Metamath Proof Explorer


Theorem naddsuc2

Description: Natural addition with successor. (Contributed by RP, 1-Jan-2025)

Ref Expression
Assertion naddsuc2 ( ( 𝐴 ∈ On ∧ 𝐵 ∈ On ) → ( 𝐴 +no suc 𝐵 ) = suc ( 𝐴 +no 𝐵 ) )

Proof

Step Hyp Ref Expression
1 oveq1 ( 𝑎 = 𝑐 → ( 𝑎 +no suc 𝑏 ) = ( 𝑐 +no suc 𝑏 ) )
2 oveq1 ( 𝑎 = 𝑐 → ( 𝑎 +no 𝑏 ) = ( 𝑐 +no 𝑏 ) )
3 suceq ( ( 𝑎 +no 𝑏 ) = ( 𝑐 +no 𝑏 ) → suc ( 𝑎 +no 𝑏 ) = suc ( 𝑐 +no 𝑏 ) )
4 2 3 syl ( 𝑎 = 𝑐 → suc ( 𝑎 +no 𝑏 ) = suc ( 𝑐 +no 𝑏 ) )
5 1 4 eqeq12d ( 𝑎 = 𝑐 → ( ( 𝑎 +no suc 𝑏 ) = suc ( 𝑎 +no 𝑏 ) ↔ ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) ) )
6 suceq ( 𝑏 = 𝑑 → suc 𝑏 = suc 𝑑 )
7 6 oveq2d ( 𝑏 = 𝑑 → ( 𝑐 +no suc 𝑏 ) = ( 𝑐 +no suc 𝑑 ) )
8 oveq2 ( 𝑏 = 𝑑 → ( 𝑐 +no 𝑏 ) = ( 𝑐 +no 𝑑 ) )
9 suceq ( ( 𝑐 +no 𝑏 ) = ( 𝑐 +no 𝑑 ) → suc ( 𝑐 +no 𝑏 ) = suc ( 𝑐 +no 𝑑 ) )
10 8 9 syl ( 𝑏 = 𝑑 → suc ( 𝑐 +no 𝑏 ) = suc ( 𝑐 +no 𝑑 ) )
11 7 10 eqeq12d ( 𝑏 = 𝑑 → ( ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) ↔ ( 𝑐 +no suc 𝑑 ) = suc ( 𝑐 +no 𝑑 ) ) )
12 oveq1 ( 𝑎 = 𝑐 → ( 𝑎 +no suc 𝑑 ) = ( 𝑐 +no suc 𝑑 ) )
13 oveq1 ( 𝑎 = 𝑐 → ( 𝑎 +no 𝑑 ) = ( 𝑐 +no 𝑑 ) )
14 suceq ( ( 𝑎 +no 𝑑 ) = ( 𝑐 +no 𝑑 ) → suc ( 𝑎 +no 𝑑 ) = suc ( 𝑐 +no 𝑑 ) )
15 13 14 syl ( 𝑎 = 𝑐 → suc ( 𝑎 +no 𝑑 ) = suc ( 𝑐 +no 𝑑 ) )
16 12 15 eqeq12d ( 𝑎 = 𝑐 → ( ( 𝑎 +no suc 𝑑 ) = suc ( 𝑎 +no 𝑑 ) ↔ ( 𝑐 +no suc 𝑑 ) = suc ( 𝑐 +no 𝑑 ) ) )
17 oveq1 ( 𝑎 = 𝐴 → ( 𝑎 +no suc 𝑏 ) = ( 𝐴 +no suc 𝑏 ) )
18 oveq1 ( 𝑎 = 𝐴 → ( 𝑎 +no 𝑏 ) = ( 𝐴 +no 𝑏 ) )
19 suceq ( ( 𝑎 +no 𝑏 ) = ( 𝐴 +no 𝑏 ) → suc ( 𝑎 +no 𝑏 ) = suc ( 𝐴 +no 𝑏 ) )
20 18 19 syl ( 𝑎 = 𝐴 → suc ( 𝑎 +no 𝑏 ) = suc ( 𝐴 +no 𝑏 ) )
21 17 20 eqeq12d ( 𝑎 = 𝐴 → ( ( 𝑎 +no suc 𝑏 ) = suc ( 𝑎 +no 𝑏 ) ↔ ( 𝐴 +no suc 𝑏 ) = suc ( 𝐴 +no 𝑏 ) ) )
22 suceq ( 𝑏 = 𝐵 → suc 𝑏 = suc 𝐵 )
23 22 oveq2d ( 𝑏 = 𝐵 → ( 𝐴 +no suc 𝑏 ) = ( 𝐴 +no suc 𝐵 ) )
24 oveq2 ( 𝑏 = 𝐵 → ( 𝐴 +no 𝑏 ) = ( 𝐴 +no 𝐵 ) )
25 suceq ( ( 𝐴 +no 𝑏 ) = ( 𝐴 +no 𝐵 ) → suc ( 𝐴 +no 𝑏 ) = suc ( 𝐴 +no 𝐵 ) )
26 24 25 syl ( 𝑏 = 𝐵 → suc ( 𝐴 +no 𝑏 ) = suc ( 𝐴 +no 𝐵 ) )
27 23 26 eqeq12d ( 𝑏 = 𝐵 → ( ( 𝐴 +no suc 𝑏 ) = suc ( 𝐴 +no 𝑏 ) ↔ ( 𝐴 +no suc 𝐵 ) = suc ( 𝐴 +no 𝐵 ) ) )
28 simp2 ( ( ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 +no suc 𝑑 ) = suc ( 𝑐 +no 𝑑 ) ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) ∧ ∀ 𝑑𝑏 ( 𝑎 +no suc 𝑑 ) = suc ( 𝑎 +no 𝑑 ) ) → ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) )
29 28 a1i ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) → ( ( ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 +no suc 𝑑 ) = suc ( 𝑐 +no 𝑑 ) ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) ∧ ∀ 𝑑𝑏 ( 𝑎 +no suc 𝑑 ) = suc ( 𝑎 +no 𝑑 ) ) → ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) ) )
30 df-suc suc 𝑏 = ( 𝑏 ∪ { 𝑏 } )
31 30 a1i ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) ) ∧ 𝑥 ∈ On ) → suc 𝑏 = ( 𝑏 ∪ { 𝑏 } ) )
32 31 raleqdv ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) ) ∧ 𝑥 ∈ On ) → ( ∀ 𝑑 ∈ suc 𝑏 ( 𝑎 +no 𝑑 ) ∈ 𝑥 ↔ ∀ 𝑑 ∈ ( 𝑏 ∪ { 𝑏 } ) ( 𝑎 +no 𝑑 ) ∈ 𝑥 ) )
33 vex 𝑏 ∈ V
34 33 a1i ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) ) ∧ 𝑥 ∈ On ) → 𝑏 ∈ V )
35 oveq2 ( 𝑑 = 𝑏 → ( 𝑎 +no 𝑑 ) = ( 𝑎 +no 𝑏 ) )
36 35 eleq1d ( 𝑑 = 𝑏 → ( ( 𝑎 +no 𝑑 ) ∈ 𝑥 ↔ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) )
37 36 ralunsn ( 𝑏 ∈ V → ( ∀ 𝑑 ∈ ( 𝑏 ∪ { 𝑏 } ) ( 𝑎 +no 𝑑 ) ∈ 𝑥 ↔ ( ∀ 𝑑𝑏 ( 𝑎 +no 𝑑 ) ∈ 𝑥 ∧ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) ) )
38 34 37 syl ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) ) ∧ 𝑥 ∈ On ) → ( ∀ 𝑑 ∈ ( 𝑏 ∪ { 𝑏 } ) ( 𝑎 +no 𝑑 ) ∈ 𝑥 ↔ ( ∀ 𝑑𝑏 ( 𝑎 +no 𝑑 ) ∈ 𝑥 ∧ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) ) )
39 38 biancomd ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) ) ∧ 𝑥 ∈ On ) → ( ∀ 𝑑 ∈ ( 𝑏 ∪ { 𝑏 } ) ( 𝑎 +no 𝑑 ) ∈ 𝑥 ↔ ( ( 𝑎 +no 𝑏 ) ∈ 𝑥 ∧ ∀ 𝑑𝑏 ( 𝑎 +no 𝑑 ) ∈ 𝑥 ) ) )
40 32 39 bitrd ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) ) ∧ 𝑥 ∈ On ) → ( ∀ 𝑑 ∈ suc 𝑏 ( 𝑎 +no 𝑑 ) ∈ 𝑥 ↔ ( ( 𝑎 +no 𝑏 ) ∈ 𝑥 ∧ ∀ 𝑑𝑏 ( 𝑎 +no 𝑑 ) ∈ 𝑥 ) ) )
41 nfv 𝑐 ( 𝑎 ∈ On ∧ 𝑏 ∈ On )
42 nfra1 𝑐𝑐𝑎 ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 )
43 41 42 nfan 𝑐 ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) )
44 nfv 𝑐 𝑥 ∈ On
45 43 44 nfan 𝑐 ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) ) ∧ 𝑥 ∈ On )
46 simplr ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) ) ∧ 𝑥 ∈ On ) → ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) )
47 46 r19.21bi ( ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) ) ∧ 𝑥 ∈ On ) ∧ 𝑐𝑎 ) → ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) )
48 47 eleq1d ( ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) ) ∧ 𝑥 ∈ On ) ∧ 𝑐𝑎 ) → ( ( 𝑐 +no suc 𝑏 ) ∈ 𝑥 ↔ suc ( 𝑐 +no 𝑏 ) ∈ 𝑥 ) )
49 45 48 ralbida ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) ) ∧ 𝑥 ∈ On ) → ( ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) ∈ 𝑥 ↔ ∀ 𝑐𝑎 suc ( 𝑐 +no 𝑏 ) ∈ 𝑥 ) )
50 40 49 anbi12d ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) ) ∧ 𝑥 ∈ On ) → ( ( ∀ 𝑑 ∈ suc 𝑏 ( 𝑎 +no 𝑑 ) ∈ 𝑥 ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) ∈ 𝑥 ) ↔ ( ( ( 𝑎 +no 𝑏 ) ∈ 𝑥 ∧ ∀ 𝑑𝑏 ( 𝑎 +no 𝑑 ) ∈ 𝑥 ) ∧ ∀ 𝑐𝑎 suc ( 𝑐 +no 𝑏 ) ∈ 𝑥 ) ) )
51 anass ( ( ( ( 𝑎 +no 𝑏 ) ∈ 𝑥 ∧ ∀ 𝑑𝑏 ( 𝑎 +no 𝑑 ) ∈ 𝑥 ) ∧ ∀ 𝑐𝑎 suc ( 𝑐 +no 𝑏 ) ∈ 𝑥 ) ↔ ( ( 𝑎 +no 𝑏 ) ∈ 𝑥 ∧ ( ∀ 𝑑𝑏 ( 𝑎 +no 𝑑 ) ∈ 𝑥 ∧ ∀ 𝑐𝑎 suc ( 𝑐 +no 𝑏 ) ∈ 𝑥 ) ) )
52 simpll3 ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ∧ 𝑥 ∈ On ) ∧ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) ∧ 𝑑𝑏 ) → 𝑥 ∈ On )
53 simpr ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ∧ 𝑥 ∈ On ) ∧ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) ∧ 𝑑𝑏 ) → 𝑑𝑏 )
54 simpll2 ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ∧ 𝑥 ∈ On ) ∧ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) ∧ 𝑑𝑏 ) → 𝑏 ∈ On )
55 onelon ( ( 𝑏 ∈ On ∧ 𝑑𝑏 ) → 𝑑 ∈ On )
56 54 53 55 syl2anc ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ∧ 𝑥 ∈ On ) ∧ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) ∧ 𝑑𝑏 ) → 𝑑 ∈ On )
57 simpll1 ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ∧ 𝑥 ∈ On ) ∧ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) ∧ 𝑑𝑏 ) → 𝑎 ∈ On )
58 naddel2 ( ( 𝑑 ∈ On ∧ 𝑏 ∈ On ∧ 𝑎 ∈ On ) → ( 𝑑𝑏 ↔ ( 𝑎 +no 𝑑 ) ∈ ( 𝑎 +no 𝑏 ) ) )
59 56 54 57 58 syl3anc ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ∧ 𝑥 ∈ On ) ∧ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) ∧ 𝑑𝑏 ) → ( 𝑑𝑏 ↔ ( 𝑎 +no 𝑑 ) ∈ ( 𝑎 +no 𝑏 ) ) )
60 53 59 mpbid ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ∧ 𝑥 ∈ On ) ∧ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) ∧ 𝑑𝑏 ) → ( 𝑎 +no 𝑑 ) ∈ ( 𝑎 +no 𝑏 ) )
61 simplr ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ∧ 𝑥 ∈ On ) ∧ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) ∧ 𝑑𝑏 ) → ( 𝑎 +no 𝑏 ) ∈ 𝑥 )
62 60 61 jca ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ∧ 𝑥 ∈ On ) ∧ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) ∧ 𝑑𝑏 ) → ( ( 𝑎 +no 𝑑 ) ∈ ( 𝑎 +no 𝑏 ) ∧ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) )
63 ontr1 ( 𝑥 ∈ On → ( ( ( 𝑎 +no 𝑑 ) ∈ ( 𝑎 +no 𝑏 ) ∧ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) → ( 𝑎 +no 𝑑 ) ∈ 𝑥 ) )
64 52 62 63 sylc ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ∧ 𝑥 ∈ On ) ∧ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) ∧ 𝑑𝑏 ) → ( 𝑎 +no 𝑑 ) ∈ 𝑥 )
65 64 ralrimiva ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ∧ 𝑥 ∈ On ) ∧ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) → ∀ 𝑑𝑏 ( 𝑎 +no 𝑑 ) ∈ 𝑥 )
66 simpll1 ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ∧ 𝑥 ∈ On ) ∧ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) ∧ 𝑐𝑎 ) → 𝑎 ∈ On )
67 simpr ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ∧ 𝑥 ∈ On ) ∧ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) ∧ 𝑐𝑎 ) → 𝑐𝑎 )
68 onelon ( ( 𝑎 ∈ On ∧ 𝑐𝑎 ) → 𝑐 ∈ On )
69 66 67 68 syl2anc ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ∧ 𝑥 ∈ On ) ∧ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) ∧ 𝑐𝑎 ) → 𝑐 ∈ On )
70 simpll2 ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ∧ 𝑥 ∈ On ) ∧ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) ∧ 𝑐𝑎 ) → 𝑏 ∈ On )
71 69 66 70 3jca ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ∧ 𝑥 ∈ On ) ∧ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) ∧ 𝑐𝑎 ) → ( 𝑐 ∈ On ∧ 𝑎 ∈ On ∧ 𝑏 ∈ On ) )
72 naddelim ( ( 𝑐 ∈ On ∧ 𝑎 ∈ On ∧ 𝑏 ∈ On ) → ( 𝑐𝑎 → ( 𝑐 +no 𝑏 ) ∈ ( 𝑎 +no 𝑏 ) ) )
73 71 67 72 sylc ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ∧ 𝑥 ∈ On ) ∧ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) ∧ 𝑐𝑎 ) → ( 𝑐 +no 𝑏 ) ∈ ( 𝑎 +no 𝑏 ) )
74 simplr ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ∧ 𝑥 ∈ On ) ∧ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) ∧ 𝑐𝑎 ) → ( 𝑎 +no 𝑏 ) ∈ 𝑥 )
75 elunii ( ( ( 𝑐 +no 𝑏 ) ∈ ( 𝑎 +no 𝑏 ) ∧ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) → ( 𝑐 +no 𝑏 ) ∈ 𝑥 )
76 73 74 75 syl2anc ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ∧ 𝑥 ∈ On ) ∧ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) ∧ 𝑐𝑎 ) → ( 𝑐 +no 𝑏 ) ∈ 𝑥 )
77 simpll3 ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ∧ 𝑥 ∈ On ) ∧ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) ∧ 𝑐𝑎 ) → 𝑥 ∈ On )
78 eloni ( 𝑥 ∈ On → Ord 𝑥 )
79 77 78 syl ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ∧ 𝑥 ∈ On ) ∧ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) ∧ 𝑐𝑎 ) → Ord 𝑥 )
80 ordsucuniel ( Ord 𝑥 → ( ( 𝑐 +no 𝑏 ) ∈ 𝑥 ↔ suc ( 𝑐 +no 𝑏 ) ∈ 𝑥 ) )
81 79 80 syl ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ∧ 𝑥 ∈ On ) ∧ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) ∧ 𝑐𝑎 ) → ( ( 𝑐 +no 𝑏 ) ∈ 𝑥 ↔ suc ( 𝑐 +no 𝑏 ) ∈ 𝑥 ) )
82 76 81 mpbid ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ∧ 𝑥 ∈ On ) ∧ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) ∧ 𝑐𝑎 ) → suc ( 𝑐 +no 𝑏 ) ∈ 𝑥 )
83 82 ralrimiva ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ∧ 𝑥 ∈ On ) ∧ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) → ∀ 𝑐𝑎 suc ( 𝑐 +no 𝑏 ) ∈ 𝑥 )
84 65 83 jca ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ∧ 𝑥 ∈ On ) ∧ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) → ( ∀ 𝑑𝑏 ( 𝑎 +no 𝑑 ) ∈ 𝑥 ∧ ∀ 𝑐𝑎 suc ( 𝑐 +no 𝑏 ) ∈ 𝑥 ) )
85 84 ex ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ∧ 𝑥 ∈ On ) → ( ( 𝑎 +no 𝑏 ) ∈ 𝑥 → ( ∀ 𝑑𝑏 ( 𝑎 +no 𝑑 ) ∈ 𝑥 ∧ ∀ 𝑐𝑎 suc ( 𝑐 +no 𝑏 ) ∈ 𝑥 ) ) )
86 85 ad4ant124 ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) ) ∧ 𝑥 ∈ On ) → ( ( 𝑎 +no 𝑏 ) ∈ 𝑥 → ( ∀ 𝑑𝑏 ( 𝑎 +no 𝑑 ) ∈ 𝑥 ∧ ∀ 𝑐𝑎 suc ( 𝑐 +no 𝑏 ) ∈ 𝑥 ) ) )
87 86 pm4.71d ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) ) ∧ 𝑥 ∈ On ) → ( ( 𝑎 +no 𝑏 ) ∈ 𝑥 ↔ ( ( 𝑎 +no 𝑏 ) ∈ 𝑥 ∧ ( ∀ 𝑑𝑏 ( 𝑎 +no 𝑑 ) ∈ 𝑥 ∧ ∀ 𝑐𝑎 suc ( 𝑐 +no 𝑏 ) ∈ 𝑥 ) ) ) )
88 51 87 bitr4id ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) ) ∧ 𝑥 ∈ On ) → ( ( ( ( 𝑎 +no 𝑏 ) ∈ 𝑥 ∧ ∀ 𝑑𝑏 ( 𝑎 +no 𝑑 ) ∈ 𝑥 ) ∧ ∀ 𝑐𝑎 suc ( 𝑐 +no 𝑏 ) ∈ 𝑥 ) ↔ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) )
89 50 88 bitrd ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) ) ∧ 𝑥 ∈ On ) → ( ( ∀ 𝑑 ∈ suc 𝑏 ( 𝑎 +no 𝑑 ) ∈ 𝑥 ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) ∈ 𝑥 ) ↔ ( 𝑎 +no 𝑏 ) ∈ 𝑥 ) )
90 89 rabbidva ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) ) → { 𝑥 ∈ On ∣ ( ∀ 𝑑 ∈ suc 𝑏 ( 𝑎 +no 𝑑 ) ∈ 𝑥 ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) ∈ 𝑥 ) } = { 𝑥 ∈ On ∣ ( 𝑎 +no 𝑏 ) ∈ 𝑥 } )
91 90 inteqd ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) ) → { 𝑥 ∈ On ∣ ( ∀ 𝑑 ∈ suc 𝑏 ( 𝑎 +no 𝑑 ) ∈ 𝑥 ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) ∈ 𝑥 ) } = { 𝑥 ∈ On ∣ ( 𝑎 +no 𝑏 ) ∈ 𝑥 } )
92 onsuc ( 𝑏 ∈ On → suc 𝑏 ∈ On )
93 naddov2 ( ( 𝑎 ∈ On ∧ suc 𝑏 ∈ On ) → ( 𝑎 +no suc 𝑏 ) = { 𝑥 ∈ On ∣ ( ∀ 𝑑 ∈ suc 𝑏 ( 𝑎 +no 𝑑 ) ∈ 𝑥 ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) ∈ 𝑥 ) } )
94 92 93 sylan2 ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) → ( 𝑎 +no suc 𝑏 ) = { 𝑥 ∈ On ∣ ( ∀ 𝑑 ∈ suc 𝑏 ( 𝑎 +no 𝑑 ) ∈ 𝑥 ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) ∈ 𝑥 ) } )
95 94 adantr ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) ) → ( 𝑎 +no suc 𝑏 ) = { 𝑥 ∈ On ∣ ( ∀ 𝑑 ∈ suc 𝑏 ( 𝑎 +no 𝑑 ) ∈ 𝑥 ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) ∈ 𝑥 ) } )
96 naddcl ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) → ( 𝑎 +no 𝑏 ) ∈ On )
97 onsucmin ( ( 𝑎 +no 𝑏 ) ∈ On → suc ( 𝑎 +no 𝑏 ) = { 𝑥 ∈ On ∣ ( 𝑎 +no 𝑏 ) ∈ 𝑥 } )
98 96 97 syl ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) → suc ( 𝑎 +no 𝑏 ) = { 𝑥 ∈ On ∣ ( 𝑎 +no 𝑏 ) ∈ 𝑥 } )
99 98 adantr ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) ) → suc ( 𝑎 +no 𝑏 ) = { 𝑥 ∈ On ∣ ( 𝑎 +no 𝑏 ) ∈ 𝑥 } )
100 91 95 99 3eqtr4d ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) ) → ( 𝑎 +no suc 𝑏 ) = suc ( 𝑎 +no 𝑏 ) )
101 100 ex ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) → ( ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) → ( 𝑎 +no suc 𝑏 ) = suc ( 𝑎 +no 𝑏 ) ) )
102 29 101 syld ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) → ( ( ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 +no suc 𝑑 ) = suc ( 𝑐 +no 𝑑 ) ∧ ∀ 𝑐𝑎 ( 𝑐 +no suc 𝑏 ) = suc ( 𝑐 +no 𝑏 ) ∧ ∀ 𝑑𝑏 ( 𝑎 +no suc 𝑑 ) = suc ( 𝑎 +no 𝑑 ) ) → ( 𝑎 +no suc 𝑏 ) = suc ( 𝑎 +no 𝑏 ) ) )
103 5 11 16 21 27 102 on2ind ( ( 𝐴 ∈ On ∧ 𝐵 ∈ On ) → ( 𝐴 +no suc 𝐵 ) = suc ( 𝐴 +no 𝐵 ) )