| Step | Hyp | Ref | Expression | 
						
							| 1 |  | simp2 | ⊢ ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  →  𝐵  ∈  On ) | 
						
							| 2 |  | onsucb | ⊢ ( 𝐵  ∈  On  ↔  suc  𝐵  ∈  On ) | 
						
							| 3 | 1 2 | sylib | ⊢ ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  →  suc  𝐵  ∈  On ) | 
						
							| 4 |  | simp1 | ⊢ ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  →  𝐴  ∈  On ) | 
						
							| 5 |  | on0eln0 | ⊢ ( 𝐴  ∈  On  →  ( ∅  ∈  𝐴  ↔  𝐴  ≠  ∅ ) ) | 
						
							| 6 | 5 | biimpar | ⊢ ( ( 𝐴  ∈  On  ∧  𝐴  ≠  ∅ )  →  ∅  ∈  𝐴 ) | 
						
							| 7 | 6 | 3adant2 | ⊢ ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  →  ∅  ∈  𝐴 ) | 
						
							| 8 |  | omword2 | ⊢ ( ( ( suc  𝐵  ∈  On  ∧  𝐴  ∈  On )  ∧  ∅  ∈  𝐴 )  →  suc  𝐵  ⊆  ( 𝐴  ·o  suc  𝐵 ) ) | 
						
							| 9 | 3 4 7 8 | syl21anc | ⊢ ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  →  suc  𝐵  ⊆  ( 𝐴  ·o  suc  𝐵 ) ) | 
						
							| 10 |  | sucidg | ⊢ ( 𝐵  ∈  On  →  𝐵  ∈  suc  𝐵 ) | 
						
							| 11 |  | ssel | ⊢ ( suc  𝐵  ⊆  ( 𝐴  ·o  suc  𝐵 )  →  ( 𝐵  ∈  suc  𝐵  →  𝐵  ∈  ( 𝐴  ·o  suc  𝐵 ) ) ) | 
						
							| 12 | 10 11 | syl5 | ⊢ ( suc  𝐵  ⊆  ( 𝐴  ·o  suc  𝐵 )  →  ( 𝐵  ∈  On  →  𝐵  ∈  ( 𝐴  ·o  suc  𝐵 ) ) ) | 
						
							| 13 | 9 1 12 | sylc | ⊢ ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  →  𝐵  ∈  ( 𝐴  ·o  suc  𝐵 ) ) | 
						
							| 14 |  | suceq | ⊢ ( 𝑥  =  𝐵  →  suc  𝑥  =  suc  𝐵 ) | 
						
							| 15 | 14 | oveq2d | ⊢ ( 𝑥  =  𝐵  →  ( 𝐴  ·o  suc  𝑥 )  =  ( 𝐴  ·o  suc  𝐵 ) ) | 
						
							| 16 | 15 | eleq2d | ⊢ ( 𝑥  =  𝐵  →  ( 𝐵  ∈  ( 𝐴  ·o  suc  𝑥 )  ↔  𝐵  ∈  ( 𝐴  ·o  suc  𝐵 ) ) ) | 
						
							| 17 | 16 | rspcev | ⊢ ( ( 𝐵  ∈  On  ∧  𝐵  ∈  ( 𝐴  ·o  suc  𝐵 ) )  →  ∃ 𝑥  ∈  On 𝐵  ∈  ( 𝐴  ·o  suc  𝑥 ) ) | 
						
							| 18 | 1 13 17 | syl2anc | ⊢ ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  →  ∃ 𝑥  ∈  On 𝐵  ∈  ( 𝐴  ·o  suc  𝑥 ) ) | 
						
							| 19 |  | suceq | ⊢ ( 𝑥  =  𝑧  →  suc  𝑥  =  suc  𝑧 ) | 
						
							| 20 | 19 | oveq2d | ⊢ ( 𝑥  =  𝑧  →  ( 𝐴  ·o  suc  𝑥 )  =  ( 𝐴  ·o  suc  𝑧 ) ) | 
						
							| 21 | 20 | eleq2d | ⊢ ( 𝑥  =  𝑧  →  ( 𝐵  ∈  ( 𝐴  ·o  suc  𝑥 )  ↔  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 ) ) ) | 
						
							| 22 | 21 | onminex | ⊢ ( ∃ 𝑥  ∈  On 𝐵  ∈  ( 𝐴  ·o  suc  𝑥 )  →  ∃ 𝑥  ∈  On ( 𝐵  ∈  ( 𝐴  ·o  suc  𝑥 )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 ) ) ) | 
						
							| 23 |  | vex | ⊢ 𝑥  ∈  V | 
						
							| 24 | 23 | elon | ⊢ ( 𝑥  ∈  On  ↔  Ord  𝑥 ) | 
						
							| 25 |  | ordzsl | ⊢ ( Ord  𝑥  ↔  ( 𝑥  =  ∅  ∨  ∃ 𝑤  ∈  On 𝑥  =  suc  𝑤  ∨  Lim  𝑥 ) ) | 
						
							| 26 | 24 25 | bitri | ⊢ ( 𝑥  ∈  On  ↔  ( 𝑥  =  ∅  ∨  ∃ 𝑤  ∈  On 𝑥  =  suc  𝑤  ∨  Lim  𝑥 ) ) | 
						
							| 27 |  | oveq2 | ⊢ ( 𝑥  =  ∅  →  ( 𝐴  ·o  𝑥 )  =  ( 𝐴  ·o  ∅ ) ) | 
						
							| 28 |  | om0 | ⊢ ( 𝐴  ∈  On  →  ( 𝐴  ·o  ∅ )  =  ∅ ) | 
						
							| 29 | 27 28 | sylan9eqr | ⊢ ( ( 𝐴  ∈  On  ∧  𝑥  =  ∅ )  →  ( 𝐴  ·o  𝑥 )  =  ∅ ) | 
						
							| 30 |  | ne0i | ⊢ ( 𝐵  ∈  ( 𝐴  ·o  𝑥 )  →  ( 𝐴  ·o  𝑥 )  ≠  ∅ ) | 
						
							| 31 | 30 | necon2bi | ⊢ ( ( 𝐴  ·o  𝑥 )  =  ∅  →  ¬  𝐵  ∈  ( 𝐴  ·o  𝑥 ) ) | 
						
							| 32 | 29 31 | syl | ⊢ ( ( 𝐴  ∈  On  ∧  𝑥  =  ∅ )  →  ¬  𝐵  ∈  ( 𝐴  ·o  𝑥 ) ) | 
						
							| 33 | 32 | ex | ⊢ ( 𝐴  ∈  On  →  ( 𝑥  =  ∅  →  ¬  𝐵  ∈  ( 𝐴  ·o  𝑥 ) ) ) | 
						
							| 34 | 33 | a1d | ⊢ ( 𝐴  ∈  On  →  ( ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  →  ( 𝑥  =  ∅  →  ¬  𝐵  ∈  ( 𝐴  ·o  𝑥 ) ) ) ) | 
						
							| 35 | 34 | 3ad2ant1 | ⊢ ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  →  ( ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  →  ( 𝑥  =  ∅  →  ¬  𝐵  ∈  ( 𝐴  ·o  𝑥 ) ) ) ) | 
						
							| 36 | 35 | imp | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 ) )  →  ( 𝑥  =  ∅  →  ¬  𝐵  ∈  ( 𝐴  ·o  𝑥 ) ) ) | 
						
							| 37 |  | simp3 | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ∧  𝑥  =  suc  𝑤 )  →  𝑥  =  suc  𝑤 ) | 
						
							| 38 |  | simp2 | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ∧  𝑥  =  suc  𝑤 )  →  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 ) ) | 
						
							| 39 |  | raleq | ⊢ ( 𝑥  =  suc  𝑤  →  ( ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ↔  ∀ 𝑧  ∈  suc  𝑤 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 ) ) ) | 
						
							| 40 |  | vex | ⊢ 𝑤  ∈  V | 
						
							| 41 | 40 | sucid | ⊢ 𝑤  ∈  suc  𝑤 | 
						
							| 42 |  | suceq | ⊢ ( 𝑧  =  𝑤  →  suc  𝑧  =  suc  𝑤 ) | 
						
							| 43 | 42 | oveq2d | ⊢ ( 𝑧  =  𝑤  →  ( 𝐴  ·o  suc  𝑧 )  =  ( 𝐴  ·o  suc  𝑤 ) ) | 
						
							| 44 | 43 | eleq2d | ⊢ ( 𝑧  =  𝑤  →  ( 𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ↔  𝐵  ∈  ( 𝐴  ·o  suc  𝑤 ) ) ) | 
						
							| 45 | 44 | notbid | ⊢ ( 𝑧  =  𝑤  →  ( ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ↔  ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑤 ) ) ) | 
						
							| 46 | 45 | rspcv | ⊢ ( 𝑤  ∈  suc  𝑤  →  ( ∀ 𝑧  ∈  suc  𝑤 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  →  ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑤 ) ) ) | 
						
							| 47 | 41 46 | ax-mp | ⊢ ( ∀ 𝑧  ∈  suc  𝑤 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  →  ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑤 ) ) | 
						
							| 48 | 39 47 | biimtrdi | ⊢ ( 𝑥  =  suc  𝑤  →  ( ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  →  ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑤 ) ) ) | 
						
							| 49 | 37 38 48 | sylc | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ∧  𝑥  =  suc  𝑤 )  →  ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑤 ) ) | 
						
							| 50 |  | oveq2 | ⊢ ( 𝑥  =  suc  𝑤  →  ( 𝐴  ·o  𝑥 )  =  ( 𝐴  ·o  suc  𝑤 ) ) | 
						
							| 51 | 50 | eleq2d | ⊢ ( 𝑥  =  suc  𝑤  →  ( 𝐵  ∈  ( 𝐴  ·o  𝑥 )  ↔  𝐵  ∈  ( 𝐴  ·o  suc  𝑤 ) ) ) | 
						
							| 52 | 51 | notbid | ⊢ ( 𝑥  =  suc  𝑤  →  ( ¬  𝐵  ∈  ( 𝐴  ·o  𝑥 )  ↔  ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑤 ) ) ) | 
						
							| 53 | 52 | biimpar | ⊢ ( ( 𝑥  =  suc  𝑤  ∧  ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑤 ) )  →  ¬  𝐵  ∈  ( 𝐴  ·o  𝑥 ) ) | 
						
							| 54 | 37 49 53 | syl2anc | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ∧  𝑥  =  suc  𝑤 )  →  ¬  𝐵  ∈  ( 𝐴  ·o  𝑥 ) ) | 
						
							| 55 | 54 | 3expia | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 ) )  →  ( 𝑥  =  suc  𝑤  →  ¬  𝐵  ∈  ( 𝐴  ·o  𝑥 ) ) ) | 
						
							| 56 | 55 | rexlimdvw | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 ) )  →  ( ∃ 𝑤  ∈  On 𝑥  =  suc  𝑤  →  ¬  𝐵  ∈  ( 𝐴  ·o  𝑥 ) ) ) | 
						
							| 57 |  | ralnex | ⊢ ( ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ↔  ¬  ∃ 𝑧  ∈  𝑥 𝐵  ∈  ( 𝐴  ·o  suc  𝑧 ) ) | 
						
							| 58 |  | simpr | ⊢ ( ( Lim  𝑥  ∧  𝐴  ∈  On )  →  𝐴  ∈  On ) | 
						
							| 59 | 23 | a1i | ⊢ ( ( Lim  𝑥  ∧  𝐴  ∈  On )  →  𝑥  ∈  V ) | 
						
							| 60 |  | simpl | ⊢ ( ( Lim  𝑥  ∧  𝐴  ∈  On )  →  Lim  𝑥 ) | 
						
							| 61 |  | omlim | ⊢ ( ( 𝐴  ∈  On  ∧  ( 𝑥  ∈  V  ∧  Lim  𝑥 ) )  →  ( 𝐴  ·o  𝑥 )  =  ∪  𝑧  ∈  𝑥 ( 𝐴  ·o  𝑧 ) ) | 
						
							| 62 | 58 59 60 61 | syl12anc | ⊢ ( ( Lim  𝑥  ∧  𝐴  ∈  On )  →  ( 𝐴  ·o  𝑥 )  =  ∪  𝑧  ∈  𝑥 ( 𝐴  ·o  𝑧 ) ) | 
						
							| 63 | 62 | eleq2d | ⊢ ( ( Lim  𝑥  ∧  𝐴  ∈  On )  →  ( 𝐵  ∈  ( 𝐴  ·o  𝑥 )  ↔  𝐵  ∈  ∪  𝑧  ∈  𝑥 ( 𝐴  ·o  𝑧 ) ) ) | 
						
							| 64 |  | eliun | ⊢ ( 𝐵  ∈  ∪  𝑧  ∈  𝑥 ( 𝐴  ·o  𝑧 )  ↔  ∃ 𝑧  ∈  𝑥 𝐵  ∈  ( 𝐴  ·o  𝑧 ) ) | 
						
							| 65 |  | limord | ⊢ ( Lim  𝑥  →  Ord  𝑥 ) | 
						
							| 66 | 65 | 3ad2ant1 | ⊢ ( ( Lim  𝑥  ∧  𝐴  ∈  On  ∧  𝑧  ∈  𝑥 )  →  Ord  𝑥 ) | 
						
							| 67 | 66 24 | sylibr | ⊢ ( ( Lim  𝑥  ∧  𝐴  ∈  On  ∧  𝑧  ∈  𝑥 )  →  𝑥  ∈  On ) | 
						
							| 68 |  | simp3 | ⊢ ( ( Lim  𝑥  ∧  𝐴  ∈  On  ∧  𝑧  ∈  𝑥 )  →  𝑧  ∈  𝑥 ) | 
						
							| 69 |  | onelon | ⊢ ( ( 𝑥  ∈  On  ∧  𝑧  ∈  𝑥 )  →  𝑧  ∈  On ) | 
						
							| 70 | 67 68 69 | syl2anc | ⊢ ( ( Lim  𝑥  ∧  𝐴  ∈  On  ∧  𝑧  ∈  𝑥 )  →  𝑧  ∈  On ) | 
						
							| 71 |  | onsuc | ⊢ ( 𝑧  ∈  On  →  suc  𝑧  ∈  On ) | 
						
							| 72 | 70 71 | syl | ⊢ ( ( Lim  𝑥  ∧  𝐴  ∈  On  ∧  𝑧  ∈  𝑥 )  →  suc  𝑧  ∈  On ) | 
						
							| 73 |  | simp2 | ⊢ ( ( Lim  𝑥  ∧  𝐴  ∈  On  ∧  𝑧  ∈  𝑥 )  →  𝐴  ∈  On ) | 
						
							| 74 |  | sssucid | ⊢ 𝑧  ⊆  suc  𝑧 | 
						
							| 75 |  | omwordi | ⊢ ( ( 𝑧  ∈  On  ∧  suc  𝑧  ∈  On  ∧  𝐴  ∈  On )  →  ( 𝑧  ⊆  suc  𝑧  →  ( 𝐴  ·o  𝑧 )  ⊆  ( 𝐴  ·o  suc  𝑧 ) ) ) | 
						
							| 76 | 74 75 | mpi | ⊢ ( ( 𝑧  ∈  On  ∧  suc  𝑧  ∈  On  ∧  𝐴  ∈  On )  →  ( 𝐴  ·o  𝑧 )  ⊆  ( 𝐴  ·o  suc  𝑧 ) ) | 
						
							| 77 | 70 72 73 76 | syl3anc | ⊢ ( ( Lim  𝑥  ∧  𝐴  ∈  On  ∧  𝑧  ∈  𝑥 )  →  ( 𝐴  ·o  𝑧 )  ⊆  ( 𝐴  ·o  suc  𝑧 ) ) | 
						
							| 78 | 77 | sseld | ⊢ ( ( Lim  𝑥  ∧  𝐴  ∈  On  ∧  𝑧  ∈  𝑥 )  →  ( 𝐵  ∈  ( 𝐴  ·o  𝑧 )  →  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 ) ) ) | 
						
							| 79 | 78 | 3expia | ⊢ ( ( Lim  𝑥  ∧  𝐴  ∈  On )  →  ( 𝑧  ∈  𝑥  →  ( 𝐵  ∈  ( 𝐴  ·o  𝑧 )  →  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 ) ) ) ) | 
						
							| 80 | 79 | reximdvai | ⊢ ( ( Lim  𝑥  ∧  𝐴  ∈  On )  →  ( ∃ 𝑧  ∈  𝑥 𝐵  ∈  ( 𝐴  ·o  𝑧 )  →  ∃ 𝑧  ∈  𝑥 𝐵  ∈  ( 𝐴  ·o  suc  𝑧 ) ) ) | 
						
							| 81 | 64 80 | biimtrid | ⊢ ( ( Lim  𝑥  ∧  𝐴  ∈  On )  →  ( 𝐵  ∈  ∪  𝑧  ∈  𝑥 ( 𝐴  ·o  𝑧 )  →  ∃ 𝑧  ∈  𝑥 𝐵  ∈  ( 𝐴  ·o  suc  𝑧 ) ) ) | 
						
							| 82 | 63 81 | sylbid | ⊢ ( ( Lim  𝑥  ∧  𝐴  ∈  On )  →  ( 𝐵  ∈  ( 𝐴  ·o  𝑥 )  →  ∃ 𝑧  ∈  𝑥 𝐵  ∈  ( 𝐴  ·o  suc  𝑧 ) ) ) | 
						
							| 83 | 82 | con3d | ⊢ ( ( Lim  𝑥  ∧  𝐴  ∈  On )  →  ( ¬  ∃ 𝑧  ∈  𝑥 𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  →  ¬  𝐵  ∈  ( 𝐴  ·o  𝑥 ) ) ) | 
						
							| 84 | 57 83 | biimtrid | ⊢ ( ( Lim  𝑥  ∧  𝐴  ∈  On )  →  ( ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  →  ¬  𝐵  ∈  ( 𝐴  ·o  𝑥 ) ) ) | 
						
							| 85 | 84 | expimpd | ⊢ ( Lim  𝑥  →  ( ( 𝐴  ∈  On  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 ) )  →  ¬  𝐵  ∈  ( 𝐴  ·o  𝑥 ) ) ) | 
						
							| 86 | 85 | com12 | ⊢ ( ( 𝐴  ∈  On  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 ) )  →  ( Lim  𝑥  →  ¬  𝐵  ∈  ( 𝐴  ·o  𝑥 ) ) ) | 
						
							| 87 | 86 | 3ad2antl1 | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 ) )  →  ( Lim  𝑥  →  ¬  𝐵  ∈  ( 𝐴  ·o  𝑥 ) ) ) | 
						
							| 88 | 36 56 87 | 3jaod | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 ) )  →  ( ( 𝑥  =  ∅  ∨  ∃ 𝑤  ∈  On 𝑥  =  suc  𝑤  ∨  Lim  𝑥 )  →  ¬  𝐵  ∈  ( 𝐴  ·o  𝑥 ) ) ) | 
						
							| 89 | 26 88 | biimtrid | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 ) )  →  ( 𝑥  ∈  On  →  ¬  𝐵  ∈  ( 𝐴  ·o  𝑥 ) ) ) | 
						
							| 90 | 89 | impr | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ( ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ∧  𝑥  ∈  On ) )  →  ¬  𝐵  ∈  ( 𝐴  ·o  𝑥 ) ) | 
						
							| 91 |  | simpl1 | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ( ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ∧  𝑥  ∈  On ) )  →  𝐴  ∈  On ) | 
						
							| 92 |  | simprr | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ( ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ∧  𝑥  ∈  On ) )  →  𝑥  ∈  On ) | 
						
							| 93 |  | omcl | ⊢ ( ( 𝐴  ∈  On  ∧  𝑥  ∈  On )  →  ( 𝐴  ·o  𝑥 )  ∈  On ) | 
						
							| 94 | 91 92 93 | syl2anc | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ( ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ∧  𝑥  ∈  On ) )  →  ( 𝐴  ·o  𝑥 )  ∈  On ) | 
						
							| 95 |  | simpl2 | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ( ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ∧  𝑥  ∈  On ) )  →  𝐵  ∈  On ) | 
						
							| 96 |  | ontri1 | ⊢ ( ( ( 𝐴  ·o  𝑥 )  ∈  On  ∧  𝐵  ∈  On )  →  ( ( 𝐴  ·o  𝑥 )  ⊆  𝐵  ↔  ¬  𝐵  ∈  ( 𝐴  ·o  𝑥 ) ) ) | 
						
							| 97 | 94 95 96 | syl2anc | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ( ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ∧  𝑥  ∈  On ) )  →  ( ( 𝐴  ·o  𝑥 )  ⊆  𝐵  ↔  ¬  𝐵  ∈  ( 𝐴  ·o  𝑥 ) ) ) | 
						
							| 98 | 90 97 | mpbird | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ( ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ∧  𝑥  ∈  On ) )  →  ( 𝐴  ·o  𝑥 )  ⊆  𝐵 ) | 
						
							| 99 |  | oawordex | ⊢ ( ( ( 𝐴  ·o  𝑥 )  ∈  On  ∧  𝐵  ∈  On )  →  ( ( 𝐴  ·o  𝑥 )  ⊆  𝐵  ↔  ∃ 𝑦  ∈  On ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  =  𝐵 ) ) | 
						
							| 100 | 94 95 99 | syl2anc | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ( ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ∧  𝑥  ∈  On ) )  →  ( ( 𝐴  ·o  𝑥 )  ⊆  𝐵  ↔  ∃ 𝑦  ∈  On ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  =  𝐵 ) ) | 
						
							| 101 | 98 100 | mpbid | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ( ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ∧  𝑥  ∈  On ) )  →  ∃ 𝑦  ∈  On ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  =  𝐵 ) | 
						
							| 102 | 101 | 3adantr1 | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ( 𝐵  ∈  ( 𝐴  ·o  suc  𝑥 )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ∧  𝑥  ∈  On ) )  →  ∃ 𝑦  ∈  On ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  =  𝐵 ) | 
						
							| 103 |  | simp3r | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ( 𝐵  ∈  ( 𝐴  ·o  suc  𝑥 )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ∧  𝑥  ∈  On )  ∧  ( 𝑦  ∈  On  ∧  ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  =  𝐵 ) )  →  ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  =  𝐵 ) | 
						
							| 104 |  | simp21 | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ( 𝐵  ∈  ( 𝐴  ·o  suc  𝑥 )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ∧  𝑥  ∈  On )  ∧  ( 𝑦  ∈  On  ∧  ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  =  𝐵 ) )  →  𝐵  ∈  ( 𝐴  ·o  suc  𝑥 ) ) | 
						
							| 105 |  | simp11 | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ( 𝐵  ∈  ( 𝐴  ·o  suc  𝑥 )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ∧  𝑥  ∈  On )  ∧  ( 𝑦  ∈  On  ∧  ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  =  𝐵 ) )  →  𝐴  ∈  On ) | 
						
							| 106 |  | simp23 | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ( 𝐵  ∈  ( 𝐴  ·o  suc  𝑥 )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ∧  𝑥  ∈  On )  ∧  ( 𝑦  ∈  On  ∧  ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  =  𝐵 ) )  →  𝑥  ∈  On ) | 
						
							| 107 |  | omsuc | ⊢ ( ( 𝐴  ∈  On  ∧  𝑥  ∈  On )  →  ( 𝐴  ·o  suc  𝑥 )  =  ( ( 𝐴  ·o  𝑥 )  +o  𝐴 ) ) | 
						
							| 108 | 105 106 107 | syl2anc | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ( 𝐵  ∈  ( 𝐴  ·o  suc  𝑥 )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ∧  𝑥  ∈  On )  ∧  ( 𝑦  ∈  On  ∧  ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  =  𝐵 ) )  →  ( 𝐴  ·o  suc  𝑥 )  =  ( ( 𝐴  ·o  𝑥 )  +o  𝐴 ) ) | 
						
							| 109 | 104 108 | eleqtrd | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ( 𝐵  ∈  ( 𝐴  ·o  suc  𝑥 )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ∧  𝑥  ∈  On )  ∧  ( 𝑦  ∈  On  ∧  ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  =  𝐵 ) )  →  𝐵  ∈  ( ( 𝐴  ·o  𝑥 )  +o  𝐴 ) ) | 
						
							| 110 | 103 109 | eqeltrd | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ( 𝐵  ∈  ( 𝐴  ·o  suc  𝑥 )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ∧  𝑥  ∈  On )  ∧  ( 𝑦  ∈  On  ∧  ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  =  𝐵 ) )  →  ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  ∈  ( ( 𝐴  ·o  𝑥 )  +o  𝐴 ) ) | 
						
							| 111 |  | simp3l | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ( 𝐵  ∈  ( 𝐴  ·o  suc  𝑥 )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ∧  𝑥  ∈  On )  ∧  ( 𝑦  ∈  On  ∧  ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  =  𝐵 ) )  →  𝑦  ∈  On ) | 
						
							| 112 | 105 106 93 | syl2anc | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ( 𝐵  ∈  ( 𝐴  ·o  suc  𝑥 )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ∧  𝑥  ∈  On )  ∧  ( 𝑦  ∈  On  ∧  ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  =  𝐵 ) )  →  ( 𝐴  ·o  𝑥 )  ∈  On ) | 
						
							| 113 |  | oaord | ⊢ ( ( 𝑦  ∈  On  ∧  𝐴  ∈  On  ∧  ( 𝐴  ·o  𝑥 )  ∈  On )  →  ( 𝑦  ∈  𝐴  ↔  ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  ∈  ( ( 𝐴  ·o  𝑥 )  +o  𝐴 ) ) ) | 
						
							| 114 | 111 105 112 113 | syl3anc | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ( 𝐵  ∈  ( 𝐴  ·o  suc  𝑥 )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ∧  𝑥  ∈  On )  ∧  ( 𝑦  ∈  On  ∧  ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  =  𝐵 ) )  →  ( 𝑦  ∈  𝐴  ↔  ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  ∈  ( ( 𝐴  ·o  𝑥 )  +o  𝐴 ) ) ) | 
						
							| 115 | 110 114 | mpbird | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ( 𝐵  ∈  ( 𝐴  ·o  suc  𝑥 )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ∧  𝑥  ∈  On )  ∧  ( 𝑦  ∈  On  ∧  ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  =  𝐵 ) )  →  𝑦  ∈  𝐴 ) | 
						
							| 116 | 115 103 | jca | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ( 𝐵  ∈  ( 𝐴  ·o  suc  𝑥 )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ∧  𝑥  ∈  On )  ∧  ( 𝑦  ∈  On  ∧  ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  =  𝐵 ) )  →  ( 𝑦  ∈  𝐴  ∧  ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  =  𝐵 ) ) | 
						
							| 117 | 116 | 3expia | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ( 𝐵  ∈  ( 𝐴  ·o  suc  𝑥 )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ∧  𝑥  ∈  On ) )  →  ( ( 𝑦  ∈  On  ∧  ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  =  𝐵 )  →  ( 𝑦  ∈  𝐴  ∧  ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  =  𝐵 ) ) ) | 
						
							| 118 | 117 | reximdv2 | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ( 𝐵  ∈  ( 𝐴  ·o  suc  𝑥 )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ∧  𝑥  ∈  On ) )  →  ( ∃ 𝑦  ∈  On ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  =  𝐵  →  ∃ 𝑦  ∈  𝐴 ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  =  𝐵 ) ) | 
						
							| 119 | 102 118 | mpd | ⊢ ( ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  ∧  ( 𝐵  ∈  ( 𝐴  ·o  suc  𝑥 )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ∧  𝑥  ∈  On ) )  →  ∃ 𝑦  ∈  𝐴 ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  =  𝐵 ) | 
						
							| 120 | 119 | expcom | ⊢ ( ( 𝐵  ∈  ( 𝐴  ·o  suc  𝑥 )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 )  ∧  𝑥  ∈  On )  →  ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  →  ∃ 𝑦  ∈  𝐴 ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  =  𝐵 ) ) | 
						
							| 121 | 120 | 3expia | ⊢ ( ( 𝐵  ∈  ( 𝐴  ·o  suc  𝑥 )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 ) )  →  ( 𝑥  ∈  On  →  ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  →  ∃ 𝑦  ∈  𝐴 ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  =  𝐵 ) ) ) | 
						
							| 122 | 121 | com13 | ⊢ ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  →  ( 𝑥  ∈  On  →  ( ( 𝐵  ∈  ( 𝐴  ·o  suc  𝑥 )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 ) )  →  ∃ 𝑦  ∈  𝐴 ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  =  𝐵 ) ) ) | 
						
							| 123 | 122 | reximdvai | ⊢ ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  →  ( ∃ 𝑥  ∈  On ( 𝐵  ∈  ( 𝐴  ·o  suc  𝑥 )  ∧  ∀ 𝑧  ∈  𝑥 ¬  𝐵  ∈  ( 𝐴  ·o  suc  𝑧 ) )  →  ∃ 𝑥  ∈  On ∃ 𝑦  ∈  𝐴 ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  =  𝐵 ) ) | 
						
							| 124 | 22 123 | syl5 | ⊢ ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  →  ( ∃ 𝑥  ∈  On 𝐵  ∈  ( 𝐴  ·o  suc  𝑥 )  →  ∃ 𝑥  ∈  On ∃ 𝑦  ∈  𝐴 ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  =  𝐵 ) ) | 
						
							| 125 | 18 124 | mpd | ⊢ ( ( 𝐴  ∈  On  ∧  𝐵  ∈  On  ∧  𝐴  ≠  ∅ )  →  ∃ 𝑥  ∈  On ∃ 𝑦  ∈  𝐴 ( ( 𝐴  ·o  𝑥 )  +o  𝑦 )  =  𝐵 ) |