Metamath Proof Explorer


Theorem nmulcom

Description: Natural multiplication commutes. (Contributed by Scott Fenton, 10-Jun-2026)

Ref Expression
Assertion nmulcom ( ( 𝐴 ∈ On ∧ 𝐵 ∈ On ) → ( 𝐴 ·no 𝐵 ) = ( 𝐵 ·no 𝐴 ) )

Proof

Step Hyp Ref Expression
1 oveq1 ( 𝑎 = 𝑐 → ( 𝑎 ·no 𝑏 ) = ( 𝑐 ·no 𝑏 ) )
2 oveq2 ( 𝑎 = 𝑐 → ( 𝑏 ·no 𝑎 ) = ( 𝑏 ·no 𝑐 ) )
3 1 2 eqeq12d ( 𝑎 = 𝑐 → ( ( 𝑎 ·no 𝑏 ) = ( 𝑏 ·no 𝑎 ) ↔ ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) ) )
4 oveq2 ( 𝑏 = 𝑑 → ( 𝑐 ·no 𝑏 ) = ( 𝑐 ·no 𝑑 ) )
5 oveq1 ( 𝑏 = 𝑑 → ( 𝑏 ·no 𝑐 ) = ( 𝑑 ·no 𝑐 ) )
6 4 5 eqeq12d ( 𝑏 = 𝑑 → ( ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) ↔ ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) ) )
7 oveq1 ( 𝑎 = 𝑐 → ( 𝑎 ·no 𝑑 ) = ( 𝑐 ·no 𝑑 ) )
8 oveq2 ( 𝑎 = 𝑐 → ( 𝑑 ·no 𝑎 ) = ( 𝑑 ·no 𝑐 ) )
9 7 8 eqeq12d ( 𝑎 = 𝑐 → ( ( 𝑎 ·no 𝑑 ) = ( 𝑑 ·no 𝑎 ) ↔ ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) ) )
10 oveq1 ( 𝑎 = 𝐴 → ( 𝑎 ·no 𝑏 ) = ( 𝐴 ·no 𝑏 ) )
11 oveq2 ( 𝑎 = 𝐴 → ( 𝑏 ·no 𝑎 ) = ( 𝑏 ·no 𝐴 ) )
12 10 11 eqeq12d ( 𝑎 = 𝐴 → ( ( 𝑎 ·no 𝑏 ) = ( 𝑏 ·no 𝑎 ) ↔ ( 𝐴 ·no 𝑏 ) = ( 𝑏 ·no 𝐴 ) ) )
13 oveq2 ( 𝑏 = 𝐵 → ( 𝐴 ·no 𝑏 ) = ( 𝐴 ·no 𝐵 ) )
14 oveq1 ( 𝑏 = 𝐵 → ( 𝑏 ·no 𝐴 ) = ( 𝐵 ·no 𝐴 ) )
15 13 14 eqeq12d ( 𝑏 = 𝐵 → ( ( 𝐴 ·no 𝑏 ) = ( 𝑏 ·no 𝐴 ) ↔ ( 𝐴 ·no 𝐵 ) = ( 𝐵 ·no 𝐴 ) ) )
16 oveq1 ( 𝑐 = 𝑧 → ( 𝑐 ·no 𝑏 ) = ( 𝑧 ·no 𝑏 ) )
17 oveq2 ( 𝑐 = 𝑧 → ( 𝑏 ·no 𝑐 ) = ( 𝑏 ·no 𝑧 ) )
18 16 17 eqeq12d ( 𝑐 = 𝑧 → ( ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) ↔ ( 𝑧 ·no 𝑏 ) = ( 𝑏 ·no 𝑧 ) ) )
19 simplr2 ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ( ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) ∧ ∀ 𝑐𝑎 ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) ∧ ∀ 𝑑𝑏 ( 𝑎 ·no 𝑑 ) = ( 𝑑 ·no 𝑎 ) ) ) ∧ ( 𝑧𝑎𝑦𝑏 ) ) → ∀ 𝑐𝑎 ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) )
20 simprl ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ( ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) ∧ ∀ 𝑐𝑎 ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) ∧ ∀ 𝑑𝑏 ( 𝑎 ·no 𝑑 ) = ( 𝑑 ·no 𝑎 ) ) ) ∧ ( 𝑧𝑎𝑦𝑏 ) ) → 𝑧𝑎 )
21 18 19 20 rspcdva ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ( ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) ∧ ∀ 𝑐𝑎 ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) ∧ ∀ 𝑑𝑏 ( 𝑎 ·no 𝑑 ) = ( 𝑑 ·no 𝑎 ) ) ) ∧ ( 𝑧𝑎𝑦𝑏 ) ) → ( 𝑧 ·no 𝑏 ) = ( 𝑏 ·no 𝑧 ) )
22 oveq2 ( 𝑑 = 𝑦 → ( 𝑎 ·no 𝑑 ) = ( 𝑎 ·no 𝑦 ) )
23 oveq1 ( 𝑑 = 𝑦 → ( 𝑑 ·no 𝑎 ) = ( 𝑦 ·no 𝑎 ) )
24 22 23 eqeq12d ( 𝑑 = 𝑦 → ( ( 𝑎 ·no 𝑑 ) = ( 𝑑 ·no 𝑎 ) ↔ ( 𝑎 ·no 𝑦 ) = ( 𝑦 ·no 𝑎 ) ) )
25 simplr3 ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ( ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) ∧ ∀ 𝑐𝑎 ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) ∧ ∀ 𝑑𝑏 ( 𝑎 ·no 𝑑 ) = ( 𝑑 ·no 𝑎 ) ) ) ∧ ( 𝑧𝑎𝑦𝑏 ) ) → ∀ 𝑑𝑏 ( 𝑎 ·no 𝑑 ) = ( 𝑑 ·no 𝑎 ) )
26 simprr ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ( ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) ∧ ∀ 𝑐𝑎 ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) ∧ ∀ 𝑑𝑏 ( 𝑎 ·no 𝑑 ) = ( 𝑑 ·no 𝑎 ) ) ) ∧ ( 𝑧𝑎𝑦𝑏 ) ) → 𝑦𝑏 )
27 24 25 26 rspcdva ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ( ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) ∧ ∀ 𝑐𝑎 ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) ∧ ∀ 𝑑𝑏 ( 𝑎 ·no 𝑑 ) = ( 𝑑 ·no 𝑎 ) ) ) ∧ ( 𝑧𝑎𝑦𝑏 ) ) → ( 𝑎 ·no 𝑦 ) = ( 𝑦 ·no 𝑎 ) )
28 21 27 oveq12d ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ( ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) ∧ ∀ 𝑐𝑎 ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) ∧ ∀ 𝑑𝑏 ( 𝑎 ·no 𝑑 ) = ( 𝑑 ·no 𝑎 ) ) ) ∧ ( 𝑧𝑎𝑦𝑏 ) ) → ( ( 𝑧 ·no 𝑏 ) +no ( 𝑎 ·no 𝑦 ) ) = ( ( 𝑏 ·no 𝑧 ) +no ( 𝑦 ·no 𝑎 ) ) )
29 simpllr ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ( ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) ∧ ∀ 𝑐𝑎 ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) ∧ ∀ 𝑑𝑏 ( 𝑎 ·no 𝑑 ) = ( 𝑑 ·no 𝑎 ) ) ) ∧ ( 𝑧𝑎𝑦𝑏 ) ) → 𝑏 ∈ On )
30 simplll ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ( ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) ∧ ∀ 𝑐𝑎 ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) ∧ ∀ 𝑑𝑏 ( 𝑎 ·no 𝑑 ) = ( 𝑑 ·no 𝑎 ) ) ) ∧ ( 𝑧𝑎𝑦𝑏 ) ) → 𝑎 ∈ On )
31 onelon ( ( 𝑎 ∈ On ∧ 𝑧𝑎 ) → 𝑧 ∈ On )
32 30 20 31 syl2anc ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ( ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) ∧ ∀ 𝑐𝑎 ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) ∧ ∀ 𝑑𝑏 ( 𝑎 ·no 𝑑 ) = ( 𝑑 ·no 𝑎 ) ) ) ∧ ( 𝑧𝑎𝑦𝑏 ) ) → 𝑧 ∈ On )
33 nmulcl ( ( 𝑏 ∈ On ∧ 𝑧 ∈ On ) → ( 𝑏 ·no 𝑧 ) ∈ On )
34 29 32 33 syl2anc ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ( ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) ∧ ∀ 𝑐𝑎 ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) ∧ ∀ 𝑑𝑏 ( 𝑎 ·no 𝑑 ) = ( 𝑑 ·no 𝑎 ) ) ) ∧ ( 𝑧𝑎𝑦𝑏 ) ) → ( 𝑏 ·no 𝑧 ) ∈ On )
35 onelon ( ( 𝑏 ∈ On ∧ 𝑦𝑏 ) → 𝑦 ∈ On )
36 29 26 35 syl2anc ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ( ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) ∧ ∀ 𝑐𝑎 ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) ∧ ∀ 𝑑𝑏 ( 𝑎 ·no 𝑑 ) = ( 𝑑 ·no 𝑎 ) ) ) ∧ ( 𝑧𝑎𝑦𝑏 ) ) → 𝑦 ∈ On )
37 nmulcl ( ( 𝑦 ∈ On ∧ 𝑎 ∈ On ) → ( 𝑦 ·no 𝑎 ) ∈ On )
38 36 30 37 syl2anc ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ( ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) ∧ ∀ 𝑐𝑎 ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) ∧ ∀ 𝑑𝑏 ( 𝑎 ·no 𝑑 ) = ( 𝑑 ·no 𝑎 ) ) ) ∧ ( 𝑧𝑎𝑦𝑏 ) ) → ( 𝑦 ·no 𝑎 ) ∈ On )
39 naddcom ( ( ( 𝑏 ·no 𝑧 ) ∈ On ∧ ( 𝑦 ·no 𝑎 ) ∈ On ) → ( ( 𝑏 ·no 𝑧 ) +no ( 𝑦 ·no 𝑎 ) ) = ( ( 𝑦 ·no 𝑎 ) +no ( 𝑏 ·no 𝑧 ) ) )
40 34 38 39 syl2anc ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ( ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) ∧ ∀ 𝑐𝑎 ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) ∧ ∀ 𝑑𝑏 ( 𝑎 ·no 𝑑 ) = ( 𝑑 ·no 𝑎 ) ) ) ∧ ( 𝑧𝑎𝑦𝑏 ) ) → ( ( 𝑏 ·no 𝑧 ) +no ( 𝑦 ·no 𝑎 ) ) = ( ( 𝑦 ·no 𝑎 ) +no ( 𝑏 ·no 𝑧 ) ) )
41 28 40 eqtrd ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ( ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) ∧ ∀ 𝑐𝑎 ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) ∧ ∀ 𝑑𝑏 ( 𝑎 ·no 𝑑 ) = ( 𝑑 ·no 𝑎 ) ) ) ∧ ( 𝑧𝑎𝑦𝑏 ) ) → ( ( 𝑧 ·no 𝑏 ) +no ( 𝑎 ·no 𝑦 ) ) = ( ( 𝑦 ·no 𝑎 ) +no ( 𝑏 ·no 𝑧 ) ) )
42 oveq1 ( 𝑐 = 𝑧 → ( 𝑐 ·no 𝑑 ) = ( 𝑧 ·no 𝑑 ) )
43 oveq2 ( 𝑐 = 𝑧 → ( 𝑑 ·no 𝑐 ) = ( 𝑑 ·no 𝑧 ) )
44 42 43 eqeq12d ( 𝑐 = 𝑧 → ( ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) ↔ ( 𝑧 ·no 𝑑 ) = ( 𝑑 ·no 𝑧 ) ) )
45 oveq2 ( 𝑑 = 𝑦 → ( 𝑧 ·no 𝑑 ) = ( 𝑧 ·no 𝑦 ) )
46 oveq1 ( 𝑑 = 𝑦 → ( 𝑑 ·no 𝑧 ) = ( 𝑦 ·no 𝑧 ) )
47 45 46 eqeq12d ( 𝑑 = 𝑦 → ( ( 𝑧 ·no 𝑑 ) = ( 𝑑 ·no 𝑧 ) ↔ ( 𝑧 ·no 𝑦 ) = ( 𝑦 ·no 𝑧 ) ) )
48 simplr1 ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ( ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) ∧ ∀ 𝑐𝑎 ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) ∧ ∀ 𝑑𝑏 ( 𝑎 ·no 𝑑 ) = ( 𝑑 ·no 𝑎 ) ) ) ∧ ( 𝑧𝑎𝑦𝑏 ) ) → ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) )
49 44 47 48 20 26 rspc2dv ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ( ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) ∧ ∀ 𝑐𝑎 ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) ∧ ∀ 𝑑𝑏 ( 𝑎 ·no 𝑑 ) = ( 𝑑 ·no 𝑎 ) ) ) ∧ ( 𝑧𝑎𝑦𝑏 ) ) → ( 𝑧 ·no 𝑦 ) = ( 𝑦 ·no 𝑧 ) )
50 49 oveq2d ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ( ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) ∧ ∀ 𝑐𝑎 ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) ∧ ∀ 𝑑𝑏 ( 𝑎 ·no 𝑑 ) = ( 𝑑 ·no 𝑎 ) ) ) ∧ ( 𝑧𝑎𝑦𝑏 ) ) → ( 𝑥 +no ( 𝑧 ·no 𝑦 ) ) = ( 𝑥 +no ( 𝑦 ·no 𝑧 ) ) )
51 41 50 eleq12d ( ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ( ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) ∧ ∀ 𝑐𝑎 ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) ∧ ∀ 𝑑𝑏 ( 𝑎 ·no 𝑑 ) = ( 𝑑 ·no 𝑎 ) ) ) ∧ ( 𝑧𝑎𝑦𝑏 ) ) → ( ( ( 𝑧 ·no 𝑏 ) +no ( 𝑎 ·no 𝑦 ) ) ∈ ( 𝑥 +no ( 𝑧 ·no 𝑦 ) ) ↔ ( ( 𝑦 ·no 𝑎 ) +no ( 𝑏 ·no 𝑧 ) ) ∈ ( 𝑥 +no ( 𝑦 ·no 𝑧 ) ) ) )
52 51 2ralbidva ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ( ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) ∧ ∀ 𝑐𝑎 ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) ∧ ∀ 𝑑𝑏 ( 𝑎 ·no 𝑑 ) = ( 𝑑 ·no 𝑎 ) ) ) → ( ∀ 𝑧𝑎𝑦𝑏 ( ( 𝑧 ·no 𝑏 ) +no ( 𝑎 ·no 𝑦 ) ) ∈ ( 𝑥 +no ( 𝑧 ·no 𝑦 ) ) ↔ ∀ 𝑧𝑎𝑦𝑏 ( ( 𝑦 ·no 𝑎 ) +no ( 𝑏 ·no 𝑧 ) ) ∈ ( 𝑥 +no ( 𝑦 ·no 𝑧 ) ) ) )
53 ralcom ( ∀ 𝑧𝑎𝑦𝑏 ( ( 𝑦 ·no 𝑎 ) +no ( 𝑏 ·no 𝑧 ) ) ∈ ( 𝑥 +no ( 𝑦 ·no 𝑧 ) ) ↔ ∀ 𝑦𝑏𝑧𝑎 ( ( 𝑦 ·no 𝑎 ) +no ( 𝑏 ·no 𝑧 ) ) ∈ ( 𝑥 +no ( 𝑦 ·no 𝑧 ) ) )
54 52 53 bitrdi ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ( ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) ∧ ∀ 𝑐𝑎 ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) ∧ ∀ 𝑑𝑏 ( 𝑎 ·no 𝑑 ) = ( 𝑑 ·no 𝑎 ) ) ) → ( ∀ 𝑧𝑎𝑦𝑏 ( ( 𝑧 ·no 𝑏 ) +no ( 𝑎 ·no 𝑦 ) ) ∈ ( 𝑥 +no ( 𝑧 ·no 𝑦 ) ) ↔ ∀ 𝑦𝑏𝑧𝑎 ( ( 𝑦 ·no 𝑎 ) +no ( 𝑏 ·no 𝑧 ) ) ∈ ( 𝑥 +no ( 𝑦 ·no 𝑧 ) ) ) )
55 54 rabbidv ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ( ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) ∧ ∀ 𝑐𝑎 ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) ∧ ∀ 𝑑𝑏 ( 𝑎 ·no 𝑑 ) = ( 𝑑 ·no 𝑎 ) ) ) → { 𝑥 ∈ On ∣ ∀ 𝑧𝑎𝑦𝑏 ( ( 𝑧 ·no 𝑏 ) +no ( 𝑎 ·no 𝑦 ) ) ∈ ( 𝑥 +no ( 𝑧 ·no 𝑦 ) ) } = { 𝑥 ∈ On ∣ ∀ 𝑦𝑏𝑧𝑎 ( ( 𝑦 ·no 𝑎 ) +no ( 𝑏 ·no 𝑧 ) ) ∈ ( 𝑥 +no ( 𝑦 ·no 𝑧 ) ) } )
56 55 inteqd ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ( ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) ∧ ∀ 𝑐𝑎 ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) ∧ ∀ 𝑑𝑏 ( 𝑎 ·no 𝑑 ) = ( 𝑑 ·no 𝑎 ) ) ) → { 𝑥 ∈ On ∣ ∀ 𝑧𝑎𝑦𝑏 ( ( 𝑧 ·no 𝑏 ) +no ( 𝑎 ·no 𝑦 ) ) ∈ ( 𝑥 +no ( 𝑧 ·no 𝑦 ) ) } = { 𝑥 ∈ On ∣ ∀ 𝑦𝑏𝑧𝑎 ( ( 𝑦 ·no 𝑎 ) +no ( 𝑏 ·no 𝑧 ) ) ∈ ( 𝑥 +no ( 𝑦 ·no 𝑧 ) ) } )
57 nmulval ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) → ( 𝑎 ·no 𝑏 ) = { 𝑥 ∈ On ∣ ∀ 𝑧𝑎𝑦𝑏 ( ( 𝑧 ·no 𝑏 ) +no ( 𝑎 ·no 𝑦 ) ) ∈ ( 𝑥 +no ( 𝑧 ·no 𝑦 ) ) } )
58 57 adantr ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ( ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) ∧ ∀ 𝑐𝑎 ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) ∧ ∀ 𝑑𝑏 ( 𝑎 ·no 𝑑 ) = ( 𝑑 ·no 𝑎 ) ) ) → ( 𝑎 ·no 𝑏 ) = { 𝑥 ∈ On ∣ ∀ 𝑧𝑎𝑦𝑏 ( ( 𝑧 ·no 𝑏 ) +no ( 𝑎 ·no 𝑦 ) ) ∈ ( 𝑥 +no ( 𝑧 ·no 𝑦 ) ) } )
59 nmulval ( ( 𝑏 ∈ On ∧ 𝑎 ∈ On ) → ( 𝑏 ·no 𝑎 ) = { 𝑥 ∈ On ∣ ∀ 𝑦𝑏𝑧𝑎 ( ( 𝑦 ·no 𝑎 ) +no ( 𝑏 ·no 𝑧 ) ) ∈ ( 𝑥 +no ( 𝑦 ·no 𝑧 ) ) } )
60 59 ancoms ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) → ( 𝑏 ·no 𝑎 ) = { 𝑥 ∈ On ∣ ∀ 𝑦𝑏𝑧𝑎 ( ( 𝑦 ·no 𝑎 ) +no ( 𝑏 ·no 𝑧 ) ) ∈ ( 𝑥 +no ( 𝑦 ·no 𝑧 ) ) } )
61 60 adantr ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ( ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) ∧ ∀ 𝑐𝑎 ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) ∧ ∀ 𝑑𝑏 ( 𝑎 ·no 𝑑 ) = ( 𝑑 ·no 𝑎 ) ) ) → ( 𝑏 ·no 𝑎 ) = { 𝑥 ∈ On ∣ ∀ 𝑦𝑏𝑧𝑎 ( ( 𝑦 ·no 𝑎 ) +no ( 𝑏 ·no 𝑧 ) ) ∈ ( 𝑥 +no ( 𝑦 ·no 𝑧 ) ) } )
62 56 58 61 3eqtr4d ( ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) ∧ ( ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) ∧ ∀ 𝑐𝑎 ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) ∧ ∀ 𝑑𝑏 ( 𝑎 ·no 𝑑 ) = ( 𝑑 ·no 𝑎 ) ) ) → ( 𝑎 ·no 𝑏 ) = ( 𝑏 ·no 𝑎 ) )
63 62 ex ( ( 𝑎 ∈ On ∧ 𝑏 ∈ On ) → ( ( ∀ 𝑐𝑎𝑑𝑏 ( 𝑐 ·no 𝑑 ) = ( 𝑑 ·no 𝑐 ) ∧ ∀ 𝑐𝑎 ( 𝑐 ·no 𝑏 ) = ( 𝑏 ·no 𝑐 ) ∧ ∀ 𝑑𝑏 ( 𝑎 ·no 𝑑 ) = ( 𝑑 ·no 𝑎 ) ) → ( 𝑎 ·no 𝑏 ) = ( 𝑏 ·no 𝑎 ) ) )
64 3 6 9 12 15 63 on2ind ( ( 𝐴 ∈ On ∧ 𝐵 ∈ On ) → ( 𝐴 ·no 𝐵 ) = ( 𝐵 ·no 𝐴 ) )