| 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 ) ) |