| Step | Hyp | Ref | Expression | 
						
							| 1 |  | oveq2 | ⊢ ( 𝑥  =  ∅  →  ( ( 𝐴  ·o  𝐵 )  ·o  𝑥 )  =  ( ( 𝐴  ·o  𝐵 )  ·o  ∅ ) ) | 
						
							| 2 |  | oveq2 | ⊢ ( 𝑥  =  ∅  →  ( 𝐵  ·o  𝑥 )  =  ( 𝐵  ·o  ∅ ) ) | 
						
							| 3 | 2 | oveq2d | ⊢ ( 𝑥  =  ∅  →  ( 𝐴  ·o  ( 𝐵  ·o  𝑥 ) )  =  ( 𝐴  ·o  ( 𝐵  ·o  ∅ ) ) ) | 
						
							| 4 | 1 3 | eqeq12d | ⊢ ( 𝑥  =  ∅  →  ( ( ( 𝐴  ·o  𝐵 )  ·o  𝑥 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑥 ) )  ↔  ( ( 𝐴  ·o  𝐵 )  ·o  ∅ )  =  ( 𝐴  ·o  ( 𝐵  ·o  ∅ ) ) ) ) | 
						
							| 5 |  | oveq2 | ⊢ ( 𝑥  =  𝑦  →  ( ( 𝐴  ·o  𝐵 )  ·o  𝑥 )  =  ( ( 𝐴  ·o  𝐵 )  ·o  𝑦 ) ) | 
						
							| 6 |  | oveq2 | ⊢ ( 𝑥  =  𝑦  →  ( 𝐵  ·o  𝑥 )  =  ( 𝐵  ·o  𝑦 ) ) | 
						
							| 7 | 6 | oveq2d | ⊢ ( 𝑥  =  𝑦  →  ( 𝐴  ·o  ( 𝐵  ·o  𝑥 ) )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) ) ) | 
						
							| 8 | 5 7 | eqeq12d | ⊢ ( 𝑥  =  𝑦  →  ( ( ( 𝐴  ·o  𝐵 )  ·o  𝑥 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑥 ) )  ↔  ( ( 𝐴  ·o  𝐵 )  ·o  𝑦 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) ) ) ) | 
						
							| 9 |  | oveq2 | ⊢ ( 𝑥  =  suc  𝑦  →  ( ( 𝐴  ·o  𝐵 )  ·o  𝑥 )  =  ( ( 𝐴  ·o  𝐵 )  ·o  suc  𝑦 ) ) | 
						
							| 10 |  | oveq2 | ⊢ ( 𝑥  =  suc  𝑦  →  ( 𝐵  ·o  𝑥 )  =  ( 𝐵  ·o  suc  𝑦 ) ) | 
						
							| 11 | 10 | oveq2d | ⊢ ( 𝑥  =  suc  𝑦  →  ( 𝐴  ·o  ( 𝐵  ·o  𝑥 ) )  =  ( 𝐴  ·o  ( 𝐵  ·o  suc  𝑦 ) ) ) | 
						
							| 12 | 9 11 | eqeq12d | ⊢ ( 𝑥  =  suc  𝑦  →  ( ( ( 𝐴  ·o  𝐵 )  ·o  𝑥 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑥 ) )  ↔  ( ( 𝐴  ·o  𝐵 )  ·o  suc  𝑦 )  =  ( 𝐴  ·o  ( 𝐵  ·o  suc  𝑦 ) ) ) ) | 
						
							| 13 |  | oveq2 | ⊢ ( 𝑥  =  𝐶  →  ( ( 𝐴  ·o  𝐵 )  ·o  𝑥 )  =  ( ( 𝐴  ·o  𝐵 )  ·o  𝐶 ) ) | 
						
							| 14 |  | oveq2 | ⊢ ( 𝑥  =  𝐶  →  ( 𝐵  ·o  𝑥 )  =  ( 𝐵  ·o  𝐶 ) ) | 
						
							| 15 | 14 | oveq2d | ⊢ ( 𝑥  =  𝐶  →  ( 𝐴  ·o  ( 𝐵  ·o  𝑥 ) )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝐶 ) ) ) | 
						
							| 16 | 13 15 | eqeq12d | ⊢ ( 𝑥  =  𝐶  →  ( ( ( 𝐴  ·o  𝐵 )  ·o  𝑥 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑥 ) )  ↔  ( ( 𝐴  ·o  𝐵 )  ·o  𝐶 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝐶 ) ) ) ) | 
						
							| 17 |  | omcl | ⊢ ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On )  →  ( 𝐴  ·o  𝐵 )  ∈  On ) | 
						
							| 18 |  | om0 | ⊢ ( ( 𝐴  ·o  𝐵 )  ∈  On  →  ( ( 𝐴  ·o  𝐵 )  ·o  ∅ )  =  ∅ ) | 
						
							| 19 | 17 18 | syl | ⊢ ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On )  →  ( ( 𝐴  ·o  𝐵 )  ·o  ∅ )  =  ∅ ) | 
						
							| 20 |  | om0 | ⊢ ( 𝐵  ∈  On  →  ( 𝐵  ·o  ∅ )  =  ∅ ) | 
						
							| 21 | 20 | oveq2d | ⊢ ( 𝐵  ∈  On  →  ( 𝐴  ·o  ( 𝐵  ·o  ∅ ) )  =  ( 𝐴  ·o  ∅ ) ) | 
						
							| 22 |  | om0 | ⊢ ( 𝐴  ∈  On  →  ( 𝐴  ·o  ∅ )  =  ∅ ) | 
						
							| 23 | 21 22 | sylan9eqr | ⊢ ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On )  →  ( 𝐴  ·o  ( 𝐵  ·o  ∅ ) )  =  ∅ ) | 
						
							| 24 | 19 23 | eqtr4d | ⊢ ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On )  →  ( ( 𝐴  ·o  𝐵 )  ·o  ∅ )  =  ( 𝐴  ·o  ( 𝐵  ·o  ∅ ) ) ) | 
						
							| 25 |  | oveq1 | ⊢ ( ( ( 𝐴  ·o  𝐵 )  ·o  𝑦 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  →  ( ( ( 𝐴  ·o  𝐵 )  ·o  𝑦 )  +o  ( 𝐴  ·o  𝐵 ) )  =  ( ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  +o  ( 𝐴  ·o  𝐵 ) ) ) | 
						
							| 26 |  | omsuc | ⊢ ( ( ( 𝐴  ·o  𝐵 )  ∈  On  ∧  𝑦  ∈  On )  →  ( ( 𝐴  ·o  𝐵 )  ·o  suc  𝑦 )  =  ( ( ( 𝐴  ·o  𝐵 )  ·o  𝑦 )  +o  ( 𝐴  ·o  𝐵 ) ) ) | 
						
							| 27 | 17 26 | stoic3 | ⊢ ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝑦  ∈  On )  →  ( ( 𝐴  ·o  𝐵 )  ·o  suc  𝑦 )  =  ( ( ( 𝐴  ·o  𝐵 )  ·o  𝑦 )  +o  ( 𝐴  ·o  𝐵 ) ) ) | 
						
							| 28 |  | omsuc | ⊢ ( ( 𝐵  ∈  On  ∧  𝑦  ∈  On )  →  ( 𝐵  ·o  suc  𝑦 )  =  ( ( 𝐵  ·o  𝑦 )  +o  𝐵 ) ) | 
						
							| 29 | 28 | 3adant1 | ⊢ ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝑦  ∈  On )  →  ( 𝐵  ·o  suc  𝑦 )  =  ( ( 𝐵  ·o  𝑦 )  +o  𝐵 ) ) | 
						
							| 30 | 29 | oveq2d | ⊢ ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝑦  ∈  On )  →  ( 𝐴  ·o  ( 𝐵  ·o  suc  𝑦 ) )  =  ( 𝐴  ·o  ( ( 𝐵  ·o  𝑦 )  +o  𝐵 ) ) ) | 
						
							| 31 |  | omcl | ⊢ ( ( 𝐵  ∈  On  ∧  𝑦  ∈  On )  →  ( 𝐵  ·o  𝑦 )  ∈  On ) | 
						
							| 32 |  | odi | ⊢ ( ( 𝐴  ∈  On  ∧  ( 𝐵  ·o  𝑦 )  ∈  On  ∧  𝐵  ∈  On )  →  ( 𝐴  ·o  ( ( 𝐵  ·o  𝑦 )  +o  𝐵 ) )  =  ( ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  +o  ( 𝐴  ·o  𝐵 ) ) ) | 
						
							| 33 | 31 32 | syl3an2 | ⊢ ( ( 𝐴  ∈  On  ∧  ( 𝐵  ∈  On  ∧  𝑦  ∈  On )  ∧  𝐵  ∈  On )  →  ( 𝐴  ·o  ( ( 𝐵  ·o  𝑦 )  +o  𝐵 ) )  =  ( ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  +o  ( 𝐴  ·o  𝐵 ) ) ) | 
						
							| 34 | 33 | 3exp | ⊢ ( 𝐴  ∈  On  →  ( ( 𝐵  ∈  On  ∧  𝑦  ∈  On )  →  ( 𝐵  ∈  On  →  ( 𝐴  ·o  ( ( 𝐵  ·o  𝑦 )  +o  𝐵 ) )  =  ( ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  +o  ( 𝐴  ·o  𝐵 ) ) ) ) ) | 
						
							| 35 | 34 | expd | ⊢ ( 𝐴  ∈  On  →  ( 𝐵  ∈  On  →  ( 𝑦  ∈  On  →  ( 𝐵  ∈  On  →  ( 𝐴  ·o  ( ( 𝐵  ·o  𝑦 )  +o  𝐵 ) )  =  ( ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  +o  ( 𝐴  ·o  𝐵 ) ) ) ) ) ) | 
						
							| 36 | 35 | com34 | ⊢ ( 𝐴  ∈  On  →  ( 𝐵  ∈  On  →  ( 𝐵  ∈  On  →  ( 𝑦  ∈  On  →  ( 𝐴  ·o  ( ( 𝐵  ·o  𝑦 )  +o  𝐵 ) )  =  ( ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  +o  ( 𝐴  ·o  𝐵 ) ) ) ) ) ) | 
						
							| 37 | 36 | pm2.43d | ⊢ ( 𝐴  ∈  On  →  ( 𝐵  ∈  On  →  ( 𝑦  ∈  On  →  ( 𝐴  ·o  ( ( 𝐵  ·o  𝑦 )  +o  𝐵 ) )  =  ( ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  +o  ( 𝐴  ·o  𝐵 ) ) ) ) ) | 
						
							| 38 | 37 | 3imp | ⊢ ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝑦  ∈  On )  →  ( 𝐴  ·o  ( ( 𝐵  ·o  𝑦 )  +o  𝐵 ) )  =  ( ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  +o  ( 𝐴  ·o  𝐵 ) ) ) | 
						
							| 39 | 30 38 | eqtrd | ⊢ ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝑦  ∈  On )  →  ( 𝐴  ·o  ( 𝐵  ·o  suc  𝑦 ) )  =  ( ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  +o  ( 𝐴  ·o  𝐵 ) ) ) | 
						
							| 40 | 27 39 | eqeq12d | ⊢ ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝑦  ∈  On )  →  ( ( ( 𝐴  ·o  𝐵 )  ·o  suc  𝑦 )  =  ( 𝐴  ·o  ( 𝐵  ·o  suc  𝑦 ) )  ↔  ( ( ( 𝐴  ·o  𝐵 )  ·o  𝑦 )  +o  ( 𝐴  ·o  𝐵 ) )  =  ( ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  +o  ( 𝐴  ·o  𝐵 ) ) ) ) | 
						
							| 41 | 25 40 | imbitrrid | ⊢ ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝑦  ∈  On )  →  ( ( ( 𝐴  ·o  𝐵 )  ·o  𝑦 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  →  ( ( 𝐴  ·o  𝐵 )  ·o  suc  𝑦 )  =  ( 𝐴  ·o  ( 𝐵  ·o  suc  𝑦 ) ) ) ) | 
						
							| 42 | 41 | 3exp | ⊢ ( 𝐴  ∈  On  →  ( 𝐵  ∈  On  →  ( 𝑦  ∈  On  →  ( ( ( 𝐴  ·o  𝐵 )  ·o  𝑦 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  →  ( ( 𝐴  ·o  𝐵 )  ·o  suc  𝑦 )  =  ( 𝐴  ·o  ( 𝐵  ·o  suc  𝑦 ) ) ) ) ) ) | 
						
							| 43 | 42 | com3r | ⊢ ( 𝑦  ∈  On  →  ( 𝐴  ∈  On  →  ( 𝐵  ∈  On  →  ( ( ( 𝐴  ·o  𝐵 )  ·o  𝑦 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  →  ( ( 𝐴  ·o  𝐵 )  ·o  suc  𝑦 )  =  ( 𝐴  ·o  ( 𝐵  ·o  suc  𝑦 ) ) ) ) ) ) | 
						
							| 44 | 43 | impd | ⊢ ( 𝑦  ∈  On  →  ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On )  →  ( ( ( 𝐴  ·o  𝐵 )  ·o  𝑦 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  →  ( ( 𝐴  ·o  𝐵 )  ·o  suc  𝑦 )  =  ( 𝐴  ·o  ( 𝐵  ·o  suc  𝑦 ) ) ) ) ) | 
						
							| 45 | 17 | ancoms | ⊢ ( ( 𝐵  ∈  On  ∧  𝐴  ∈  On )  →  ( 𝐴  ·o  𝐵 )  ∈  On ) | 
						
							| 46 |  | vex | ⊢ 𝑥  ∈  V | 
						
							| 47 |  | omlim | ⊢ ( ( ( 𝐴  ·o  𝐵 )  ∈  On  ∧  ( 𝑥  ∈  V  ∧  Lim  𝑥 ) )  →  ( ( 𝐴  ·o  𝐵 )  ·o  𝑥 )  =  ∪  𝑦  ∈  𝑥 ( ( 𝐴  ·o  𝐵 )  ·o  𝑦 ) ) | 
						
							| 48 | 46 47 | mpanr1 | ⊢ ( ( ( 𝐴  ·o  𝐵 )  ∈  On  ∧  Lim  𝑥 )  →  ( ( 𝐴  ·o  𝐵 )  ·o  𝑥 )  =  ∪  𝑦  ∈  𝑥 ( ( 𝐴  ·o  𝐵 )  ·o  𝑦 ) ) | 
						
							| 49 | 45 48 | sylan | ⊢ ( ( ( 𝐵  ∈  On  ∧  𝐴  ∈  On )  ∧  Lim  𝑥 )  →  ( ( 𝐴  ·o  𝐵 )  ·o  𝑥 )  =  ∪  𝑦  ∈  𝑥 ( ( 𝐴  ·o  𝐵 )  ·o  𝑦 ) ) | 
						
							| 50 | 49 | an32s | ⊢ ( ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  ∧  𝐴  ∈  On )  →  ( ( 𝐴  ·o  𝐵 )  ·o  𝑥 )  =  ∪  𝑦  ∈  𝑥 ( ( 𝐴  ·o  𝐵 )  ·o  𝑦 ) ) | 
						
							| 51 | 50 | ad2antrr | ⊢ ( ( ( ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  ∧  𝐴  ∈  On )  ∧  ∅  ∈  𝐵 )  ∧  ∀ 𝑦  ∈  𝑥 ( ( 𝐴  ·o  𝐵 )  ·o  𝑦 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) ) )  →  ( ( 𝐴  ·o  𝐵 )  ·o  𝑥 )  =  ∪  𝑦  ∈  𝑥 ( ( 𝐴  ·o  𝐵 )  ·o  𝑦 ) ) | 
						
							| 52 |  | iuneq2 | ⊢ ( ∀ 𝑦  ∈  𝑥 ( ( 𝐴  ·o  𝐵 )  ·o  𝑦 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  →  ∪  𝑦  ∈  𝑥 ( ( 𝐴  ·o  𝐵 )  ·o  𝑦 )  =  ∪  𝑦  ∈  𝑥 ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) ) ) | 
						
							| 53 |  | limelon | ⊢ ( ( 𝑥  ∈  V  ∧  Lim  𝑥 )  →  𝑥  ∈  On ) | 
						
							| 54 | 46 53 | mpan | ⊢ ( Lim  𝑥  →  𝑥  ∈  On ) | 
						
							| 55 | 54 | anim1i | ⊢ ( ( Lim  𝑥  ∧  𝐵  ∈  On )  →  ( 𝑥  ∈  On  ∧  𝐵  ∈  On ) ) | 
						
							| 56 | 55 | ancoms | ⊢ ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  →  ( 𝑥  ∈  On  ∧  𝐵  ∈  On ) ) | 
						
							| 57 |  | omordi | ⊢ ( ( ( 𝑥  ∈  On  ∧  𝐵  ∈  On )  ∧  ∅  ∈  𝐵 )  →  ( 𝑦  ∈  𝑥  →  ( 𝐵  ·o  𝑦 )  ∈  ( 𝐵  ·o  𝑥 ) ) ) | 
						
							| 58 | 56 57 | sylan | ⊢ ( ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  ∧  ∅  ∈  𝐵 )  →  ( 𝑦  ∈  𝑥  →  ( 𝐵  ·o  𝑦 )  ∈  ( 𝐵  ·o  𝑥 ) ) ) | 
						
							| 59 |  | ssid | ⊢ ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  ⊆  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) ) | 
						
							| 60 |  | oveq2 | ⊢ ( 𝑧  =  ( 𝐵  ·o  𝑦 )  →  ( 𝐴  ·o  𝑧 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) ) ) | 
						
							| 61 | 60 | sseq2d | ⊢ ( 𝑧  =  ( 𝐵  ·o  𝑦 )  →  ( ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  ⊆  ( 𝐴  ·o  𝑧 )  ↔  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  ⊆  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) ) ) ) | 
						
							| 62 | 61 | rspcev | ⊢ ( ( ( 𝐵  ·o  𝑦 )  ∈  ( 𝐵  ·o  𝑥 )  ∧  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  ⊆  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) ) )  →  ∃ 𝑧  ∈  ( 𝐵  ·o  𝑥 ) ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  ⊆  ( 𝐴  ·o  𝑧 ) ) | 
						
							| 63 | 59 62 | mpan2 | ⊢ ( ( 𝐵  ·o  𝑦 )  ∈  ( 𝐵  ·o  𝑥 )  →  ∃ 𝑧  ∈  ( 𝐵  ·o  𝑥 ) ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  ⊆  ( 𝐴  ·o  𝑧 ) ) | 
						
							| 64 | 58 63 | syl6 | ⊢ ( ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  ∧  ∅  ∈  𝐵 )  →  ( 𝑦  ∈  𝑥  →  ∃ 𝑧  ∈  ( 𝐵  ·o  𝑥 ) ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  ⊆  ( 𝐴  ·o  𝑧 ) ) ) | 
						
							| 65 | 64 | ralrimiv | ⊢ ( ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  ∧  ∅  ∈  𝐵 )  →  ∀ 𝑦  ∈  𝑥 ∃ 𝑧  ∈  ( 𝐵  ·o  𝑥 ) ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  ⊆  ( 𝐴  ·o  𝑧 ) ) | 
						
							| 66 |  | iunss2 | ⊢ ( ∀ 𝑦  ∈  𝑥 ∃ 𝑧  ∈  ( 𝐵  ·o  𝑥 ) ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  ⊆  ( 𝐴  ·o  𝑧 )  →  ∪  𝑦  ∈  𝑥 ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  ⊆  ∪  𝑧  ∈  ( 𝐵  ·o  𝑥 ) ( 𝐴  ·o  𝑧 ) ) | 
						
							| 67 | 65 66 | syl | ⊢ ( ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  ∧  ∅  ∈  𝐵 )  →  ∪  𝑦  ∈  𝑥 ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  ⊆  ∪  𝑧  ∈  ( 𝐵  ·o  𝑥 ) ( 𝐴  ·o  𝑧 ) ) | 
						
							| 68 | 67 | adantlr | ⊢ ( ( ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  ∧  𝐴  ∈  On )  ∧  ∅  ∈  𝐵 )  →  ∪  𝑦  ∈  𝑥 ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  ⊆  ∪  𝑧  ∈  ( 𝐵  ·o  𝑥 ) ( 𝐴  ·o  𝑧 ) ) | 
						
							| 69 |  | omcl | ⊢ ( ( 𝐵  ∈  On  ∧  𝑥  ∈  On )  →  ( 𝐵  ·o  𝑥 )  ∈  On ) | 
						
							| 70 | 54 69 | sylan2 | ⊢ ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  →  ( 𝐵  ·o  𝑥 )  ∈  On ) | 
						
							| 71 |  | onelon | ⊢ ( ( ( 𝐵  ·o  𝑥 )  ∈  On  ∧  𝑧  ∈  ( 𝐵  ·o  𝑥 ) )  →  𝑧  ∈  On ) | 
						
							| 72 | 70 71 | sylan | ⊢ ( ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  ∧  𝑧  ∈  ( 𝐵  ·o  𝑥 ) )  →  𝑧  ∈  On ) | 
						
							| 73 | 72 | adantlr | ⊢ ( ( ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  ∧  𝐴  ∈  On )  ∧  𝑧  ∈  ( 𝐵  ·o  𝑥 ) )  →  𝑧  ∈  On ) | 
						
							| 74 |  | omordlim | ⊢ ( ( ( 𝐵  ∈  On  ∧  ( 𝑥  ∈  V  ∧  Lim  𝑥 ) )  ∧  𝑧  ∈  ( 𝐵  ·o  𝑥 ) )  →  ∃ 𝑦  ∈  𝑥 𝑧  ∈  ( 𝐵  ·o  𝑦 ) ) | 
						
							| 75 | 74 | ex | ⊢ ( ( 𝐵  ∈  On  ∧  ( 𝑥  ∈  V  ∧  Lim  𝑥 ) )  →  ( 𝑧  ∈  ( 𝐵  ·o  𝑥 )  →  ∃ 𝑦  ∈  𝑥 𝑧  ∈  ( 𝐵  ·o  𝑦 ) ) ) | 
						
							| 76 | 46 75 | mpanr1 | ⊢ ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  →  ( 𝑧  ∈  ( 𝐵  ·o  𝑥 )  →  ∃ 𝑦  ∈  𝑥 𝑧  ∈  ( 𝐵  ·o  𝑦 ) ) ) | 
						
							| 77 | 76 | ad2antlr | ⊢ ( ( ( 𝑧  ∈  On  ∧  ( 𝐵  ∈  On  ∧  Lim  𝑥 ) )  ∧  𝐴  ∈  On )  →  ( 𝑧  ∈  ( 𝐵  ·o  𝑥 )  →  ∃ 𝑦  ∈  𝑥 𝑧  ∈  ( 𝐵  ·o  𝑦 ) ) ) | 
						
							| 78 |  | onelon | ⊢ ( ( 𝑥  ∈  On  ∧  𝑦  ∈  𝑥 )  →  𝑦  ∈  On ) | 
						
							| 79 | 54 78 | sylan | ⊢ ( ( Lim  𝑥  ∧  𝑦  ∈  𝑥 )  →  𝑦  ∈  On ) | 
						
							| 80 | 79 31 | sylan2 | ⊢ ( ( 𝐵  ∈  On  ∧  ( Lim  𝑥  ∧  𝑦  ∈  𝑥 ) )  →  ( 𝐵  ·o  𝑦 )  ∈  On ) | 
						
							| 81 |  | onelss | ⊢ ( ( 𝐵  ·o  𝑦 )  ∈  On  →  ( 𝑧  ∈  ( 𝐵  ·o  𝑦 )  →  𝑧  ⊆  ( 𝐵  ·o  𝑦 ) ) ) | 
						
							| 82 | 81 | 3ad2ant2 | ⊢ ( ( 𝑧  ∈  On  ∧  ( 𝐵  ·o  𝑦 )  ∈  On  ∧  𝐴  ∈  On )  →  ( 𝑧  ∈  ( 𝐵  ·o  𝑦 )  →  𝑧  ⊆  ( 𝐵  ·o  𝑦 ) ) ) | 
						
							| 83 |  | omwordi | ⊢ ( ( 𝑧  ∈  On  ∧  ( 𝐵  ·o  𝑦 )  ∈  On  ∧  𝐴  ∈  On )  →  ( 𝑧  ⊆  ( 𝐵  ·o  𝑦 )  →  ( 𝐴  ·o  𝑧 )  ⊆  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) ) ) ) | 
						
							| 84 | 82 83 | syld | ⊢ ( ( 𝑧  ∈  On  ∧  ( 𝐵  ·o  𝑦 )  ∈  On  ∧  𝐴  ∈  On )  →  ( 𝑧  ∈  ( 𝐵  ·o  𝑦 )  →  ( 𝐴  ·o  𝑧 )  ⊆  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) ) ) ) | 
						
							| 85 | 84 | 3exp | ⊢ ( 𝑧  ∈  On  →  ( ( 𝐵  ·o  𝑦 )  ∈  On  →  ( 𝐴  ∈  On  →  ( 𝑧  ∈  ( 𝐵  ·o  𝑦 )  →  ( 𝐴  ·o  𝑧 )  ⊆  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) ) ) ) ) ) | 
						
							| 86 | 80 85 | syl5 | ⊢ ( 𝑧  ∈  On  →  ( ( 𝐵  ∈  On  ∧  ( Lim  𝑥  ∧  𝑦  ∈  𝑥 ) )  →  ( 𝐴  ∈  On  →  ( 𝑧  ∈  ( 𝐵  ·o  𝑦 )  →  ( 𝐴  ·o  𝑧 )  ⊆  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) ) ) ) ) ) | 
						
							| 87 | 86 | exp4d | ⊢ ( 𝑧  ∈  On  →  ( 𝐵  ∈  On  →  ( Lim  𝑥  →  ( 𝑦  ∈  𝑥  →  ( 𝐴  ∈  On  →  ( 𝑧  ∈  ( 𝐵  ·o  𝑦 )  →  ( 𝐴  ·o  𝑧 )  ⊆  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) ) ) ) ) ) ) ) | 
						
							| 88 | 87 | imp32 | ⊢ ( ( 𝑧  ∈  On  ∧  ( 𝐵  ∈  On  ∧  Lim  𝑥 ) )  →  ( 𝑦  ∈  𝑥  →  ( 𝐴  ∈  On  →  ( 𝑧  ∈  ( 𝐵  ·o  𝑦 )  →  ( 𝐴  ·o  𝑧 )  ⊆  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) ) ) ) ) ) | 
						
							| 89 | 88 | com23 | ⊢ ( ( 𝑧  ∈  On  ∧  ( 𝐵  ∈  On  ∧  Lim  𝑥 ) )  →  ( 𝐴  ∈  On  →  ( 𝑦  ∈  𝑥  →  ( 𝑧  ∈  ( 𝐵  ·o  𝑦 )  →  ( 𝐴  ·o  𝑧 )  ⊆  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) ) ) ) ) ) | 
						
							| 90 | 89 | imp | ⊢ ( ( ( 𝑧  ∈  On  ∧  ( 𝐵  ∈  On  ∧  Lim  𝑥 ) )  ∧  𝐴  ∈  On )  →  ( 𝑦  ∈  𝑥  →  ( 𝑧  ∈  ( 𝐵  ·o  𝑦 )  →  ( 𝐴  ·o  𝑧 )  ⊆  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) ) ) ) ) | 
						
							| 91 | 90 | reximdvai | ⊢ ( ( ( 𝑧  ∈  On  ∧  ( 𝐵  ∈  On  ∧  Lim  𝑥 ) )  ∧  𝐴  ∈  On )  →  ( ∃ 𝑦  ∈  𝑥 𝑧  ∈  ( 𝐵  ·o  𝑦 )  →  ∃ 𝑦  ∈  𝑥 ( 𝐴  ·o  𝑧 )  ⊆  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) ) ) ) | 
						
							| 92 | 77 91 | syld | ⊢ ( ( ( 𝑧  ∈  On  ∧  ( 𝐵  ∈  On  ∧  Lim  𝑥 ) )  ∧  𝐴  ∈  On )  →  ( 𝑧  ∈  ( 𝐵  ·o  𝑥 )  →  ∃ 𝑦  ∈  𝑥 ( 𝐴  ·o  𝑧 )  ⊆  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) ) ) ) | 
						
							| 93 | 92 | exp31 | ⊢ ( 𝑧  ∈  On  →  ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  →  ( 𝐴  ∈  On  →  ( 𝑧  ∈  ( 𝐵  ·o  𝑥 )  →  ∃ 𝑦  ∈  𝑥 ( 𝐴  ·o  𝑧 )  ⊆  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) ) ) ) ) ) | 
						
							| 94 | 93 | imp4c | ⊢ ( 𝑧  ∈  On  →  ( ( ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  ∧  𝐴  ∈  On )  ∧  𝑧  ∈  ( 𝐵  ·o  𝑥 ) )  →  ∃ 𝑦  ∈  𝑥 ( 𝐴  ·o  𝑧 )  ⊆  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) ) ) ) | 
						
							| 95 | 73 94 | mpcom | ⊢ ( ( ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  ∧  𝐴  ∈  On )  ∧  𝑧  ∈  ( 𝐵  ·o  𝑥 ) )  →  ∃ 𝑦  ∈  𝑥 ( 𝐴  ·o  𝑧 )  ⊆  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) ) ) | 
						
							| 96 | 95 | ralrimiva | ⊢ ( ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  ∧  𝐴  ∈  On )  →  ∀ 𝑧  ∈  ( 𝐵  ·o  𝑥 ) ∃ 𝑦  ∈  𝑥 ( 𝐴  ·o  𝑧 )  ⊆  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) ) ) | 
						
							| 97 |  | iunss2 | ⊢ ( ∀ 𝑧  ∈  ( 𝐵  ·o  𝑥 ) ∃ 𝑦  ∈  𝑥 ( 𝐴  ·o  𝑧 )  ⊆  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  →  ∪  𝑧  ∈  ( 𝐵  ·o  𝑥 ) ( 𝐴  ·o  𝑧 )  ⊆  ∪  𝑦  ∈  𝑥 ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) ) ) | 
						
							| 98 | 96 97 | syl | ⊢ ( ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  ∧  𝐴  ∈  On )  →  ∪  𝑧  ∈  ( 𝐵  ·o  𝑥 ) ( 𝐴  ·o  𝑧 )  ⊆  ∪  𝑦  ∈  𝑥 ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) ) ) | 
						
							| 99 | 98 | adantr | ⊢ ( ( ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  ∧  𝐴  ∈  On )  ∧  ∅  ∈  𝐵 )  →  ∪  𝑧  ∈  ( 𝐵  ·o  𝑥 ) ( 𝐴  ·o  𝑧 )  ⊆  ∪  𝑦  ∈  𝑥 ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) ) ) | 
						
							| 100 | 68 99 | eqssd | ⊢ ( ( ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  ∧  𝐴  ∈  On )  ∧  ∅  ∈  𝐵 )  →  ∪  𝑦  ∈  𝑥 ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  =  ∪  𝑧  ∈  ( 𝐵  ·o  𝑥 ) ( 𝐴  ·o  𝑧 ) ) | 
						
							| 101 |  | omlimcl | ⊢ ( ( ( 𝐵  ∈  On  ∧  ( 𝑥  ∈  V  ∧  Lim  𝑥 ) )  ∧  ∅  ∈  𝐵 )  →  Lim  ( 𝐵  ·o  𝑥 ) ) | 
						
							| 102 | 46 101 | mpanlr1 | ⊢ ( ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  ∧  ∅  ∈  𝐵 )  →  Lim  ( 𝐵  ·o  𝑥 ) ) | 
						
							| 103 |  | ovex | ⊢ ( 𝐵  ·o  𝑥 )  ∈  V | 
						
							| 104 |  | omlim | ⊢ ( ( 𝐴  ∈  On  ∧  ( ( 𝐵  ·o  𝑥 )  ∈  V  ∧  Lim  ( 𝐵  ·o  𝑥 ) ) )  →  ( 𝐴  ·o  ( 𝐵  ·o  𝑥 ) )  =  ∪  𝑧  ∈  ( 𝐵  ·o  𝑥 ) ( 𝐴  ·o  𝑧 ) ) | 
						
							| 105 | 103 104 | mpanr1 | ⊢ ( ( 𝐴  ∈  On  ∧  Lim  ( 𝐵  ·o  𝑥 ) )  →  ( 𝐴  ·o  ( 𝐵  ·o  𝑥 ) )  =  ∪  𝑧  ∈  ( 𝐵  ·o  𝑥 ) ( 𝐴  ·o  𝑧 ) ) | 
						
							| 106 | 102 105 | sylan2 | ⊢ ( ( 𝐴  ∈  On  ∧  ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  ∧  ∅  ∈  𝐵 ) )  →  ( 𝐴  ·o  ( 𝐵  ·o  𝑥 ) )  =  ∪  𝑧  ∈  ( 𝐵  ·o  𝑥 ) ( 𝐴  ·o  𝑧 ) ) | 
						
							| 107 | 106 | ancoms | ⊢ ( ( ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  ∧  ∅  ∈  𝐵 )  ∧  𝐴  ∈  On )  →  ( 𝐴  ·o  ( 𝐵  ·o  𝑥 ) )  =  ∪  𝑧  ∈  ( 𝐵  ·o  𝑥 ) ( 𝐴  ·o  𝑧 ) ) | 
						
							| 108 | 107 | an32s | ⊢ ( ( ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  ∧  𝐴  ∈  On )  ∧  ∅  ∈  𝐵 )  →  ( 𝐴  ·o  ( 𝐵  ·o  𝑥 ) )  =  ∪  𝑧  ∈  ( 𝐵  ·o  𝑥 ) ( 𝐴  ·o  𝑧 ) ) | 
						
							| 109 | 100 108 | eqtr4d | ⊢ ( ( ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  ∧  𝐴  ∈  On )  ∧  ∅  ∈  𝐵 )  →  ∪  𝑦  ∈  𝑥 ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑥 ) ) ) | 
						
							| 110 | 52 109 | sylan9eqr | ⊢ ( ( ( ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  ∧  𝐴  ∈  On )  ∧  ∅  ∈  𝐵 )  ∧  ∀ 𝑦  ∈  𝑥 ( ( 𝐴  ·o  𝐵 )  ·o  𝑦 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) ) )  →  ∪  𝑦  ∈  𝑥 ( ( 𝐴  ·o  𝐵 )  ·o  𝑦 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑥 ) ) ) | 
						
							| 111 | 51 110 | eqtrd | ⊢ ( ( ( ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  ∧  𝐴  ∈  On )  ∧  ∅  ∈  𝐵 )  ∧  ∀ 𝑦  ∈  𝑥 ( ( 𝐴  ·o  𝐵 )  ·o  𝑦 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) ) )  →  ( ( 𝐴  ·o  𝐵 )  ·o  𝑥 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑥 ) ) ) | 
						
							| 112 | 111 | exp31 | ⊢ ( ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  ∧  𝐴  ∈  On )  →  ( ∅  ∈  𝐵  →  ( ∀ 𝑦  ∈  𝑥 ( ( 𝐴  ·o  𝐵 )  ·o  𝑦 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  →  ( ( 𝐴  ·o  𝐵 )  ·o  𝑥 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑥 ) ) ) ) ) | 
						
							| 113 |  | eloni | ⊢ ( 𝐵  ∈  On  →  Ord  𝐵 ) | 
						
							| 114 |  | ord0eln0 | ⊢ ( Ord  𝐵  →  ( ∅  ∈  𝐵  ↔  𝐵  ≠  ∅ ) ) | 
						
							| 115 | 114 | necon2bbid | ⊢ ( Ord  𝐵  →  ( 𝐵  =  ∅  ↔  ¬  ∅  ∈  𝐵 ) ) | 
						
							| 116 | 113 115 | syl | ⊢ ( 𝐵  ∈  On  →  ( 𝐵  =  ∅  ↔  ¬  ∅  ∈  𝐵 ) ) | 
						
							| 117 | 116 | ad2antrr | ⊢ ( ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  ∧  𝐴  ∈  On )  →  ( 𝐵  =  ∅  ↔  ¬  ∅  ∈  𝐵 ) ) | 
						
							| 118 |  | oveq2 | ⊢ ( 𝐵  =  ∅  →  ( 𝐴  ·o  𝐵 )  =  ( 𝐴  ·o  ∅ ) ) | 
						
							| 119 | 118 22 | sylan9eqr | ⊢ ( ( 𝐴  ∈  On  ∧  𝐵  =  ∅ )  →  ( 𝐴  ·o  𝐵 )  =  ∅ ) | 
						
							| 120 | 119 | oveq1d | ⊢ ( ( 𝐴  ∈  On  ∧  𝐵  =  ∅ )  →  ( ( 𝐴  ·o  𝐵 )  ·o  𝑥 )  =  ( ∅  ·o  𝑥 ) ) | 
						
							| 121 |  | om0r | ⊢ ( 𝑥  ∈  On  →  ( ∅  ·o  𝑥 )  =  ∅ ) | 
						
							| 122 | 120 121 | sylan9eqr | ⊢ ( ( 𝑥  ∈  On  ∧  ( 𝐴  ∈  On  ∧  𝐵  =  ∅ ) )  →  ( ( 𝐴  ·o  𝐵 )  ·o  𝑥 )  =  ∅ ) | 
						
							| 123 | 122 | anassrs | ⊢ ( ( ( 𝑥  ∈  On  ∧  𝐴  ∈  On )  ∧  𝐵  =  ∅ )  →  ( ( 𝐴  ·o  𝐵 )  ·o  𝑥 )  =  ∅ ) | 
						
							| 124 |  | oveq1 | ⊢ ( 𝐵  =  ∅  →  ( 𝐵  ·o  𝑥 )  =  ( ∅  ·o  𝑥 ) ) | 
						
							| 125 | 124 121 | sylan9eqr | ⊢ ( ( 𝑥  ∈  On  ∧  𝐵  =  ∅ )  →  ( 𝐵  ·o  𝑥 )  =  ∅ ) | 
						
							| 126 | 125 | oveq2d | ⊢ ( ( 𝑥  ∈  On  ∧  𝐵  =  ∅ )  →  ( 𝐴  ·o  ( 𝐵  ·o  𝑥 ) )  =  ( 𝐴  ·o  ∅ ) ) | 
						
							| 127 | 126 22 | sylan9eq | ⊢ ( ( ( 𝑥  ∈  On  ∧  𝐵  =  ∅ )  ∧  𝐴  ∈  On )  →  ( 𝐴  ·o  ( 𝐵  ·o  𝑥 ) )  =  ∅ ) | 
						
							| 128 | 127 | an32s | ⊢ ( ( ( 𝑥  ∈  On  ∧  𝐴  ∈  On )  ∧  𝐵  =  ∅ )  →  ( 𝐴  ·o  ( 𝐵  ·o  𝑥 ) )  =  ∅ ) | 
						
							| 129 | 123 128 | eqtr4d | ⊢ ( ( ( 𝑥  ∈  On  ∧  𝐴  ∈  On )  ∧  𝐵  =  ∅ )  →  ( ( 𝐴  ·o  𝐵 )  ·o  𝑥 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑥 ) ) ) | 
						
							| 130 | 129 | ex | ⊢ ( ( 𝑥  ∈  On  ∧  𝐴  ∈  On )  →  ( 𝐵  =  ∅  →  ( ( 𝐴  ·o  𝐵 )  ·o  𝑥 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑥 ) ) ) ) | 
						
							| 131 | 54 130 | sylan | ⊢ ( ( Lim  𝑥  ∧  𝐴  ∈  On )  →  ( 𝐵  =  ∅  →  ( ( 𝐴  ·o  𝐵 )  ·o  𝑥 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑥 ) ) ) ) | 
						
							| 132 | 131 | adantll | ⊢ ( ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  ∧  𝐴  ∈  On )  →  ( 𝐵  =  ∅  →  ( ( 𝐴  ·o  𝐵 )  ·o  𝑥 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑥 ) ) ) ) | 
						
							| 133 | 117 132 | sylbird | ⊢ ( ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  ∧  𝐴  ∈  On )  →  ( ¬  ∅  ∈  𝐵  →  ( ( 𝐴  ·o  𝐵 )  ·o  𝑥 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑥 ) ) ) ) | 
						
							| 134 | 133 | a1dd | ⊢ ( ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  ∧  𝐴  ∈  On )  →  ( ¬  ∅  ∈  𝐵  →  ( ∀ 𝑦  ∈  𝑥 ( ( 𝐴  ·o  𝐵 )  ·o  𝑦 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  →  ( ( 𝐴  ·o  𝐵 )  ·o  𝑥 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑥 ) ) ) ) ) | 
						
							| 135 | 112 134 | pm2.61d | ⊢ ( ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  ∧  𝐴  ∈  On )  →  ( ∀ 𝑦  ∈  𝑥 ( ( 𝐴  ·o  𝐵 )  ·o  𝑦 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  →  ( ( 𝐴  ·o  𝐵 )  ·o  𝑥 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑥 ) ) ) ) | 
						
							| 136 | 135 | exp31 | ⊢ ( 𝐵  ∈  On  →  ( Lim  𝑥  →  ( 𝐴  ∈  On  →  ( ∀ 𝑦  ∈  𝑥 ( ( 𝐴  ·o  𝐵 )  ·o  𝑦 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  →  ( ( 𝐴  ·o  𝐵 )  ·o  𝑥 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑥 ) ) ) ) ) ) | 
						
							| 137 | 136 | com3l | ⊢ ( Lim  𝑥  →  ( 𝐴  ∈  On  →  ( 𝐵  ∈  On  →  ( ∀ 𝑦  ∈  𝑥 ( ( 𝐴  ·o  𝐵 )  ·o  𝑦 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  →  ( ( 𝐴  ·o  𝐵 )  ·o  𝑥 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑥 ) ) ) ) ) ) | 
						
							| 138 | 137 | impd | ⊢ ( Lim  𝑥  →  ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On )  →  ( ∀ 𝑦  ∈  𝑥 ( ( 𝐴  ·o  𝐵 )  ·o  𝑦 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑦 ) )  →  ( ( 𝐴  ·o  𝐵 )  ·o  𝑥 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝑥 ) ) ) ) ) | 
						
							| 139 | 4 8 12 16 24 44 138 | tfinds3 | ⊢ ( 𝐶  ∈  On  →  ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On )  →  ( ( 𝐴  ·o  𝐵 )  ·o  𝐶 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝐶 ) ) ) ) | 
						
							| 140 | 139 | expd | ⊢ ( 𝐶  ∈  On  →  ( 𝐴  ∈  On  →  ( 𝐵  ∈  On  →  ( ( 𝐴  ·o  𝐵 )  ·o  𝐶 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝐶 ) ) ) ) ) | 
						
							| 141 | 140 | com3l | ⊢ ( 𝐴  ∈  On  →  ( 𝐵  ∈  On  →  ( 𝐶  ∈  On  →  ( ( 𝐴  ·o  𝐵 )  ·o  𝐶 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝐶 ) ) ) ) ) | 
						
							| 142 | 141 | 3imp | ⊢ ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐶  ∈  On )  →  ( ( 𝐴  ·o  𝐵 )  ·o  𝐶 )  =  ( 𝐴  ·o  ( 𝐵  ·o  𝐶 ) ) ) |