| Step | Hyp | Ref | Expression | 
						
							| 1 |  | f1owe.1 | ⊢ 𝑅  =  { 〈 𝑥 ,  𝑦 〉  ∣  ( 𝐹 ‘ 𝑥 ) 𝑆 ( 𝐹 ‘ 𝑦 ) } | 
						
							| 2 |  | fveq2 | ⊢ ( 𝑥  =  𝑧  →  ( 𝐹 ‘ 𝑥 )  =  ( 𝐹 ‘ 𝑧 ) ) | 
						
							| 3 | 2 | breq1d | ⊢ ( 𝑥  =  𝑧  →  ( ( 𝐹 ‘ 𝑥 ) 𝑆 ( 𝐹 ‘ 𝑦 )  ↔  ( 𝐹 ‘ 𝑧 ) 𝑆 ( 𝐹 ‘ 𝑦 ) ) ) | 
						
							| 4 |  | fveq2 | ⊢ ( 𝑦  =  𝑤  →  ( 𝐹 ‘ 𝑦 )  =  ( 𝐹 ‘ 𝑤 ) ) | 
						
							| 5 | 4 | breq2d | ⊢ ( 𝑦  =  𝑤  →  ( ( 𝐹 ‘ 𝑧 ) 𝑆 ( 𝐹 ‘ 𝑦 )  ↔  ( 𝐹 ‘ 𝑧 ) 𝑆 ( 𝐹 ‘ 𝑤 ) ) ) | 
						
							| 6 | 3 5 1 | brabg | ⊢ ( ( 𝑧  ∈  𝐴  ∧  𝑤  ∈  𝐴 )  →  ( 𝑧 𝑅 𝑤  ↔  ( 𝐹 ‘ 𝑧 ) 𝑆 ( 𝐹 ‘ 𝑤 ) ) ) | 
						
							| 7 | 6 | rgen2 | ⊢ ∀ 𝑧  ∈  𝐴 ∀ 𝑤  ∈  𝐴 ( 𝑧 𝑅 𝑤  ↔  ( 𝐹 ‘ 𝑧 ) 𝑆 ( 𝐹 ‘ 𝑤 ) ) | 
						
							| 8 |  | df-isom | ⊢ ( 𝐹  Isom  𝑅 ,  𝑆 ( 𝐴 ,  𝐵 )  ↔  ( 𝐹 : 𝐴 –1-1-onto→ 𝐵  ∧  ∀ 𝑧  ∈  𝐴 ∀ 𝑤  ∈  𝐴 ( 𝑧 𝑅 𝑤  ↔  ( 𝐹 ‘ 𝑧 ) 𝑆 ( 𝐹 ‘ 𝑤 ) ) ) ) | 
						
							| 9 |  | isowe | ⊢ ( 𝐹  Isom  𝑅 ,  𝑆 ( 𝐴 ,  𝐵 )  →  ( 𝑅  We  𝐴  ↔  𝑆  We  𝐵 ) ) | 
						
							| 10 | 8 9 | sylbir | ⊢ ( ( 𝐹 : 𝐴 –1-1-onto→ 𝐵  ∧  ∀ 𝑧  ∈  𝐴 ∀ 𝑤  ∈  𝐴 ( 𝑧 𝑅 𝑤  ↔  ( 𝐹 ‘ 𝑧 ) 𝑆 ( 𝐹 ‘ 𝑤 ) ) )  →  ( 𝑅  We  𝐴  ↔  𝑆  We  𝐵 ) ) | 
						
							| 11 | 7 10 | mpan2 | ⊢ ( 𝐹 : 𝐴 –1-1-onto→ 𝐵  →  ( 𝑅  We  𝐴  ↔  𝑆  We  𝐵 ) ) | 
						
							| 12 | 11 | biimprd | ⊢ ( 𝐹 : 𝐴 –1-1-onto→ 𝐵  →  ( 𝑆  We  𝐵  →  𝑅  We  𝐴 ) ) |