| Step | Hyp | Ref | Expression | 
						
							| 1 |  | dfrecs3 | ⊢ recs ( 𝐹 )  =  ∪  { 𝑓  ∣  ∃ 𝑥  ∈  On ( 𝑓  Fn  𝑥  ∧  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) } | 
						
							| 2 |  | elin | ⊢ ( 𝑓  ∈  (  Funs   ∩  ( ◡ Domain  “  On ) )  ↔  ( 𝑓  ∈   Funs   ∧  𝑓  ∈  ( ◡ Domain  “  On ) ) ) | 
						
							| 3 |  | vex | ⊢ 𝑓  ∈  V | 
						
							| 4 | 3 | elfuns | ⊢ ( 𝑓  ∈   Funs   ↔  Fun  𝑓 ) | 
						
							| 5 |  | vex | ⊢ 𝑥  ∈  V | 
						
							| 6 | 5 3 | brcnv | ⊢ ( 𝑥 ◡ Domain 𝑓  ↔  𝑓 Domain 𝑥 ) | 
						
							| 7 | 3 5 | brdomain | ⊢ ( 𝑓 Domain 𝑥  ↔  𝑥  =  dom  𝑓 ) | 
						
							| 8 | 6 7 | bitri | ⊢ ( 𝑥 ◡ Domain 𝑓  ↔  𝑥  =  dom  𝑓 ) | 
						
							| 9 | 8 | rexbii | ⊢ ( ∃ 𝑥  ∈  On 𝑥 ◡ Domain 𝑓  ↔  ∃ 𝑥  ∈  On 𝑥  =  dom  𝑓 ) | 
						
							| 10 | 3 | elima | ⊢ ( 𝑓  ∈  ( ◡ Domain  “  On )  ↔  ∃ 𝑥  ∈  On 𝑥 ◡ Domain 𝑓 ) | 
						
							| 11 |  | risset | ⊢ ( dom  𝑓  ∈  On  ↔  ∃ 𝑥  ∈  On 𝑥  =  dom  𝑓 ) | 
						
							| 12 | 9 10 11 | 3bitr4i | ⊢ ( 𝑓  ∈  ( ◡ Domain  “  On )  ↔  dom  𝑓  ∈  On ) | 
						
							| 13 | 4 12 | anbi12i | ⊢ ( ( 𝑓  ∈   Funs   ∧  𝑓  ∈  ( ◡ Domain  “  On ) )  ↔  ( Fun  𝑓  ∧  dom  𝑓  ∈  On ) ) | 
						
							| 14 | 2 13 | bitri | ⊢ ( 𝑓  ∈  (  Funs   ∩  ( ◡ Domain  “  On ) )  ↔  ( Fun  𝑓  ∧  dom  𝑓  ∈  On ) ) | 
						
							| 15 | 3 | eldm | ⊢ ( 𝑓  ∈  dom  ( ( ◡  E   ∘  Domain )  ∖   Fix  ( ◡ Apply  ∘  ( FullFun 𝐹  ∘  Restrict ) ) )  ↔  ∃ 𝑦 𝑓 ( ( ◡  E   ∘  Domain )  ∖   Fix  ( ◡ Apply  ∘  ( FullFun 𝐹  ∘  Restrict ) ) ) 𝑦 ) | 
						
							| 16 |  | brdif | ⊢ ( 𝑓 ( ( ◡  E   ∘  Domain )  ∖   Fix  ( ◡ Apply  ∘  ( FullFun 𝐹  ∘  Restrict ) ) ) 𝑦  ↔  ( 𝑓 ( ◡  E   ∘  Domain ) 𝑦  ∧  ¬  𝑓  Fix  ( ◡ Apply  ∘  ( FullFun 𝐹  ∘  Restrict ) ) 𝑦 ) ) | 
						
							| 17 |  | vex | ⊢ 𝑦  ∈  V | 
						
							| 18 | 3 17 | brco | ⊢ ( 𝑓 ( ◡  E   ∘  Domain ) 𝑦  ↔  ∃ 𝑥 ( 𝑓 Domain 𝑥  ∧  𝑥 ◡  E  𝑦 ) ) | 
						
							| 19 | 7 | anbi1i | ⊢ ( ( 𝑓 Domain 𝑥  ∧  𝑥 ◡  E  𝑦 )  ↔  ( 𝑥  =  dom  𝑓  ∧  𝑥 ◡  E  𝑦 ) ) | 
						
							| 20 | 19 | exbii | ⊢ ( ∃ 𝑥 ( 𝑓 Domain 𝑥  ∧  𝑥 ◡  E  𝑦 )  ↔  ∃ 𝑥 ( 𝑥  =  dom  𝑓  ∧  𝑥 ◡  E  𝑦 ) ) | 
						
							| 21 | 3 | dmex | ⊢ dom  𝑓  ∈  V | 
						
							| 22 |  | breq1 | ⊢ ( 𝑥  =  dom  𝑓  →  ( 𝑥 ◡  E  𝑦  ↔  dom  𝑓 ◡  E  𝑦 ) ) | 
						
							| 23 | 21 22 | ceqsexv | ⊢ ( ∃ 𝑥 ( 𝑥  =  dom  𝑓  ∧  𝑥 ◡  E  𝑦 )  ↔  dom  𝑓 ◡  E  𝑦 ) | 
						
							| 24 | 20 23 | bitri | ⊢ ( ∃ 𝑥 ( 𝑓 Domain 𝑥  ∧  𝑥 ◡  E  𝑦 )  ↔  dom  𝑓 ◡  E  𝑦 ) | 
						
							| 25 | 21 17 | brcnv | ⊢ ( dom  𝑓 ◡  E  𝑦  ↔  𝑦  E  dom  𝑓 ) | 
						
							| 26 | 21 | epeli | ⊢ ( 𝑦  E  dom  𝑓  ↔  𝑦  ∈  dom  𝑓 ) | 
						
							| 27 | 25 26 | bitri | ⊢ ( dom  𝑓 ◡  E  𝑦  ↔  𝑦  ∈  dom  𝑓 ) | 
						
							| 28 | 18 24 27 | 3bitri | ⊢ ( 𝑓 ( ◡  E   ∘  Domain ) 𝑦  ↔  𝑦  ∈  dom  𝑓 ) | 
						
							| 29 |  | df-br | ⊢ ( 𝑓  Fix  ( ◡ Apply  ∘  ( FullFun 𝐹  ∘  Restrict ) ) 𝑦  ↔  〈 𝑓 ,  𝑦 〉  ∈   Fix  ( ◡ Apply  ∘  ( FullFun 𝐹  ∘  Restrict ) ) ) | 
						
							| 30 |  | opex | ⊢ 〈 𝑓 ,  𝑦 〉  ∈  V | 
						
							| 31 | 30 | elfix | ⊢ ( 〈 𝑓 ,  𝑦 〉  ∈   Fix  ( ◡ Apply  ∘  ( FullFun 𝐹  ∘  Restrict ) )  ↔  〈 𝑓 ,  𝑦 〉 ( ◡ Apply  ∘  ( FullFun 𝐹  ∘  Restrict ) ) 〈 𝑓 ,  𝑦 〉 ) | 
						
							| 32 | 30 30 | brco | ⊢ ( 〈 𝑓 ,  𝑦 〉 ( ◡ Apply  ∘  ( FullFun 𝐹  ∘  Restrict ) ) 〈 𝑓 ,  𝑦 〉  ↔  ∃ 𝑥 ( 〈 𝑓 ,  𝑦 〉 ( FullFun 𝐹  ∘  Restrict ) 𝑥  ∧  𝑥 ◡ Apply 〈 𝑓 ,  𝑦 〉 ) ) | 
						
							| 33 |  | ancom | ⊢ ( ( 〈 𝑓 ,  𝑦 〉 ( FullFun 𝐹  ∘  Restrict ) 𝑥  ∧  𝑥 ◡ Apply 〈 𝑓 ,  𝑦 〉 )  ↔  ( 𝑥 ◡ Apply 〈 𝑓 ,  𝑦 〉  ∧  〈 𝑓 ,  𝑦 〉 ( FullFun 𝐹  ∘  Restrict ) 𝑥 ) ) | 
						
							| 34 | 5 30 | brcnv | ⊢ ( 𝑥 ◡ Apply 〈 𝑓 ,  𝑦 〉  ↔  〈 𝑓 ,  𝑦 〉 Apply 𝑥 ) | 
						
							| 35 | 3 17 5 | brapply | ⊢ ( 〈 𝑓 ,  𝑦 〉 Apply 𝑥  ↔  𝑥  =  ( 𝑓 ‘ 𝑦 ) ) | 
						
							| 36 | 34 35 | bitri | ⊢ ( 𝑥 ◡ Apply 〈 𝑓 ,  𝑦 〉  ↔  𝑥  =  ( 𝑓 ‘ 𝑦 ) ) | 
						
							| 37 | 36 | anbi1i | ⊢ ( ( 𝑥 ◡ Apply 〈 𝑓 ,  𝑦 〉  ∧  〈 𝑓 ,  𝑦 〉 ( FullFun 𝐹  ∘  Restrict ) 𝑥 )  ↔  ( 𝑥  =  ( 𝑓 ‘ 𝑦 )  ∧  〈 𝑓 ,  𝑦 〉 ( FullFun 𝐹  ∘  Restrict ) 𝑥 ) ) | 
						
							| 38 | 33 37 | bitri | ⊢ ( ( 〈 𝑓 ,  𝑦 〉 ( FullFun 𝐹  ∘  Restrict ) 𝑥  ∧  𝑥 ◡ Apply 〈 𝑓 ,  𝑦 〉 )  ↔  ( 𝑥  =  ( 𝑓 ‘ 𝑦 )  ∧  〈 𝑓 ,  𝑦 〉 ( FullFun 𝐹  ∘  Restrict ) 𝑥 ) ) | 
						
							| 39 | 38 | exbii | ⊢ ( ∃ 𝑥 ( 〈 𝑓 ,  𝑦 〉 ( FullFun 𝐹  ∘  Restrict ) 𝑥  ∧  𝑥 ◡ Apply 〈 𝑓 ,  𝑦 〉 )  ↔  ∃ 𝑥 ( 𝑥  =  ( 𝑓 ‘ 𝑦 )  ∧  〈 𝑓 ,  𝑦 〉 ( FullFun 𝐹  ∘  Restrict ) 𝑥 ) ) | 
						
							| 40 |  | fvex | ⊢ ( 𝑓 ‘ 𝑦 )  ∈  V | 
						
							| 41 |  | breq2 | ⊢ ( 𝑥  =  ( 𝑓 ‘ 𝑦 )  →  ( 〈 𝑓 ,  𝑦 〉 ( FullFun 𝐹  ∘  Restrict ) 𝑥  ↔  〈 𝑓 ,  𝑦 〉 ( FullFun 𝐹  ∘  Restrict ) ( 𝑓 ‘ 𝑦 ) ) ) | 
						
							| 42 | 40 41 | ceqsexv | ⊢ ( ∃ 𝑥 ( 𝑥  =  ( 𝑓 ‘ 𝑦 )  ∧  〈 𝑓 ,  𝑦 〉 ( FullFun 𝐹  ∘  Restrict ) 𝑥 )  ↔  〈 𝑓 ,  𝑦 〉 ( FullFun 𝐹  ∘  Restrict ) ( 𝑓 ‘ 𝑦 ) ) | 
						
							| 43 | 39 42 | bitri | ⊢ ( ∃ 𝑥 ( 〈 𝑓 ,  𝑦 〉 ( FullFun 𝐹  ∘  Restrict ) 𝑥  ∧  𝑥 ◡ Apply 〈 𝑓 ,  𝑦 〉 )  ↔  〈 𝑓 ,  𝑦 〉 ( FullFun 𝐹  ∘  Restrict ) ( 𝑓 ‘ 𝑦 ) ) | 
						
							| 44 | 30 40 | brco | ⊢ ( 〈 𝑓 ,  𝑦 〉 ( FullFun 𝐹  ∘  Restrict ) ( 𝑓 ‘ 𝑦 )  ↔  ∃ 𝑥 ( 〈 𝑓 ,  𝑦 〉 Restrict 𝑥  ∧  𝑥 FullFun 𝐹 ( 𝑓 ‘ 𝑦 ) ) ) | 
						
							| 45 | 3 17 5 | brrestrict | ⊢ ( 〈 𝑓 ,  𝑦 〉 Restrict 𝑥  ↔  𝑥  =  ( 𝑓  ↾  𝑦 ) ) | 
						
							| 46 | 45 | anbi1i | ⊢ ( ( 〈 𝑓 ,  𝑦 〉 Restrict 𝑥  ∧  𝑥 FullFun 𝐹 ( 𝑓 ‘ 𝑦 ) )  ↔  ( 𝑥  =  ( 𝑓  ↾  𝑦 )  ∧  𝑥 FullFun 𝐹 ( 𝑓 ‘ 𝑦 ) ) ) | 
						
							| 47 | 46 | exbii | ⊢ ( ∃ 𝑥 ( 〈 𝑓 ,  𝑦 〉 Restrict 𝑥  ∧  𝑥 FullFun 𝐹 ( 𝑓 ‘ 𝑦 ) )  ↔  ∃ 𝑥 ( 𝑥  =  ( 𝑓  ↾  𝑦 )  ∧  𝑥 FullFun 𝐹 ( 𝑓 ‘ 𝑦 ) ) ) | 
						
							| 48 | 3 | resex | ⊢ ( 𝑓  ↾  𝑦 )  ∈  V | 
						
							| 49 |  | breq1 | ⊢ ( 𝑥  =  ( 𝑓  ↾  𝑦 )  →  ( 𝑥 FullFun 𝐹 ( 𝑓 ‘ 𝑦 )  ↔  ( 𝑓  ↾  𝑦 ) FullFun 𝐹 ( 𝑓 ‘ 𝑦 ) ) ) | 
						
							| 50 | 48 49 | ceqsexv | ⊢ ( ∃ 𝑥 ( 𝑥  =  ( 𝑓  ↾  𝑦 )  ∧  𝑥 FullFun 𝐹 ( 𝑓 ‘ 𝑦 ) )  ↔  ( 𝑓  ↾  𝑦 ) FullFun 𝐹 ( 𝑓 ‘ 𝑦 ) ) | 
						
							| 51 | 47 50 | bitri | ⊢ ( ∃ 𝑥 ( 〈 𝑓 ,  𝑦 〉 Restrict 𝑥  ∧  𝑥 FullFun 𝐹 ( 𝑓 ‘ 𝑦 ) )  ↔  ( 𝑓  ↾  𝑦 ) FullFun 𝐹 ( 𝑓 ‘ 𝑦 ) ) | 
						
							| 52 | 48 40 | brfullfun | ⊢ ( ( 𝑓  ↾  𝑦 ) FullFun 𝐹 ( 𝑓 ‘ 𝑦 )  ↔  ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) | 
						
							| 53 | 44 51 52 | 3bitri | ⊢ ( 〈 𝑓 ,  𝑦 〉 ( FullFun 𝐹  ∘  Restrict ) ( 𝑓 ‘ 𝑦 )  ↔  ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) | 
						
							| 54 | 32 43 53 | 3bitri | ⊢ ( 〈 𝑓 ,  𝑦 〉 ( ◡ Apply  ∘  ( FullFun 𝐹  ∘  Restrict ) ) 〈 𝑓 ,  𝑦 〉  ↔  ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) | 
						
							| 55 | 29 31 54 | 3bitri | ⊢ ( 𝑓  Fix  ( ◡ Apply  ∘  ( FullFun 𝐹  ∘  Restrict ) ) 𝑦  ↔  ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) | 
						
							| 56 | 55 | notbii | ⊢ ( ¬  𝑓  Fix  ( ◡ Apply  ∘  ( FullFun 𝐹  ∘  Restrict ) ) 𝑦  ↔  ¬  ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) | 
						
							| 57 | 28 56 | anbi12i | ⊢ ( ( 𝑓 ( ◡  E   ∘  Domain ) 𝑦  ∧  ¬  𝑓  Fix  ( ◡ Apply  ∘  ( FullFun 𝐹  ∘  Restrict ) ) 𝑦 )  ↔  ( 𝑦  ∈  dom  𝑓  ∧  ¬  ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) ) | 
						
							| 58 | 16 57 | bitri | ⊢ ( 𝑓 ( ( ◡  E   ∘  Domain )  ∖   Fix  ( ◡ Apply  ∘  ( FullFun 𝐹  ∘  Restrict ) ) ) 𝑦  ↔  ( 𝑦  ∈  dom  𝑓  ∧  ¬  ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) ) | 
						
							| 59 | 58 | exbii | ⊢ ( ∃ 𝑦 𝑓 ( ( ◡  E   ∘  Domain )  ∖   Fix  ( ◡ Apply  ∘  ( FullFun 𝐹  ∘  Restrict ) ) ) 𝑦  ↔  ∃ 𝑦 ( 𝑦  ∈  dom  𝑓  ∧  ¬  ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) ) | 
						
							| 60 | 15 59 | bitri | ⊢ ( 𝑓  ∈  dom  ( ( ◡  E   ∘  Domain )  ∖   Fix  ( ◡ Apply  ∘  ( FullFun 𝐹  ∘  Restrict ) ) )  ↔  ∃ 𝑦 ( 𝑦  ∈  dom  𝑓  ∧  ¬  ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) ) | 
						
							| 61 |  | df-rex | ⊢ ( ∃ 𝑦  ∈  dom  𝑓 ¬  ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) )  ↔  ∃ 𝑦 ( 𝑦  ∈  dom  𝑓  ∧  ¬  ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) ) | 
						
							| 62 |  | rexnal | ⊢ ( ∃ 𝑦  ∈  dom  𝑓 ¬  ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) )  ↔  ¬  ∀ 𝑦  ∈  dom  𝑓 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) | 
						
							| 63 | 60 61 62 | 3bitr2ri | ⊢ ( ¬  ∀ 𝑦  ∈  dom  𝑓 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) )  ↔  𝑓  ∈  dom  ( ( ◡  E   ∘  Domain )  ∖   Fix  ( ◡ Apply  ∘  ( FullFun 𝐹  ∘  Restrict ) ) ) ) | 
						
							| 64 | 63 | con1bii | ⊢ ( ¬  𝑓  ∈  dom  ( ( ◡  E   ∘  Domain )  ∖   Fix  ( ◡ Apply  ∘  ( FullFun 𝐹  ∘  Restrict ) ) )  ↔  ∀ 𝑦  ∈  dom  𝑓 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) | 
						
							| 65 | 14 64 | anbi12i | ⊢ ( ( 𝑓  ∈  (  Funs   ∩  ( ◡ Domain  “  On ) )  ∧  ¬  𝑓  ∈  dom  ( ( ◡  E   ∘  Domain )  ∖   Fix  ( ◡ Apply  ∘  ( FullFun 𝐹  ∘  Restrict ) ) ) )  ↔  ( ( Fun  𝑓  ∧  dom  𝑓  ∈  On )  ∧  ∀ 𝑦  ∈  dom  𝑓 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) ) | 
						
							| 66 |  | anass | ⊢ ( ( ( Fun  𝑓  ∧  dom  𝑓  ∈  On )  ∧  ∀ 𝑦  ∈  dom  𝑓 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) )  ↔  ( Fun  𝑓  ∧  ( dom  𝑓  ∈  On  ∧  ∀ 𝑦  ∈  dom  𝑓 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) ) ) | 
						
							| 67 | 65 66 | bitri | ⊢ ( ( 𝑓  ∈  (  Funs   ∩  ( ◡ Domain  “  On ) )  ∧  ¬  𝑓  ∈  dom  ( ( ◡  E   ∘  Domain )  ∖   Fix  ( ◡ Apply  ∘  ( FullFun 𝐹  ∘  Restrict ) ) ) )  ↔  ( Fun  𝑓  ∧  ( dom  𝑓  ∈  On  ∧  ∀ 𝑦  ∈  dom  𝑓 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) ) ) | 
						
							| 68 |  | eleq1 | ⊢ ( 𝑥  =  dom  𝑓  →  ( 𝑥  ∈  On  ↔  dom  𝑓  ∈  On ) ) | 
						
							| 69 |  | raleq | ⊢ ( 𝑥  =  dom  𝑓  →  ( ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) )  ↔  ∀ 𝑦  ∈  dom  𝑓 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) ) | 
						
							| 70 | 68 69 | anbi12d | ⊢ ( 𝑥  =  dom  𝑓  →  ( ( 𝑥  ∈  On  ∧  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) )  ↔  ( dom  𝑓  ∈  On  ∧  ∀ 𝑦  ∈  dom  𝑓 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) ) ) | 
						
							| 71 | 70 | anbi2d | ⊢ ( 𝑥  =  dom  𝑓  →  ( ( Fun  𝑓  ∧  ( 𝑥  ∈  On  ∧  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) )  ↔  ( Fun  𝑓  ∧  ( dom  𝑓  ∈  On  ∧  ∀ 𝑦  ∈  dom  𝑓 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) ) ) ) | 
						
							| 72 | 21 71 | ceqsexv | ⊢ ( ∃ 𝑥 ( 𝑥  =  dom  𝑓  ∧  ( Fun  𝑓  ∧  ( 𝑥  ∈  On  ∧  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) ) )  ↔  ( Fun  𝑓  ∧  ( dom  𝑓  ∈  On  ∧  ∀ 𝑦  ∈  dom  𝑓 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) ) ) | 
						
							| 73 |  | df-fn | ⊢ ( 𝑓  Fn  𝑥  ↔  ( Fun  𝑓  ∧  dom  𝑓  =  𝑥 ) ) | 
						
							| 74 |  | eqcom | ⊢ ( dom  𝑓  =  𝑥  ↔  𝑥  =  dom  𝑓 ) | 
						
							| 75 | 74 | anbi2i | ⊢ ( ( Fun  𝑓  ∧  dom  𝑓  =  𝑥 )  ↔  ( Fun  𝑓  ∧  𝑥  =  dom  𝑓 ) ) | 
						
							| 76 |  | ancom | ⊢ ( ( Fun  𝑓  ∧  𝑥  =  dom  𝑓 )  ↔  ( 𝑥  =  dom  𝑓  ∧  Fun  𝑓 ) ) | 
						
							| 77 | 73 75 76 | 3bitri | ⊢ ( 𝑓  Fn  𝑥  ↔  ( 𝑥  =  dom  𝑓  ∧  Fun  𝑓 ) ) | 
						
							| 78 | 77 | anbi1i | ⊢ ( ( 𝑓  Fn  𝑥  ∧  ( 𝑥  ∈  On  ∧  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) )  ↔  ( ( 𝑥  =  dom  𝑓  ∧  Fun  𝑓 )  ∧  ( 𝑥  ∈  On  ∧  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) ) ) | 
						
							| 79 |  | an12 | ⊢ ( ( 𝑓  Fn  𝑥  ∧  ( 𝑥  ∈  On  ∧  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) )  ↔  ( 𝑥  ∈  On  ∧  ( 𝑓  Fn  𝑥  ∧  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) ) ) | 
						
							| 80 |  | anass | ⊢ ( ( ( 𝑥  =  dom  𝑓  ∧  Fun  𝑓 )  ∧  ( 𝑥  ∈  On  ∧  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) )  ↔  ( 𝑥  =  dom  𝑓  ∧  ( Fun  𝑓  ∧  ( 𝑥  ∈  On  ∧  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) ) ) ) | 
						
							| 81 | 78 79 80 | 3bitr3ri | ⊢ ( ( 𝑥  =  dom  𝑓  ∧  ( Fun  𝑓  ∧  ( 𝑥  ∈  On  ∧  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) ) )  ↔  ( 𝑥  ∈  On  ∧  ( 𝑓  Fn  𝑥  ∧  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) ) ) | 
						
							| 82 | 81 | exbii | ⊢ ( ∃ 𝑥 ( 𝑥  =  dom  𝑓  ∧  ( Fun  𝑓  ∧  ( 𝑥  ∈  On  ∧  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) ) )  ↔  ∃ 𝑥 ( 𝑥  ∈  On  ∧  ( 𝑓  Fn  𝑥  ∧  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) ) ) | 
						
							| 83 | 67 72 82 | 3bitr2i | ⊢ ( ( 𝑓  ∈  (  Funs   ∩  ( ◡ Domain  “  On ) )  ∧  ¬  𝑓  ∈  dom  ( ( ◡  E   ∘  Domain )  ∖   Fix  ( ◡ Apply  ∘  ( FullFun 𝐹  ∘  Restrict ) ) ) )  ↔  ∃ 𝑥 ( 𝑥  ∈  On  ∧  ( 𝑓  Fn  𝑥  ∧  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) ) ) | 
						
							| 84 |  | eldif | ⊢ ( 𝑓  ∈  ( (  Funs   ∩  ( ◡ Domain  “  On ) )  ∖  dom  ( ( ◡  E   ∘  Domain )  ∖   Fix  ( ◡ Apply  ∘  ( FullFun 𝐹  ∘  Restrict ) ) ) )  ↔  ( 𝑓  ∈  (  Funs   ∩  ( ◡ Domain  “  On ) )  ∧  ¬  𝑓  ∈  dom  ( ( ◡  E   ∘  Domain )  ∖   Fix  ( ◡ Apply  ∘  ( FullFun 𝐹  ∘  Restrict ) ) ) ) ) | 
						
							| 85 |  | df-rex | ⊢ ( ∃ 𝑥  ∈  On ( 𝑓  Fn  𝑥  ∧  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) )  ↔  ∃ 𝑥 ( 𝑥  ∈  On  ∧  ( 𝑓  Fn  𝑥  ∧  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) ) ) | 
						
							| 86 | 83 84 85 | 3bitr4i | ⊢ ( 𝑓  ∈  ( (  Funs   ∩  ( ◡ Domain  “  On ) )  ∖  dom  ( ( ◡  E   ∘  Domain )  ∖   Fix  ( ◡ Apply  ∘  ( FullFun 𝐹  ∘  Restrict ) ) ) )  ↔  ∃ 𝑥  ∈  On ( 𝑓  Fn  𝑥  ∧  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) ) | 
						
							| 87 | 86 | eqabi | ⊢ ( (  Funs   ∩  ( ◡ Domain  “  On ) )  ∖  dom  ( ( ◡  E   ∘  Domain )  ∖   Fix  ( ◡ Apply  ∘  ( FullFun 𝐹  ∘  Restrict ) ) ) )  =  { 𝑓  ∣  ∃ 𝑥  ∈  On ( 𝑓  Fn  𝑥  ∧  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) } | 
						
							| 88 | 87 | unieqi | ⊢ ∪  ( (  Funs   ∩  ( ◡ Domain  “  On ) )  ∖  dom  ( ( ◡  E   ∘  Domain )  ∖   Fix  ( ◡ Apply  ∘  ( FullFun 𝐹  ∘  Restrict ) ) ) )  =  ∪  { 𝑓  ∣  ∃ 𝑥  ∈  On ( 𝑓  Fn  𝑥  ∧  ∀ 𝑦  ∈  𝑥 ( 𝑓 ‘ 𝑦 )  =  ( 𝐹 ‘ ( 𝑓  ↾  𝑦 ) ) ) } | 
						
							| 89 | 1 88 | eqtr4i | ⊢ recs ( 𝐹 )  =  ∪  ( (  Funs   ∩  ( ◡ Domain  “  On ) )  ∖  dom  ( ( ◡  E   ∘  Domain )  ∖   Fix  ( ◡ Apply  ∘  ( FullFun 𝐹  ∘  Restrict ) ) ) ) |