| Step | Hyp | Ref | Expression | 
						
							| 1 |  | eleq2 | ⊢ ( 𝑥  =  ∅  →  ( 𝐵  ∈  𝑥  ↔  𝐵  ∈  ∅ ) ) | 
						
							| 2 |  | fveq2 | ⊢ ( 𝑥  =  ∅  →  ( 𝑅1 ‘ 𝑥 )  =  ( 𝑅1 ‘ ∅ ) ) | 
						
							| 3 | 2 | breq2d | ⊢ ( 𝑥  =  ∅  →  ( ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑥 )  ↔  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ ∅ ) ) ) | 
						
							| 4 | 1 3 | imbi12d | ⊢ ( 𝑥  =  ∅  →  ( ( 𝐵  ∈  𝑥  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑥 ) )  ↔  ( 𝐵  ∈  ∅  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ ∅ ) ) ) ) | 
						
							| 5 |  | eleq2 | ⊢ ( 𝑥  =  𝑦  →  ( 𝐵  ∈  𝑥  ↔  𝐵  ∈  𝑦 ) ) | 
						
							| 6 |  | fveq2 | ⊢ ( 𝑥  =  𝑦  →  ( 𝑅1 ‘ 𝑥 )  =  ( 𝑅1 ‘ 𝑦 ) ) | 
						
							| 7 | 6 | breq2d | ⊢ ( 𝑥  =  𝑦  →  ( ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑥 )  ↔  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑦 ) ) ) | 
						
							| 8 | 5 7 | imbi12d | ⊢ ( 𝑥  =  𝑦  →  ( ( 𝐵  ∈  𝑥  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑥 ) )  ↔  ( 𝐵  ∈  𝑦  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑦 ) ) ) ) | 
						
							| 9 |  | eleq2 | ⊢ ( 𝑥  =  suc  𝑦  →  ( 𝐵  ∈  𝑥  ↔  𝐵  ∈  suc  𝑦 ) ) | 
						
							| 10 |  | fveq2 | ⊢ ( 𝑥  =  suc  𝑦  →  ( 𝑅1 ‘ 𝑥 )  =  ( 𝑅1 ‘ suc  𝑦 ) ) | 
						
							| 11 | 10 | breq2d | ⊢ ( 𝑥  =  suc  𝑦  →  ( ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑥 )  ↔  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ suc  𝑦 ) ) ) | 
						
							| 12 | 9 11 | imbi12d | ⊢ ( 𝑥  =  suc  𝑦  →  ( ( 𝐵  ∈  𝑥  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑥 ) )  ↔  ( 𝐵  ∈  suc  𝑦  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ suc  𝑦 ) ) ) ) | 
						
							| 13 |  | eleq2 | ⊢ ( 𝑥  =  𝐴  →  ( 𝐵  ∈  𝑥  ↔  𝐵  ∈  𝐴 ) ) | 
						
							| 14 |  | fveq2 | ⊢ ( 𝑥  =  𝐴  →  ( 𝑅1 ‘ 𝑥 )  =  ( 𝑅1 ‘ 𝐴 ) ) | 
						
							| 15 | 14 | breq2d | ⊢ ( 𝑥  =  𝐴  →  ( ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑥 )  ↔  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝐴 ) ) ) | 
						
							| 16 | 13 15 | imbi12d | ⊢ ( 𝑥  =  𝐴  →  ( ( 𝐵  ∈  𝑥  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑥 ) )  ↔  ( 𝐵  ∈  𝐴  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝐴 ) ) ) ) | 
						
							| 17 |  | noel | ⊢ ¬  𝐵  ∈  ∅ | 
						
							| 18 | 17 | pm2.21i | ⊢ ( 𝐵  ∈  ∅  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ ∅ ) ) | 
						
							| 19 |  | elsuci | ⊢ ( 𝐵  ∈  suc  𝑦  →  ( 𝐵  ∈  𝑦  ∨  𝐵  =  𝑦 ) ) | 
						
							| 20 |  | sdomtr | ⊢ ( ( ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑦 )  ∧  ( 𝑅1 ‘ 𝑦 )  ≺  ( 𝑅1 ‘ suc  𝑦 ) )  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ suc  𝑦 ) ) | 
						
							| 21 | 20 | expcom | ⊢ ( ( 𝑅1 ‘ 𝑦 )  ≺  ( 𝑅1 ‘ suc  𝑦 )  →  ( ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑦 )  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ suc  𝑦 ) ) ) | 
						
							| 22 |  | fvex | ⊢ ( 𝑅1 ‘ 𝑦 )  ∈  V | 
						
							| 23 | 22 | canth2 | ⊢ ( 𝑅1 ‘ 𝑦 )  ≺  𝒫  ( 𝑅1 ‘ 𝑦 ) | 
						
							| 24 |  | r1suc | ⊢ ( 𝑦  ∈  On  →  ( 𝑅1 ‘ suc  𝑦 )  =  𝒫  ( 𝑅1 ‘ 𝑦 ) ) | 
						
							| 25 | 23 24 | breqtrrid | ⊢ ( 𝑦  ∈  On  →  ( 𝑅1 ‘ 𝑦 )  ≺  ( 𝑅1 ‘ suc  𝑦 ) ) | 
						
							| 26 | 21 25 | syl11 | ⊢ ( ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑦 )  →  ( 𝑦  ∈  On  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ suc  𝑦 ) ) ) | 
						
							| 27 | 26 | imim2i | ⊢ ( ( 𝐵  ∈  𝑦  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑦 ) )  →  ( 𝐵  ∈  𝑦  →  ( 𝑦  ∈  On  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ suc  𝑦 ) ) ) ) | 
						
							| 28 |  | fveq2 | ⊢ ( 𝐵  =  𝑦  →  ( 𝑅1 ‘ 𝐵 )  =  ( 𝑅1 ‘ 𝑦 ) ) | 
						
							| 29 | 28 | breq1d | ⊢ ( 𝐵  =  𝑦  →  ( ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ suc  𝑦 )  ↔  ( 𝑅1 ‘ 𝑦 )  ≺  ( 𝑅1 ‘ suc  𝑦 ) ) ) | 
						
							| 30 | 25 29 | imbitrrid | ⊢ ( 𝐵  =  𝑦  →  ( 𝑦  ∈  On  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ suc  𝑦 ) ) ) | 
						
							| 31 | 30 | a1i | ⊢ ( ( 𝐵  ∈  𝑦  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑦 ) )  →  ( 𝐵  =  𝑦  →  ( 𝑦  ∈  On  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ suc  𝑦 ) ) ) ) | 
						
							| 32 | 27 31 | jaod | ⊢ ( ( 𝐵  ∈  𝑦  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑦 ) )  →  ( ( 𝐵  ∈  𝑦  ∨  𝐵  =  𝑦 )  →  ( 𝑦  ∈  On  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ suc  𝑦 ) ) ) ) | 
						
							| 33 | 19 32 | syl5 | ⊢ ( ( 𝐵  ∈  𝑦  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑦 ) )  →  ( 𝐵  ∈  suc  𝑦  →  ( 𝑦  ∈  On  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ suc  𝑦 ) ) ) ) | 
						
							| 34 | 33 | com3r | ⊢ ( 𝑦  ∈  On  →  ( ( 𝐵  ∈  𝑦  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑦 ) )  →  ( 𝐵  ∈  suc  𝑦  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ suc  𝑦 ) ) ) ) | 
						
							| 35 |  | limuni | ⊢ ( Lim  𝑥  →  𝑥  =  ∪  𝑥 ) | 
						
							| 36 | 35 | eleq2d | ⊢ ( Lim  𝑥  →  ( 𝐵  ∈  𝑥  ↔  𝐵  ∈  ∪  𝑥 ) ) | 
						
							| 37 |  | eluni2 | ⊢ ( 𝐵  ∈  ∪  𝑥  ↔  ∃ 𝑦  ∈  𝑥 𝐵  ∈  𝑦 ) | 
						
							| 38 | 36 37 | bitrdi | ⊢ ( Lim  𝑥  →  ( 𝐵  ∈  𝑥  ↔  ∃ 𝑦  ∈  𝑥 𝐵  ∈  𝑦 ) ) | 
						
							| 39 |  | r19.29 | ⊢ ( ( ∀ 𝑦  ∈  𝑥 ( 𝐵  ∈  𝑦  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑦 ) )  ∧  ∃ 𝑦  ∈  𝑥 𝐵  ∈  𝑦 )  →  ∃ 𝑦  ∈  𝑥 ( ( 𝐵  ∈  𝑦  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑦 ) )  ∧  𝐵  ∈  𝑦 ) ) | 
						
							| 40 |  | fvex | ⊢ ( 𝑅1 ‘ 𝑥 )  ∈  V | 
						
							| 41 |  | ssiun2 | ⊢ ( 𝑦  ∈  𝑥  →  ( 𝑅1 ‘ 𝑦 )  ⊆  ∪  𝑦  ∈  𝑥 ( 𝑅1 ‘ 𝑦 ) ) | 
						
							| 42 |  | vex | ⊢ 𝑥  ∈  V | 
						
							| 43 |  | r1lim | ⊢ ( ( 𝑥  ∈  V  ∧  Lim  𝑥 )  →  ( 𝑅1 ‘ 𝑥 )  =  ∪  𝑦  ∈  𝑥 ( 𝑅1 ‘ 𝑦 ) ) | 
						
							| 44 | 42 43 | mpan | ⊢ ( Lim  𝑥  →  ( 𝑅1 ‘ 𝑥 )  =  ∪  𝑦  ∈  𝑥 ( 𝑅1 ‘ 𝑦 ) ) | 
						
							| 45 | 44 | sseq2d | ⊢ ( Lim  𝑥  →  ( ( 𝑅1 ‘ 𝑦 )  ⊆  ( 𝑅1 ‘ 𝑥 )  ↔  ( 𝑅1 ‘ 𝑦 )  ⊆  ∪  𝑦  ∈  𝑥 ( 𝑅1 ‘ 𝑦 ) ) ) | 
						
							| 46 | 41 45 | imbitrrid | ⊢ ( Lim  𝑥  →  ( 𝑦  ∈  𝑥  →  ( 𝑅1 ‘ 𝑦 )  ⊆  ( 𝑅1 ‘ 𝑥 ) ) ) | 
						
							| 47 |  | ssdomg | ⊢ ( ( 𝑅1 ‘ 𝑥 )  ∈  V  →  ( ( 𝑅1 ‘ 𝑦 )  ⊆  ( 𝑅1 ‘ 𝑥 )  →  ( 𝑅1 ‘ 𝑦 )  ≼  ( 𝑅1 ‘ 𝑥 ) ) ) | 
						
							| 48 | 40 46 47 | mpsylsyld | ⊢ ( Lim  𝑥  →  ( 𝑦  ∈  𝑥  →  ( 𝑅1 ‘ 𝑦 )  ≼  ( 𝑅1 ‘ 𝑥 ) ) ) | 
						
							| 49 |  | id | ⊢ ( ( 𝐵  ∈  𝑦  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑦 ) )  →  ( 𝐵  ∈  𝑦  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑦 ) ) ) | 
						
							| 50 | 49 | imp | ⊢ ( ( ( 𝐵  ∈  𝑦  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑦 ) )  ∧  𝐵  ∈  𝑦 )  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑦 ) ) | 
						
							| 51 |  | sdomdomtr | ⊢ ( ( ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑦 )  ∧  ( 𝑅1 ‘ 𝑦 )  ≼  ( 𝑅1 ‘ 𝑥 ) )  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑥 ) ) | 
						
							| 52 | 51 | expcom | ⊢ ( ( 𝑅1 ‘ 𝑦 )  ≼  ( 𝑅1 ‘ 𝑥 )  →  ( ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑦 )  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑥 ) ) ) | 
						
							| 53 | 50 52 | syl5 | ⊢ ( ( 𝑅1 ‘ 𝑦 )  ≼  ( 𝑅1 ‘ 𝑥 )  →  ( ( ( 𝐵  ∈  𝑦  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑦 ) )  ∧  𝐵  ∈  𝑦 )  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑥 ) ) ) | 
						
							| 54 | 48 53 | syl6 | ⊢ ( Lim  𝑥  →  ( 𝑦  ∈  𝑥  →  ( ( ( 𝐵  ∈  𝑦  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑦 ) )  ∧  𝐵  ∈  𝑦 )  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑥 ) ) ) ) | 
						
							| 55 | 54 | rexlimdv | ⊢ ( Lim  𝑥  →  ( ∃ 𝑦  ∈  𝑥 ( ( 𝐵  ∈  𝑦  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑦 ) )  ∧  𝐵  ∈  𝑦 )  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑥 ) ) ) | 
						
							| 56 | 39 55 | syl5 | ⊢ ( Lim  𝑥  →  ( ( ∀ 𝑦  ∈  𝑥 ( 𝐵  ∈  𝑦  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑦 ) )  ∧  ∃ 𝑦  ∈  𝑥 𝐵  ∈  𝑦 )  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑥 ) ) ) | 
						
							| 57 | 56 | expcomd | ⊢ ( Lim  𝑥  →  ( ∃ 𝑦  ∈  𝑥 𝐵  ∈  𝑦  →  ( ∀ 𝑦  ∈  𝑥 ( 𝐵  ∈  𝑦  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑦 ) )  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑥 ) ) ) ) | 
						
							| 58 | 38 57 | sylbid | ⊢ ( Lim  𝑥  →  ( 𝐵  ∈  𝑥  →  ( ∀ 𝑦  ∈  𝑥 ( 𝐵  ∈  𝑦  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑦 ) )  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑥 ) ) ) ) | 
						
							| 59 | 58 | com23 | ⊢ ( Lim  𝑥  →  ( ∀ 𝑦  ∈  𝑥 ( 𝐵  ∈  𝑦  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑦 ) )  →  ( 𝐵  ∈  𝑥  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝑥 ) ) ) ) | 
						
							| 60 | 4 8 12 16 18 34 59 | tfinds | ⊢ ( 𝐴  ∈  On  →  ( 𝐵  ∈  𝐴  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝐴 ) ) ) | 
						
							| 61 | 60 | imp | ⊢ ( ( 𝐴  ∈  On  ∧  𝐵  ∈  𝐴 )  →  ( 𝑅1 ‘ 𝐵 )  ≺  ( 𝑅1 ‘ 𝐴 ) ) |