| Step | 
						Hyp | 
						Ref | 
						Expression | 
					
						
							| 1 | 
							
								
							 | 
							df-br | 
							⊢ ( 𝑥 𝑅 𝑦  ↔  〈 𝑥 ,  𝑦 〉  ∈  𝑅 )  | 
						
						
							| 2 | 
							
								
							 | 
							vex | 
							⊢ 𝑥  ∈  V  | 
						
						
							| 3 | 
							
								
							 | 
							vex | 
							⊢ 𝑦  ∈  V  | 
						
						
							| 4 | 
							
								2 3
							 | 
							opeluu | 
							⊢ ( 〈 𝑥 ,  𝑦 〉  ∈  𝑅  →  ( 𝑥  ∈  ∪  ∪  𝑅  ∧  𝑦  ∈  ∪  ∪  𝑅 ) )  | 
						
						
							| 5 | 
							
								1 4
							 | 
							sylbi | 
							⊢ ( 𝑥 𝑅 𝑦  →  ( 𝑥  ∈  ∪  ∪  𝑅  ∧  𝑦  ∈  ∪  ∪  𝑅 ) )  | 
						
						
							| 6 | 
							
								5
							 | 
							simpld | 
							⊢ ( 𝑥 𝑅 𝑦  →  𝑥  ∈  ∪  ∪  𝑅 )  | 
						
						
							| 7 | 
							
								6
							 | 
							adantr | 
							⊢ ( ( 𝑥 𝑅 𝑦  ∧  𝑦 𝑅 𝑥 )  →  𝑥  ∈  ∪  ∪  𝑅 )  | 
						
						
							| 8 | 
							
								7
							 | 
							pm4.71ri | 
							⊢ ( ( 𝑥 𝑅 𝑦  ∧  𝑦 𝑅 𝑥 )  ↔  ( 𝑥  ∈  ∪  ∪  𝑅  ∧  ( 𝑥 𝑅 𝑦  ∧  𝑦 𝑅 𝑥 ) ) )  | 
						
						
							| 9 | 
							
								8
							 | 
							bibi1i | 
							⊢ ( ( ( 𝑥 𝑅 𝑦  ∧  𝑦 𝑅 𝑥 )  ↔  ( 𝑥  ∈  ∪  ∪  𝑅  ∧  𝑥  =  𝑦 ) )  ↔  ( ( 𝑥  ∈  ∪  ∪  𝑅  ∧  ( 𝑥 𝑅 𝑦  ∧  𝑦 𝑅 𝑥 ) )  ↔  ( 𝑥  ∈  ∪  ∪  𝑅  ∧  𝑥  =  𝑦 ) ) )  | 
						
						
							| 10 | 
							
								
							 | 
							elin | 
							⊢ ( 〈 𝑥 ,  𝑦 〉  ∈  ( 𝑅  ∩  ◡ 𝑅 )  ↔  ( 〈 𝑥 ,  𝑦 〉  ∈  𝑅  ∧  〈 𝑥 ,  𝑦 〉  ∈  ◡ 𝑅 ) )  | 
						
						
							| 11 | 
							
								2 3
							 | 
							brcnv | 
							⊢ ( 𝑥 ◡ 𝑅 𝑦  ↔  𝑦 𝑅 𝑥 )  | 
						
						
							| 12 | 
							
								
							 | 
							df-br | 
							⊢ ( 𝑥 ◡ 𝑅 𝑦  ↔  〈 𝑥 ,  𝑦 〉  ∈  ◡ 𝑅 )  | 
						
						
							| 13 | 
							
								11 12
							 | 
							bitr3i | 
							⊢ ( 𝑦 𝑅 𝑥  ↔  〈 𝑥 ,  𝑦 〉  ∈  ◡ 𝑅 )  | 
						
						
							| 14 | 
							
								1 13
							 | 
							anbi12i | 
							⊢ ( ( 𝑥 𝑅 𝑦  ∧  𝑦 𝑅 𝑥 )  ↔  ( 〈 𝑥 ,  𝑦 〉  ∈  𝑅  ∧  〈 𝑥 ,  𝑦 〉  ∈  ◡ 𝑅 ) )  | 
						
						
							| 15 | 
							
								10 14
							 | 
							bitr4i | 
							⊢ ( 〈 𝑥 ,  𝑦 〉  ∈  ( 𝑅  ∩  ◡ 𝑅 )  ↔  ( 𝑥 𝑅 𝑦  ∧  𝑦 𝑅 𝑥 ) )  | 
						
						
							| 16 | 
							
								3
							 | 
							opelresi | 
							⊢ ( 〈 𝑥 ,  𝑦 〉  ∈  (  I   ↾  ∪  ∪  𝑅 )  ↔  ( 𝑥  ∈  ∪  ∪  𝑅  ∧  〈 𝑥 ,  𝑦 〉  ∈   I  ) )  | 
						
						
							| 17 | 
							
								
							 | 
							df-br | 
							⊢ ( 𝑥  I  𝑦  ↔  〈 𝑥 ,  𝑦 〉  ∈   I  )  | 
						
						
							| 18 | 
							
								3
							 | 
							ideq | 
							⊢ ( 𝑥  I  𝑦  ↔  𝑥  =  𝑦 )  | 
						
						
							| 19 | 
							
								17 18
							 | 
							bitr3i | 
							⊢ ( 〈 𝑥 ,  𝑦 〉  ∈   I   ↔  𝑥  =  𝑦 )  | 
						
						
							| 20 | 
							
								19
							 | 
							anbi2i | 
							⊢ ( ( 𝑥  ∈  ∪  ∪  𝑅  ∧  〈 𝑥 ,  𝑦 〉  ∈   I  )  ↔  ( 𝑥  ∈  ∪  ∪  𝑅  ∧  𝑥  =  𝑦 ) )  | 
						
						
							| 21 | 
							
								16 20
							 | 
							bitri | 
							⊢ ( 〈 𝑥 ,  𝑦 〉  ∈  (  I   ↾  ∪  ∪  𝑅 )  ↔  ( 𝑥  ∈  ∪  ∪  𝑅  ∧  𝑥  =  𝑦 ) )  | 
						
						
							| 22 | 
							
								15 21
							 | 
							bibi12i | 
							⊢ ( ( 〈 𝑥 ,  𝑦 〉  ∈  ( 𝑅  ∩  ◡ 𝑅 )  ↔  〈 𝑥 ,  𝑦 〉  ∈  (  I   ↾  ∪  ∪  𝑅 ) )  ↔  ( ( 𝑥 𝑅 𝑦  ∧  𝑦 𝑅 𝑥 )  ↔  ( 𝑥  ∈  ∪  ∪  𝑅  ∧  𝑥  =  𝑦 ) ) )  | 
						
						
							| 23 | 
							
								
							 | 
							pm5.32 | 
							⊢ ( ( 𝑥  ∈  ∪  ∪  𝑅  →  ( ( 𝑥 𝑅 𝑦  ∧  𝑦 𝑅 𝑥 )  ↔  𝑥  =  𝑦 ) )  ↔  ( ( 𝑥  ∈  ∪  ∪  𝑅  ∧  ( 𝑥 𝑅 𝑦  ∧  𝑦 𝑅 𝑥 ) )  ↔  ( 𝑥  ∈  ∪  ∪  𝑅  ∧  𝑥  =  𝑦 ) ) )  | 
						
						
							| 24 | 
							
								9 22 23
							 | 
							3bitr4i | 
							⊢ ( ( 〈 𝑥 ,  𝑦 〉  ∈  ( 𝑅  ∩  ◡ 𝑅 )  ↔  〈 𝑥 ,  𝑦 〉  ∈  (  I   ↾  ∪  ∪  𝑅 ) )  ↔  ( 𝑥  ∈  ∪  ∪  𝑅  →  ( ( 𝑥 𝑅 𝑦  ∧  𝑦 𝑅 𝑥 )  ↔  𝑥  =  𝑦 ) ) )  | 
						
						
							| 25 | 
							
								24
							 | 
							albii | 
							⊢ ( ∀ 𝑦 ( 〈 𝑥 ,  𝑦 〉  ∈  ( 𝑅  ∩  ◡ 𝑅 )  ↔  〈 𝑥 ,  𝑦 〉  ∈  (  I   ↾  ∪  ∪  𝑅 ) )  ↔  ∀ 𝑦 ( 𝑥  ∈  ∪  ∪  𝑅  →  ( ( 𝑥 𝑅 𝑦  ∧  𝑦 𝑅 𝑥 )  ↔  𝑥  =  𝑦 ) ) )  | 
						
						
							| 26 | 
							
								
							 | 
							19.21v | 
							⊢ ( ∀ 𝑦 ( 𝑥  ∈  ∪  ∪  𝑅  →  ( ( 𝑥 𝑅 𝑦  ∧  𝑦 𝑅 𝑥 )  ↔  𝑥  =  𝑦 ) )  ↔  ( 𝑥  ∈  ∪  ∪  𝑅  →  ∀ 𝑦 ( ( 𝑥 𝑅 𝑦  ∧  𝑦 𝑅 𝑥 )  ↔  𝑥  =  𝑦 ) ) )  | 
						
						
							| 27 | 
							
								25 26
							 | 
							bitri | 
							⊢ ( ∀ 𝑦 ( 〈 𝑥 ,  𝑦 〉  ∈  ( 𝑅  ∩  ◡ 𝑅 )  ↔  〈 𝑥 ,  𝑦 〉  ∈  (  I   ↾  ∪  ∪  𝑅 ) )  ↔  ( 𝑥  ∈  ∪  ∪  𝑅  →  ∀ 𝑦 ( ( 𝑥 𝑅 𝑦  ∧  𝑦 𝑅 𝑥 )  ↔  𝑥  =  𝑦 ) ) )  | 
						
						
							| 28 | 
							
								27
							 | 
							albii | 
							⊢ ( ∀ 𝑥 ∀ 𝑦 ( 〈 𝑥 ,  𝑦 〉  ∈  ( 𝑅  ∩  ◡ 𝑅 )  ↔  〈 𝑥 ,  𝑦 〉  ∈  (  I   ↾  ∪  ∪  𝑅 ) )  ↔  ∀ 𝑥 ( 𝑥  ∈  ∪  ∪  𝑅  →  ∀ 𝑦 ( ( 𝑥 𝑅 𝑦  ∧  𝑦 𝑅 𝑥 )  ↔  𝑥  =  𝑦 ) ) )  | 
						
						
							| 29 | 
							
								
							 | 
							relcnv | 
							⊢ Rel  ◡ 𝑅  | 
						
						
							| 30 | 
							
								
							 | 
							relin2 | 
							⊢ ( Rel  ◡ 𝑅  →  Rel  ( 𝑅  ∩  ◡ 𝑅 ) )  | 
						
						
							| 31 | 
							
								29 30
							 | 
							ax-mp | 
							⊢ Rel  ( 𝑅  ∩  ◡ 𝑅 )  | 
						
						
							| 32 | 
							
								
							 | 
							relres | 
							⊢ Rel  (  I   ↾  ∪  ∪  𝑅 )  | 
						
						
							| 33 | 
							
								
							 | 
							eqrel | 
							⊢ ( ( Rel  ( 𝑅  ∩  ◡ 𝑅 )  ∧  Rel  (  I   ↾  ∪  ∪  𝑅 ) )  →  ( ( 𝑅  ∩  ◡ 𝑅 )  =  (  I   ↾  ∪  ∪  𝑅 )  ↔  ∀ 𝑥 ∀ 𝑦 ( 〈 𝑥 ,  𝑦 〉  ∈  ( 𝑅  ∩  ◡ 𝑅 )  ↔  〈 𝑥 ,  𝑦 〉  ∈  (  I   ↾  ∪  ∪  𝑅 ) ) ) )  | 
						
						
							| 34 | 
							
								31 32 33
							 | 
							mp2an | 
							⊢ ( ( 𝑅  ∩  ◡ 𝑅 )  =  (  I   ↾  ∪  ∪  𝑅 )  ↔  ∀ 𝑥 ∀ 𝑦 ( 〈 𝑥 ,  𝑦 〉  ∈  ( 𝑅  ∩  ◡ 𝑅 )  ↔  〈 𝑥 ,  𝑦 〉  ∈  (  I   ↾  ∪  ∪  𝑅 ) ) )  | 
						
						
							| 35 | 
							
								
							 | 
							df-ral | 
							⊢ ( ∀ 𝑥  ∈  ∪  ∪  𝑅 ∀ 𝑦 ( ( 𝑥 𝑅 𝑦  ∧  𝑦 𝑅 𝑥 )  ↔  𝑥  =  𝑦 )  ↔  ∀ 𝑥 ( 𝑥  ∈  ∪  ∪  𝑅  →  ∀ 𝑦 ( ( 𝑥 𝑅 𝑦  ∧  𝑦 𝑅 𝑥 )  ↔  𝑥  =  𝑦 ) ) )  | 
						
						
							| 36 | 
							
								28 34 35
							 | 
							3bitr4i | 
							⊢ ( ( 𝑅  ∩  ◡ 𝑅 )  =  (  I   ↾  ∪  ∪  𝑅 )  ↔  ∀ 𝑥  ∈  ∪  ∪  𝑅 ∀ 𝑦 ( ( 𝑥 𝑅 𝑦  ∧  𝑦 𝑅 𝑥 )  ↔  𝑥  =  𝑦 ) )  |