| Step | Hyp | Ref | Expression | 
						
							| 1 |  | fof | ⊢ ( 𝐹 : 𝐴 –onto→ 𝐵  →  𝐹 : 𝐴 ⟶ 𝐵 ) | 
						
							| 2 |  | smo11 | ⊢ ( ( 𝐹 : 𝐴 ⟶ 𝐵  ∧  Smo  𝐹 )  →  𝐹 : 𝐴 –1-1→ 𝐵 ) | 
						
							| 3 | 1 2 | sylan | ⊢ ( ( 𝐹 : 𝐴 –onto→ 𝐵  ∧  Smo  𝐹 )  →  𝐹 : 𝐴 –1-1→ 𝐵 ) | 
						
							| 4 |  | simpl | ⊢ ( ( 𝐹 : 𝐴 –onto→ 𝐵  ∧  Smo  𝐹 )  →  𝐹 : 𝐴 –onto→ 𝐵 ) | 
						
							| 5 |  | df-f1o | ⊢ ( 𝐹 : 𝐴 –1-1-onto→ 𝐵  ↔  ( 𝐹 : 𝐴 –1-1→ 𝐵  ∧  𝐹 : 𝐴 –onto→ 𝐵 ) ) | 
						
							| 6 | 3 4 5 | sylanbrc | ⊢ ( ( 𝐹 : 𝐴 –onto→ 𝐵  ∧  Smo  𝐹 )  →  𝐹 : 𝐴 –1-1-onto→ 𝐵 ) | 
						
							| 7 | 6 | adantl | ⊢ ( ( ( Ord  𝐴  ∧  𝐵  ⊆  On )  ∧  ( 𝐹 : 𝐴 –onto→ 𝐵  ∧  Smo  𝐹 ) )  →  𝐹 : 𝐴 –1-1-onto→ 𝐵 ) | 
						
							| 8 |  | fofn | ⊢ ( 𝐹 : 𝐴 –onto→ 𝐵  →  𝐹  Fn  𝐴 ) | 
						
							| 9 |  | smoord | ⊢ ( ( ( 𝐹  Fn  𝐴  ∧  Smo  𝐹 )  ∧  ( 𝑥  ∈  𝐴  ∧  𝑦  ∈  𝐴 ) )  →  ( 𝑥  ∈  𝑦  ↔  ( 𝐹 ‘ 𝑥 )  ∈  ( 𝐹 ‘ 𝑦 ) ) ) | 
						
							| 10 |  | epel | ⊢ ( 𝑥  E  𝑦  ↔  𝑥  ∈  𝑦 ) | 
						
							| 11 |  | fvex | ⊢ ( 𝐹 ‘ 𝑦 )  ∈  V | 
						
							| 12 | 11 | epeli | ⊢ ( ( 𝐹 ‘ 𝑥 )  E  ( 𝐹 ‘ 𝑦 )  ↔  ( 𝐹 ‘ 𝑥 )  ∈  ( 𝐹 ‘ 𝑦 ) ) | 
						
							| 13 | 9 10 12 | 3bitr4g | ⊢ ( ( ( 𝐹  Fn  𝐴  ∧  Smo  𝐹 )  ∧  ( 𝑥  ∈  𝐴  ∧  𝑦  ∈  𝐴 ) )  →  ( 𝑥  E  𝑦  ↔  ( 𝐹 ‘ 𝑥 )  E  ( 𝐹 ‘ 𝑦 ) ) ) | 
						
							| 14 | 13 | ralrimivva | ⊢ ( ( 𝐹  Fn  𝐴  ∧  Smo  𝐹 )  →  ∀ 𝑥  ∈  𝐴 ∀ 𝑦  ∈  𝐴 ( 𝑥  E  𝑦  ↔  ( 𝐹 ‘ 𝑥 )  E  ( 𝐹 ‘ 𝑦 ) ) ) | 
						
							| 15 | 8 14 | sylan | ⊢ ( ( 𝐹 : 𝐴 –onto→ 𝐵  ∧  Smo  𝐹 )  →  ∀ 𝑥  ∈  𝐴 ∀ 𝑦  ∈  𝐴 ( 𝑥  E  𝑦  ↔  ( 𝐹 ‘ 𝑥 )  E  ( 𝐹 ‘ 𝑦 ) ) ) | 
						
							| 16 | 15 | adantl | ⊢ ( ( ( Ord  𝐴  ∧  𝐵  ⊆  On )  ∧  ( 𝐹 : 𝐴 –onto→ 𝐵  ∧  Smo  𝐹 ) )  →  ∀ 𝑥  ∈  𝐴 ∀ 𝑦  ∈  𝐴 ( 𝑥  E  𝑦  ↔  ( 𝐹 ‘ 𝑥 )  E  ( 𝐹 ‘ 𝑦 ) ) ) | 
						
							| 17 |  | df-isom | ⊢ ( 𝐹  Isom   E  ,   E  ( 𝐴 ,  𝐵 )  ↔  ( 𝐹 : 𝐴 –1-1-onto→ 𝐵  ∧  ∀ 𝑥  ∈  𝐴 ∀ 𝑦  ∈  𝐴 ( 𝑥  E  𝑦  ↔  ( 𝐹 ‘ 𝑥 )  E  ( 𝐹 ‘ 𝑦 ) ) ) ) | 
						
							| 18 | 7 16 17 | sylanbrc | ⊢ ( ( ( Ord  𝐴  ∧  𝐵  ⊆  On )  ∧  ( 𝐹 : 𝐴 –onto→ 𝐵  ∧  Smo  𝐹 ) )  →  𝐹  Isom   E  ,   E  ( 𝐴 ,  𝐵 ) ) | 
						
							| 19 | 18 | ex | ⊢ ( ( Ord  𝐴  ∧  𝐵  ⊆  On )  →  ( ( 𝐹 : 𝐴 –onto→ 𝐵  ∧  Smo  𝐹 )  →  𝐹  Isom   E  ,   E  ( 𝐴 ,  𝐵 ) ) ) | 
						
							| 20 |  | isof1o | ⊢ ( 𝐹  Isom   E  ,   E  ( 𝐴 ,  𝐵 )  →  𝐹 : 𝐴 –1-1-onto→ 𝐵 ) | 
						
							| 21 |  | f1ofo | ⊢ ( 𝐹 : 𝐴 –1-1-onto→ 𝐵  →  𝐹 : 𝐴 –onto→ 𝐵 ) | 
						
							| 22 | 20 21 | syl | ⊢ ( 𝐹  Isom   E  ,   E  ( 𝐴 ,  𝐵 )  →  𝐹 : 𝐴 –onto→ 𝐵 ) | 
						
							| 23 | 22 | 3ad2ant1 | ⊢ ( ( 𝐹  Isom   E  ,   E  ( 𝐴 ,  𝐵 )  ∧  Ord  𝐴  ∧  𝐵  ⊆  On )  →  𝐹 : 𝐴 –onto→ 𝐵 ) | 
						
							| 24 |  | smoiso | ⊢ ( ( 𝐹  Isom   E  ,   E  ( 𝐴 ,  𝐵 )  ∧  Ord  𝐴  ∧  𝐵  ⊆  On )  →  Smo  𝐹 ) | 
						
							| 25 | 23 24 | jca | ⊢ ( ( 𝐹  Isom   E  ,   E  ( 𝐴 ,  𝐵 )  ∧  Ord  𝐴  ∧  𝐵  ⊆  On )  →  ( 𝐹 : 𝐴 –onto→ 𝐵  ∧  Smo  𝐹 ) ) | 
						
							| 26 | 25 | 3expib | ⊢ ( 𝐹  Isom   E  ,   E  ( 𝐴 ,  𝐵 )  →  ( ( Ord  𝐴  ∧  𝐵  ⊆  On )  →  ( 𝐹 : 𝐴 –onto→ 𝐵  ∧  Smo  𝐹 ) ) ) | 
						
							| 27 | 26 | com12 | ⊢ ( ( Ord  𝐴  ∧  𝐵  ⊆  On )  →  ( 𝐹  Isom   E  ,   E  ( 𝐴 ,  𝐵 )  →  ( 𝐹 : 𝐴 –onto→ 𝐵  ∧  Smo  𝐹 ) ) ) | 
						
							| 28 | 19 27 | impbid | ⊢ ( ( Ord  𝐴  ∧  𝐵  ⊆  On )  →  ( ( 𝐹 : 𝐴 –onto→ 𝐵  ∧  Smo  𝐹 )  ↔  𝐹  Isom   E  ,   E  ( 𝐴 ,  𝐵 ) ) ) |