| Step | Hyp | Ref | Expression | 
						
							| 1 |  | oeoelem.1 | ⊢ 𝐴  ∈  On | 
						
							| 2 |  | oeoelem.2 | ⊢ ∅  ∈  𝐴 | 
						
							| 3 |  | oveq2 | ⊢ ( 𝑥  =  ∅  →  ( ( 𝐴  ↑o  𝐵 )  ↑o  𝑥 )  =  ( ( 𝐴  ↑o  𝐵 )  ↑o  ∅ ) ) | 
						
							| 4 |  | oveq2 | ⊢ ( 𝑥  =  ∅  →  ( 𝐵  ·o  𝑥 )  =  ( 𝐵  ·o  ∅ ) ) | 
						
							| 5 | 4 | oveq2d | ⊢ ( 𝑥  =  ∅  →  ( 𝐴  ↑o  ( 𝐵  ·o  𝑥 ) )  =  ( 𝐴  ↑o  ( 𝐵  ·o  ∅ ) ) ) | 
						
							| 6 | 3 5 | eqeq12d | ⊢ ( 𝑥  =  ∅  →  ( ( ( 𝐴  ↑o  𝐵 )  ↑o  𝑥 )  =  ( 𝐴  ↑o  ( 𝐵  ·o  𝑥 ) )  ↔  ( ( 𝐴  ↑o  𝐵 )  ↑o  ∅ )  =  ( 𝐴  ↑o  ( 𝐵  ·o  ∅ ) ) ) ) | 
						
							| 7 |  | oveq2 | ⊢ ( 𝑥  =  𝑦  →  ( ( 𝐴  ↑o  𝐵 )  ↑o  𝑥 )  =  ( ( 𝐴  ↑o  𝐵 )  ↑o  𝑦 ) ) | 
						
							| 8 |  | oveq2 | ⊢ ( 𝑥  =  𝑦  →  ( 𝐵  ·o  𝑥 )  =  ( 𝐵  ·o  𝑦 ) ) | 
						
							| 9 | 8 | oveq2d | ⊢ ( 𝑥  =  𝑦  →  ( 𝐴  ↑o  ( 𝐵  ·o  𝑥 ) )  =  ( 𝐴  ↑o  ( 𝐵  ·o  𝑦 ) ) ) | 
						
							| 10 | 7 9 | eqeq12d | ⊢ ( 𝑥  =  𝑦  →  ( ( ( 𝐴  ↑o  𝐵 )  ↑o  𝑥 )  =  ( 𝐴  ↑o  ( 𝐵  ·o  𝑥 ) )  ↔  ( ( 𝐴  ↑o  𝐵 )  ↑o  𝑦 )  =  ( 𝐴  ↑o  ( 𝐵  ·o  𝑦 ) ) ) ) | 
						
							| 11 |  | oveq2 | ⊢ ( 𝑥  =  suc  𝑦  →  ( ( 𝐴  ↑o  𝐵 )  ↑o  𝑥 )  =  ( ( 𝐴  ↑o  𝐵 )  ↑o  suc  𝑦 ) ) | 
						
							| 12 |  | oveq2 | ⊢ ( 𝑥  =  suc  𝑦  →  ( 𝐵  ·o  𝑥 )  =  ( 𝐵  ·o  suc  𝑦 ) ) | 
						
							| 13 | 12 | oveq2d | ⊢ ( 𝑥  =  suc  𝑦  →  ( 𝐴  ↑o  ( 𝐵  ·o  𝑥 ) )  =  ( 𝐴  ↑o  ( 𝐵  ·o  suc  𝑦 ) ) ) | 
						
							| 14 | 11 13 | 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 ) ) ) ) | 
						
							| 15 |  | oveq2 | ⊢ ( 𝑥  =  𝐶  →  ( ( 𝐴  ↑o  𝐵 )  ↑o  𝑥 )  =  ( ( 𝐴  ↑o  𝐵 )  ↑o  𝐶 ) ) | 
						
							| 16 |  | oveq2 | ⊢ ( 𝑥  =  𝐶  →  ( 𝐵  ·o  𝑥 )  =  ( 𝐵  ·o  𝐶 ) ) | 
						
							| 17 | 16 | oveq2d | ⊢ ( 𝑥  =  𝐶  →  ( 𝐴  ↑o  ( 𝐵  ·o  𝑥 ) )  =  ( 𝐴  ↑o  ( 𝐵  ·o  𝐶 ) ) ) | 
						
							| 18 | 15 17 | eqeq12d | ⊢ ( 𝑥  =  𝐶  →  ( ( ( 𝐴  ↑o  𝐵 )  ↑o  𝑥 )  =  ( 𝐴  ↑o  ( 𝐵  ·o  𝑥 ) )  ↔  ( ( 𝐴  ↑o  𝐵 )  ↑o  𝐶 )  =  ( 𝐴  ↑o  ( 𝐵  ·o  𝐶 ) ) ) ) | 
						
							| 19 |  | oecl | ⊢ ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On )  →  ( 𝐴  ↑o  𝐵 )  ∈  On ) | 
						
							| 20 | 1 19 | mpan | ⊢ ( 𝐵  ∈  On  →  ( 𝐴  ↑o  𝐵 )  ∈  On ) | 
						
							| 21 |  | oe0 | ⊢ ( ( 𝐴  ↑o  𝐵 )  ∈  On  →  ( ( 𝐴  ↑o  𝐵 )  ↑o  ∅ )  =  1o ) | 
						
							| 22 | 20 21 | syl | ⊢ ( 𝐵  ∈  On  →  ( ( 𝐴  ↑o  𝐵 )  ↑o  ∅ )  =  1o ) | 
						
							| 23 |  | om0 | ⊢ ( 𝐵  ∈  On  →  ( 𝐵  ·o  ∅ )  =  ∅ ) | 
						
							| 24 | 23 | oveq2d | ⊢ ( 𝐵  ∈  On  →  ( 𝐴  ↑o  ( 𝐵  ·o  ∅ ) )  =  ( 𝐴  ↑o  ∅ ) ) | 
						
							| 25 |  | oe0 | ⊢ ( 𝐴  ∈  On  →  ( 𝐴  ↑o  ∅ )  =  1o ) | 
						
							| 26 | 1 25 | ax-mp | ⊢ ( 𝐴  ↑o  ∅ )  =  1o | 
						
							| 27 | 24 26 | eqtrdi | ⊢ ( 𝐵  ∈  On  →  ( 𝐴  ↑o  ( 𝐵  ·o  ∅ ) )  =  1o ) | 
						
							| 28 | 22 27 | eqtr4d | ⊢ ( 𝐵  ∈  On  →  ( ( 𝐴  ↑o  𝐵 )  ↑o  ∅ )  =  ( 𝐴  ↑o  ( 𝐵  ·o  ∅ ) ) ) | 
						
							| 29 |  | 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 ) ) ) | 
						
							| 30 |  | oesuc | ⊢ ( ( ( 𝐴  ↑o  𝐵 )  ∈  On  ∧  𝑦  ∈  On )  →  ( ( 𝐴  ↑o  𝐵 )  ↑o  suc  𝑦 )  =  ( ( ( 𝐴  ↑o  𝐵 )  ↑o  𝑦 )  ·o  ( 𝐴  ↑o  𝐵 ) ) ) | 
						
							| 31 | 20 30 | sylan | ⊢ ( ( 𝐵  ∈  On  ∧  𝑦  ∈  On )  →  ( ( 𝐴  ↑o  𝐵 )  ↑o  suc  𝑦 )  =  ( ( ( 𝐴  ↑o  𝐵 )  ↑o  𝑦 )  ·o  ( 𝐴  ↑o  𝐵 ) ) ) | 
						
							| 32 |  | omsuc | ⊢ ( ( 𝐵  ∈  On  ∧  𝑦  ∈  On )  →  ( 𝐵  ·o  suc  𝑦 )  =  ( ( 𝐵  ·o  𝑦 )  +o  𝐵 ) ) | 
						
							| 33 | 32 | oveq2d | ⊢ ( ( 𝐵  ∈  On  ∧  𝑦  ∈  On )  →  ( 𝐴  ↑o  ( 𝐵  ·o  suc  𝑦 ) )  =  ( 𝐴  ↑o  ( ( 𝐵  ·o  𝑦 )  +o  𝐵 ) ) ) | 
						
							| 34 |  | omcl | ⊢ ( ( 𝐵  ∈  On  ∧  𝑦  ∈  On )  →  ( 𝐵  ·o  𝑦 )  ∈  On ) | 
						
							| 35 |  | oeoa | ⊢ ( ( 𝐴  ∈  On  ∧  ( 𝐵  ·o  𝑦 )  ∈  On  ∧  𝐵  ∈  On )  →  ( 𝐴  ↑o  ( ( 𝐵  ·o  𝑦 )  +o  𝐵 ) )  =  ( ( 𝐴  ↑o  ( 𝐵  ·o  𝑦 ) )  ·o  ( 𝐴  ↑o  𝐵 ) ) ) | 
						
							| 36 | 1 35 | mp3an1 | ⊢ ( ( ( 𝐵  ·o  𝑦 )  ∈  On  ∧  𝐵  ∈  On )  →  ( 𝐴  ↑o  ( ( 𝐵  ·o  𝑦 )  +o  𝐵 ) )  =  ( ( 𝐴  ↑o  ( 𝐵  ·o  𝑦 ) )  ·o  ( 𝐴  ↑o  𝐵 ) ) ) | 
						
							| 37 | 34 36 | sylan | ⊢ ( ( ( 𝐵  ∈  On  ∧  𝑦  ∈  On )  ∧  𝐵  ∈  On )  →  ( 𝐴  ↑o  ( ( 𝐵  ·o  𝑦 )  +o  𝐵 ) )  =  ( ( 𝐴  ↑o  ( 𝐵  ·o  𝑦 ) )  ·o  ( 𝐴  ↑o  𝐵 ) ) ) | 
						
							| 38 | 37 | anabss1 | ⊢ ( ( 𝐵  ∈  On  ∧  𝑦  ∈  On )  →  ( 𝐴  ↑o  ( ( 𝐵  ·o  𝑦 )  +o  𝐵 ) )  =  ( ( 𝐴  ↑o  ( 𝐵  ·o  𝑦 ) )  ·o  ( 𝐴  ↑o  𝐵 ) ) ) | 
						
							| 39 | 33 38 | eqtrd | ⊢ ( ( 𝐵  ∈  On  ∧  𝑦  ∈  On )  →  ( 𝐴  ↑o  ( 𝐵  ·o  suc  𝑦 ) )  =  ( ( 𝐴  ↑o  ( 𝐵  ·o  𝑦 ) )  ·o  ( 𝐴  ↑o  𝐵 ) ) ) | 
						
							| 40 | 31 39 | eqeq12d | ⊢ ( ( 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 | 29 40 | imbitrrid | ⊢ ( ( 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 | expcom | ⊢ ( 𝑦  ∈  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 ) ) ) ) ) | 
						
							| 43 |  | 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 ) ) ) | 
						
							| 44 |  | vex | ⊢ 𝑥  ∈  V | 
						
							| 45 |  | oen0 | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On )  ∧  ∅  ∈  𝐴 )  →  ∅  ∈  ( 𝐴  ↑o  𝐵 ) ) | 
						
							| 46 | 2 45 | mpan2 | ⊢ ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On )  →  ∅  ∈  ( 𝐴  ↑o  𝐵 ) ) | 
						
							| 47 |  | oelim | ⊢ ( ( ( ( 𝐴  ↑o  𝐵 )  ∈  On  ∧  ( 𝑥  ∈  V  ∧  Lim  𝑥 ) )  ∧  ∅  ∈  ( 𝐴  ↑o  𝐵 ) )  →  ( ( 𝐴  ↑o  𝐵 )  ↑o  𝑥 )  =  ∪  𝑦  ∈  𝑥 ( ( 𝐴  ↑o  𝐵 )  ↑o  𝑦 ) ) | 
						
							| 48 | 19 47 | sylanl1 | ⊢ ( ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On )  ∧  ( 𝑥  ∈  V  ∧  Lim  𝑥 ) )  ∧  ∅  ∈  ( 𝐴  ↑o  𝐵 ) )  →  ( ( 𝐴  ↑o  𝐵 )  ↑o  𝑥 )  =  ∪  𝑦  ∈  𝑥 ( ( 𝐴  ↑o  𝐵 )  ↑o  𝑦 ) ) | 
						
							| 49 | 46 48 | mpidan | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On )  ∧  ( 𝑥  ∈  V  ∧  Lim  𝑥 ) )  →  ( ( 𝐴  ↑o  𝐵 )  ↑o  𝑥 )  =  ∪  𝑦  ∈  𝑥 ( ( 𝐴  ↑o  𝐵 )  ↑o  𝑦 ) ) | 
						
							| 50 | 1 49 | mpanl1 | ⊢ ( ( 𝐵  ∈  On  ∧  ( 𝑥  ∈  V  ∧  Lim  𝑥 ) )  →  ( ( 𝐴  ↑o  𝐵 )  ↑o  𝑥 )  =  ∪  𝑦  ∈  𝑥 ( ( 𝐴  ↑o  𝐵 )  ↑o  𝑦 ) ) | 
						
							| 51 | 44 50 | mpanr1 | ⊢ ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  →  ( ( 𝐴  ↑o  𝐵 )  ↑o  𝑥 )  =  ∪  𝑦  ∈  𝑥 ( ( 𝐴  ↑o  𝐵 )  ↑o  𝑦 ) ) | 
						
							| 52 |  | omlim | ⊢ ( ( 𝐵  ∈  On  ∧  ( 𝑥  ∈  V  ∧  Lim  𝑥 ) )  →  ( 𝐵  ·o  𝑥 )  =  ∪  𝑦  ∈  𝑥 ( 𝐵  ·o  𝑦 ) ) | 
						
							| 53 | 44 52 | mpanr1 | ⊢ ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  →  ( 𝐵  ·o  𝑥 )  =  ∪  𝑦  ∈  𝑥 ( 𝐵  ·o  𝑦 ) ) | 
						
							| 54 | 53 | oveq2d | ⊢ ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  →  ( 𝐴  ↑o  ( 𝐵  ·o  𝑥 ) )  =  ( 𝐴  ↑o  ∪  𝑦  ∈  𝑥 ( 𝐵  ·o  𝑦 ) ) ) | 
						
							| 55 |  | limord | ⊢ ( Lim  𝑥  →  Ord  𝑥 ) | 
						
							| 56 |  | ordelon | ⊢ ( ( Ord  𝑥  ∧  𝑦  ∈  𝑥 )  →  𝑦  ∈  On ) | 
						
							| 57 | 55 56 | sylan | ⊢ ( ( Lim  𝑥  ∧  𝑦  ∈  𝑥 )  →  𝑦  ∈  On ) | 
						
							| 58 | 57 34 | sylan2 | ⊢ ( ( 𝐵  ∈  On  ∧  ( Lim  𝑥  ∧  𝑦  ∈  𝑥 ) )  →  ( 𝐵  ·o  𝑦 )  ∈  On ) | 
						
							| 59 | 58 | anassrs | ⊢ ( ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  ∧  𝑦  ∈  𝑥 )  →  ( 𝐵  ·o  𝑦 )  ∈  On ) | 
						
							| 60 | 59 | ralrimiva | ⊢ ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  →  ∀ 𝑦  ∈  𝑥 ( 𝐵  ·o  𝑦 )  ∈  On ) | 
						
							| 61 |  | 0ellim | ⊢ ( Lim  𝑥  →  ∅  ∈  𝑥 ) | 
						
							| 62 | 61 | ne0d | ⊢ ( Lim  𝑥  →  𝑥  ≠  ∅ ) | 
						
							| 63 | 62 | adantl | ⊢ ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  →  𝑥  ≠  ∅ ) | 
						
							| 64 |  | vex | ⊢ 𝑤  ∈  V | 
						
							| 65 |  | oelim | ⊢ ( ( ( 𝐴  ∈  On  ∧  ( 𝑤  ∈  V  ∧  Lim  𝑤 ) )  ∧  ∅  ∈  𝐴 )  →  ( 𝐴  ↑o  𝑤 )  =  ∪  𝑧  ∈  𝑤 ( 𝐴  ↑o  𝑧 ) ) | 
						
							| 66 | 2 65 | mpan2 | ⊢ ( ( 𝐴  ∈  On  ∧  ( 𝑤  ∈  V  ∧  Lim  𝑤 ) )  →  ( 𝐴  ↑o  𝑤 )  =  ∪  𝑧  ∈  𝑤 ( 𝐴  ↑o  𝑧 ) ) | 
						
							| 67 | 1 66 | mpan | ⊢ ( ( 𝑤  ∈  V  ∧  Lim  𝑤 )  →  ( 𝐴  ↑o  𝑤 )  =  ∪  𝑧  ∈  𝑤 ( 𝐴  ↑o  𝑧 ) ) | 
						
							| 68 | 64 67 | mpan | ⊢ ( Lim  𝑤  →  ( 𝐴  ↑o  𝑤 )  =  ∪  𝑧  ∈  𝑤 ( 𝐴  ↑o  𝑧 ) ) | 
						
							| 69 |  | oewordi | ⊢ ( ( ( 𝑧  ∈  On  ∧  𝑤  ∈  On  ∧  𝐴  ∈  On )  ∧  ∅  ∈  𝐴 )  →  ( 𝑧  ⊆  𝑤  →  ( 𝐴  ↑o  𝑧 )  ⊆  ( 𝐴  ↑o  𝑤 ) ) ) | 
						
							| 70 | 2 69 | mpan2 | ⊢ ( ( 𝑧  ∈  On  ∧  𝑤  ∈  On  ∧  𝐴  ∈  On )  →  ( 𝑧  ⊆  𝑤  →  ( 𝐴  ↑o  𝑧 )  ⊆  ( 𝐴  ↑o  𝑤 ) ) ) | 
						
							| 71 | 1 70 | mp3an3 | ⊢ ( ( 𝑧  ∈  On  ∧  𝑤  ∈  On )  →  ( 𝑧  ⊆  𝑤  →  ( 𝐴  ↑o  𝑧 )  ⊆  ( 𝐴  ↑o  𝑤 ) ) ) | 
						
							| 72 | 71 | 3impia | ⊢ ( ( 𝑧  ∈  On  ∧  𝑤  ∈  On  ∧  𝑧  ⊆  𝑤 )  →  ( 𝐴  ↑o  𝑧 )  ⊆  ( 𝐴  ↑o  𝑤 ) ) | 
						
							| 73 | 68 72 | onoviun | ⊢ ( ( 𝑥  ∈  V  ∧  ∀ 𝑦  ∈  𝑥 ( 𝐵  ·o  𝑦 )  ∈  On  ∧  𝑥  ≠  ∅ )  →  ( 𝐴  ↑o  ∪  𝑦  ∈  𝑥 ( 𝐵  ·o  𝑦 ) )  =  ∪  𝑦  ∈  𝑥 ( 𝐴  ↑o  ( 𝐵  ·o  𝑦 ) ) ) | 
						
							| 74 | 44 60 63 73 | mp3an2i | ⊢ ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  →  ( 𝐴  ↑o  ∪  𝑦  ∈  𝑥 ( 𝐵  ·o  𝑦 ) )  =  ∪  𝑦  ∈  𝑥 ( 𝐴  ↑o  ( 𝐵  ·o  𝑦 ) ) ) | 
						
							| 75 | 54 74 | eqtrd | ⊢ ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  →  ( 𝐴  ↑o  ( 𝐵  ·o  𝑥 ) )  =  ∪  𝑦  ∈  𝑥 ( 𝐴  ↑o  ( 𝐵  ·o  𝑦 ) ) ) | 
						
							| 76 | 51 75 | eqeq12d | ⊢ ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  →  ( ( ( 𝐴  ↑o  𝐵 )  ↑o  𝑥 )  =  ( 𝐴  ↑o  ( 𝐵  ·o  𝑥 ) )  ↔  ∪  𝑦  ∈  𝑥 ( ( 𝐴  ↑o  𝐵 )  ↑o  𝑦 )  =  ∪  𝑦  ∈  𝑥 ( 𝐴  ↑o  ( 𝐵  ·o  𝑦 ) ) ) ) | 
						
							| 77 | 43 76 | imbitrrid | ⊢ ( ( 𝐵  ∈  On  ∧  Lim  𝑥 )  →  ( ∀ 𝑦  ∈  𝑥 ( ( 𝐴  ↑o  𝐵 )  ↑o  𝑦 )  =  ( 𝐴  ↑o  ( 𝐵  ·o  𝑦 ) )  →  ( ( 𝐴  ↑o  𝐵 )  ↑o  𝑥 )  =  ( 𝐴  ↑o  ( 𝐵  ·o  𝑥 ) ) ) ) | 
						
							| 78 | 77 | expcom | ⊢ ( Lim  𝑥  →  ( 𝐵  ∈  On  →  ( ∀ 𝑦  ∈  𝑥 ( ( 𝐴  ↑o  𝐵 )  ↑o  𝑦 )  =  ( 𝐴  ↑o  ( 𝐵  ·o  𝑦 ) )  →  ( ( 𝐴  ↑o  𝐵 )  ↑o  𝑥 )  =  ( 𝐴  ↑o  ( 𝐵  ·o  𝑥 ) ) ) ) ) | 
						
							| 79 | 6 10 14 18 28 42 78 | tfinds3 | ⊢ ( 𝐶  ∈  On  →  ( 𝐵  ∈  On  →  ( ( 𝐴  ↑o  𝐵 )  ↑o  𝐶 )  =  ( 𝐴  ↑o  ( 𝐵  ·o  𝐶 ) ) ) ) | 
						
							| 80 | 79 | impcom | ⊢ ( ( 𝐵  ∈  On  ∧  𝐶  ∈  On )  →  ( ( 𝐴  ↑o  𝐵 )  ↑o  𝐶 )  =  ( 𝐴  ↑o  ( 𝐵  ·o  𝐶 ) ) ) |