ( 𝑛 = 𝑦𝐴 = 𝑦 / 𝑛 𝐴 )
47 oveq2 ( 𝑛 = 𝑦 → ( 1 ..^ 𝑛 ) = ( 1 ..^ 𝑦 ) )
48 47 iuneq1d ( 𝑛 = 𝑦 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 = 𝑘 ∈ ( 1 ..^ 𝑦 ) 𝐵 )
49 46 48 difeq12d ( 𝑛 = 𝑦 → ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) = ( 𝑦 / 𝑛 𝐴 𝑘 ∈ ( 1 ..^ 𝑦 ) 𝐵 ) )
50 41 45 49 csbief 𝑦 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) = ( 𝑦 / 𝑛 𝐴 𝑘 ∈ ( 1 ..^ 𝑦 ) 𝐵 )
51 40 50 ineq12i ( 𝑥 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑦 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) = ( ( 𝑥 / 𝑛 𝐴 𝑘 ∈ ( 1 ..^ 𝑥 ) 𝐵 ) ∩ ( 𝑦 / 𝑛 𝐴 𝑘 ∈ ( 1 ..^ 𝑦 ) 𝐵 ) )
52 simp1 ( ( 𝑥 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑦 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑥 < 𝑦 ) → 𝑥 ∈ ( 1 ..^ 𝑁 ) )
53 20 52 sselid ( ( 𝑥 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑦 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑥 < 𝑦 ) → 𝑥 ∈ ℕ )
54 nnuz ℕ = ( ℤ ‘ 1 )
55 53 54 eleqtrdi ( ( 𝑥 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑦 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑥 < 𝑦 ) → 𝑥 ∈ ( ℤ ‘ 1 ) )
56 simp2 ( ( 𝑥 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑦 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑥 < 𝑦 ) → 𝑦 ∈ ( 1 ..^ 𝑁 ) )
57 20 56 sselid ( ( 𝑥 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑦 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑥 < 𝑦 ) → 𝑦 ∈ ℕ )
58 57 nnzd ( ( 𝑥 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑦 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑥 < 𝑦 ) → 𝑦 ∈ ℤ )
59 simp3 ( ( 𝑥 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑦 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑥 < 𝑦 ) → 𝑥 < 𝑦 )
60 elfzo2 ( 𝑥 ∈ ( 1 ..^ 𝑦 ) ↔ ( 𝑥 ∈ ( ℤ ‘ 1 ) ∧ 𝑦 ∈ ℤ ∧ 𝑥 < 𝑦 ) )
61 55 58 59 60 syl3anbrc ( ( 𝑥 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑦 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑥 < 𝑦 ) → 𝑥 ∈ ( 1 ..^ 𝑦 ) )
62 nfcv 𝑛 𝑘
63 62 1 2 csbhypf ( 𝑥 = 𝑘 𝑥 / 𝑛 𝐴 = 𝐵 )
64 63 equcoms ( 𝑘 = 𝑥 𝑥 / 𝑛 𝐴 = 𝐵 )
65 64 eqcomd ( 𝑘 = 𝑥𝐵 = 𝑥 / 𝑛 𝐴 )
66 65 ssiun2s ( 𝑥 ∈ ( 1 ..^ 𝑦 ) → 𝑥 / 𝑛 𝐴 𝑘 ∈ ( 1 ..^ 𝑦 ) 𝐵 )
67 61 66 syl ( ( 𝑥 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑦 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑥 < 𝑦 ) → 𝑥 / 𝑛 𝐴 𝑘 ∈ ( 1 ..^ 𝑦 ) 𝐵 )
68 67 ssdifssd ( ( 𝑥 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑦 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑥 < 𝑦 ) → ( 𝑥 / 𝑛 𝐴 𝑘 ∈ ( 1 ..^ 𝑥 ) 𝐵 ) ⊆ 𝑘 ∈ ( 1 ..^ 𝑦 ) 𝐵 )
69 68 ssrind ( ( 𝑥 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑦 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑥 < 𝑦 ) → ( ( 𝑥 / 𝑛 𝐴 𝑘 ∈ ( 1 ..^ 𝑥 ) 𝐵 ) ∩ ( 𝑦 / 𝑛 𝐴 𝑘 ∈ ( 1 ..^ 𝑦 ) 𝐵 ) ) ⊆ ( 𝑘 ∈ ( 1 ..^ 𝑦 ) 𝐵 ∩ ( 𝑦 / 𝑛 𝐴 𝑘 ∈ ( 1 ..^ 𝑦 ) 𝐵 ) ) )
70 51 69 eqsstrid ( ( 𝑥 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑦 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑥 < 𝑦 ) → ( 𝑥 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑦 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) ⊆ ( 𝑘 ∈ ( 1 ..^ 𝑦 ) 𝐵 ∩ ( 𝑦 / 𝑛 𝐴 𝑘 ∈ ( 1 ..^ 𝑦 ) 𝐵 ) ) )
71 disjdif ( 𝑘 ∈ ( 1 ..^ 𝑦 ) 𝐵 ∩ ( 𝑦 / 𝑛 𝐴 𝑘 ∈ ( 1 ..^ 𝑦 ) 𝐵 ) ) = ∅
72 sseq0 ( ( ( 𝑥 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑦 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) ⊆ ( 𝑘 ∈ ( 1 ..^ 𝑦 ) 𝐵 ∩ ( 𝑦 / 𝑛 𝐴 𝑘 ∈ ( 1 ..^ 𝑦 ) 𝐵 ) ) ∧ ( 𝑘 ∈ ( 1 ..^ 𝑦 ) 𝐵 ∩ ( 𝑦 / 𝑛 𝐴 𝑘 ∈ ( 1 ..^ 𝑦 ) 𝐵 ) ) = ∅ ) → ( 𝑥 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑦 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) = ∅ )
73 70 71 72 sylancl ( ( 𝑥 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑦 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑥 < 𝑦 ) → ( 𝑥 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑦 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) = ∅ )
74 73 3expia ( ( 𝑥 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑦 ∈ ( 1 ..^ 𝑁 ) ) → ( 𝑥 < 𝑦 → ( 𝑥 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑦 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) = ∅ ) )
75 74 3adant3 ( ( 𝑥 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑦 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑥𝑦 ) → ( 𝑥 < 𝑦 → ( 𝑥 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑦 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) = ∅ ) )
76 30 75 sylbird ( ( 𝑥 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑦 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑥𝑦 ) → ( 𝑦𝑥 → ( 𝑥 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑦 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) = ∅ ) )
77 25 76 syl5bir ( ( 𝑥 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑦 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑥𝑦 ) → ( ¬ 𝑥 = 𝑦 → ( 𝑥 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑦 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) = ∅ ) )
78 77 orrd ( ( 𝑥 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑦 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑥𝑦 ) → ( 𝑥 = 𝑦 ∨ ( 𝑥 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑦 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) = ∅ ) )
79 78 adantl ( ( ⊤ ∧ ( 𝑥 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑦 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑥𝑦 ) ) → ( 𝑥 = 𝑦 ∨ ( 𝑥 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑦 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) = ∅ ) )
80 9 19 23 24 79 wlogle ( ( ⊤ ∧ ( 𝑥 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑦 ∈ ( 1 ..^ 𝑁 ) ) ) → ( 𝑥 = 𝑦 ∨ ( 𝑥 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑦 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) = ∅ ) )
81 3 80 mpan ( ( 𝑥 ∈ ( 1 ..^ 𝑁 ) ∧ 𝑦 ∈ ( 1 ..^ 𝑁 ) ) → ( 𝑥 = 𝑦 ∨ ( 𝑥 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑦 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) = ∅ ) )
82 81 rgen2 𝑥 ∈ ( 1 ..^ 𝑁 ) ∀ 𝑦 ∈ ( 1 ..^ 𝑁 ) ( 𝑥 = 𝑦 ∨ ( 𝑥 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑦 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) = ∅ )
83 disjors ( Disj 𝑛 ∈ ( 1 ..^ 𝑁 ) ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ↔ ∀ 𝑥 ∈ ( 1 ..^ 𝑁 ) ∀ 𝑦 ∈ ( 1 ..^ 𝑁 ) ( 𝑥 = 𝑦 ∨ ( 𝑥 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ∩ 𝑦 / 𝑛 ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 ) ) = ∅ ) )
84 82 83 mpbir Disj 𝑛 ∈ ( 1 ..^ 𝑁 ) ( 𝐴 𝑘 ∈ ( 1 ..^ 𝑛 ) 𝐵 )