| Step | Hyp | Ref | Expression | 
						
							| 1 |  | r1funlim | ⊢ ( Fun  𝑅1  ∧  Lim  dom  𝑅1 ) | 
						
							| 2 | 1 | simpri | ⊢ Lim  dom  𝑅1 | 
						
							| 3 |  | limsuc | ⊢ ( Lim  dom  𝑅1  →  ( 𝐵  ∈  dom  𝑅1  ↔  suc  𝐵  ∈  dom  𝑅1 ) ) | 
						
							| 4 | 2 3 | ax-mp | ⊢ ( 𝐵  ∈  dom  𝑅1  ↔  suc  𝐵  ∈  dom  𝑅1 ) | 
						
							| 5 |  | rankr1ag | ⊢ ( ( 𝐴  ∈  ∪  ( 𝑅1  “  On )  ∧  suc  𝐵  ∈  dom  𝑅1 )  →  ( 𝐴  ∈  ( 𝑅1 ‘ suc  𝐵 )  ↔  ( rank ‘ 𝐴 )  ∈  suc  𝐵 ) ) | 
						
							| 6 | 4 5 | sylan2b | ⊢ ( ( 𝐴  ∈  ∪  ( 𝑅1  “  On )  ∧  𝐵  ∈  dom  𝑅1 )  →  ( 𝐴  ∈  ( 𝑅1 ‘ suc  𝐵 )  ↔  ( rank ‘ 𝐴 )  ∈  suc  𝐵 ) ) | 
						
							| 7 |  | r1sucg | ⊢ ( 𝐵  ∈  dom  𝑅1  →  ( 𝑅1 ‘ suc  𝐵 )  =  𝒫  ( 𝑅1 ‘ 𝐵 ) ) | 
						
							| 8 | 7 | adantl | ⊢ ( ( 𝐴  ∈  ∪  ( 𝑅1  “  On )  ∧  𝐵  ∈  dom  𝑅1 )  →  ( 𝑅1 ‘ suc  𝐵 )  =  𝒫  ( 𝑅1 ‘ 𝐵 ) ) | 
						
							| 9 | 8 | eleq2d | ⊢ ( ( 𝐴  ∈  ∪  ( 𝑅1  “  On )  ∧  𝐵  ∈  dom  𝑅1 )  →  ( 𝐴  ∈  ( 𝑅1 ‘ suc  𝐵 )  ↔  𝐴  ∈  𝒫  ( 𝑅1 ‘ 𝐵 ) ) ) | 
						
							| 10 |  | fvex | ⊢ ( 𝑅1 ‘ 𝐵 )  ∈  V | 
						
							| 11 | 10 | elpw2 | ⊢ ( 𝐴  ∈  𝒫  ( 𝑅1 ‘ 𝐵 )  ↔  𝐴  ⊆  ( 𝑅1 ‘ 𝐵 ) ) | 
						
							| 12 | 9 11 | bitr2di | ⊢ ( ( 𝐴  ∈  ∪  ( 𝑅1  “  On )  ∧  𝐵  ∈  dom  𝑅1 )  →  ( 𝐴  ⊆  ( 𝑅1 ‘ 𝐵 )  ↔  𝐴  ∈  ( 𝑅1 ‘ suc  𝐵 ) ) ) | 
						
							| 13 |  | rankon | ⊢ ( rank ‘ 𝐴 )  ∈  On | 
						
							| 14 |  | limord | ⊢ ( Lim  dom  𝑅1  →  Ord  dom  𝑅1 ) | 
						
							| 15 | 2 14 | ax-mp | ⊢ Ord  dom  𝑅1 | 
						
							| 16 |  | ordelon | ⊢ ( ( Ord  dom  𝑅1  ∧  𝐵  ∈  dom  𝑅1 )  →  𝐵  ∈  On ) | 
						
							| 17 | 15 16 | mpan | ⊢ ( 𝐵  ∈  dom  𝑅1  →  𝐵  ∈  On ) | 
						
							| 18 | 17 | adantl | ⊢ ( ( 𝐴  ∈  ∪  ( 𝑅1  “  On )  ∧  𝐵  ∈  dom  𝑅1 )  →  𝐵  ∈  On ) | 
						
							| 19 |  | onsssuc | ⊢ ( ( ( rank ‘ 𝐴 )  ∈  On  ∧  𝐵  ∈  On )  →  ( ( rank ‘ 𝐴 )  ⊆  𝐵  ↔  ( rank ‘ 𝐴 )  ∈  suc  𝐵 ) ) | 
						
							| 20 | 13 18 19 | sylancr | ⊢ ( ( 𝐴  ∈  ∪  ( 𝑅1  “  On )  ∧  𝐵  ∈  dom  𝑅1 )  →  ( ( rank ‘ 𝐴 )  ⊆  𝐵  ↔  ( rank ‘ 𝐴 )  ∈  suc  𝐵 ) ) | 
						
							| 21 | 6 12 20 | 3bitr4d | ⊢ ( ( 𝐴  ∈  ∪  ( 𝑅1  “  On )  ∧  𝐵  ∈  dom  𝑅1 )  →  ( 𝐴  ⊆  ( 𝑅1 ‘ 𝐵 )  ↔  ( rank ‘ 𝐴 )  ⊆  𝐵 ) ) |