| Step | Hyp | Ref | Expression | 
						
							| 1 |  | df-tpos | ⊢ tpos  𝐹  =  ( 𝐹  ∘  ( 𝑥  ∈  ( ◡ dom  𝐹  ∪  { ∅ } )  ↦  ∪  ◡ { 𝑥 } ) ) | 
						
							| 2 |  | relcnv | ⊢ Rel  ◡ dom  𝐹 | 
						
							| 3 |  | df-rel | ⊢ ( Rel  ◡ dom  𝐹  ↔  ◡ dom  𝐹  ⊆  ( V  ×  V ) ) | 
						
							| 4 | 2 3 | mpbi | ⊢ ◡ dom  𝐹  ⊆  ( V  ×  V ) | 
						
							| 5 |  | unss1 | ⊢ ( ◡ dom  𝐹  ⊆  ( V  ×  V )  →  ( ◡ dom  𝐹  ∪  { ∅ } )  ⊆  ( ( V  ×  V )  ∪  { ∅ } ) ) | 
						
							| 6 |  | resmpt | ⊢ ( ( ◡ dom  𝐹  ∪  { ∅ } )  ⊆  ( ( V  ×  V )  ∪  { ∅ } )  →  ( ( 𝑥  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ↦  ∪  ◡ { 𝑥 } )  ↾  ( ◡ dom  𝐹  ∪  { ∅ } ) )  =  ( 𝑥  ∈  ( ◡ dom  𝐹  ∪  { ∅ } )  ↦  ∪  ◡ { 𝑥 } ) ) | 
						
							| 7 | 4 5 6 | mp2b | ⊢ ( ( 𝑥  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ↦  ∪  ◡ { 𝑥 } )  ↾  ( ◡ dom  𝐹  ∪  { ∅ } ) )  =  ( 𝑥  ∈  ( ◡ dom  𝐹  ∪  { ∅ } )  ↦  ∪  ◡ { 𝑥 } ) | 
						
							| 8 |  | resss | ⊢ ( ( 𝑥  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ↦  ∪  ◡ { 𝑥 } )  ↾  ( ◡ dom  𝐹  ∪  { ∅ } ) )  ⊆  ( 𝑥  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ↦  ∪  ◡ { 𝑥 } ) | 
						
							| 9 | 7 8 | eqsstrri | ⊢ ( 𝑥  ∈  ( ◡ dom  𝐹  ∪  { ∅ } )  ↦  ∪  ◡ { 𝑥 } )  ⊆  ( 𝑥  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ↦  ∪  ◡ { 𝑥 } ) | 
						
							| 10 |  | coss2 | ⊢ ( ( 𝑥  ∈  ( ◡ dom  𝐹  ∪  { ∅ } )  ↦  ∪  ◡ { 𝑥 } )  ⊆  ( 𝑥  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ↦  ∪  ◡ { 𝑥 } )  →  ( 𝐹  ∘  ( 𝑥  ∈  ( ◡ dom  𝐹  ∪  { ∅ } )  ↦  ∪  ◡ { 𝑥 } ) )  ⊆  ( 𝐹  ∘  ( 𝑥  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ↦  ∪  ◡ { 𝑥 } ) ) ) | 
						
							| 11 | 9 10 | ax-mp | ⊢ ( 𝐹  ∘  ( 𝑥  ∈  ( ◡ dom  𝐹  ∪  { ∅ } )  ↦  ∪  ◡ { 𝑥 } ) )  ⊆  ( 𝐹  ∘  ( 𝑥  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ↦  ∪  ◡ { 𝑥 } ) ) | 
						
							| 12 | 1 11 | eqsstri | ⊢ tpos  𝐹  ⊆  ( 𝐹  ∘  ( 𝑥  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ↦  ∪  ◡ { 𝑥 } ) ) | 
						
							| 13 |  | relco | ⊢ Rel  ( 𝐹  ∘  ( 𝑥  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ↦  ∪  ◡ { 𝑥 } ) ) | 
						
							| 14 |  | vex | ⊢ 𝑦  ∈  V | 
						
							| 15 |  | vex | ⊢ 𝑧  ∈  V | 
						
							| 16 | 14 15 | opelco | ⊢ ( 〈 𝑦 ,  𝑧 〉  ∈  ( 𝐹  ∘  ( 𝑥  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ↦  ∪  ◡ { 𝑥 } ) )  ↔  ∃ 𝑤 ( 𝑦 ( 𝑥  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ↦  ∪  ◡ { 𝑥 } ) 𝑤  ∧  𝑤 𝐹 𝑧 ) ) | 
						
							| 17 |  | vex | ⊢ 𝑤  ∈  V | 
						
							| 18 |  | eleq1 | ⊢ ( 𝑥  =  𝑦  →  ( 𝑥  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ↔  𝑦  ∈  ( ( V  ×  V )  ∪  { ∅ } ) ) ) | 
						
							| 19 |  | sneq | ⊢ ( 𝑥  =  𝑦  →  { 𝑥 }  =  { 𝑦 } ) | 
						
							| 20 | 19 | cnveqd | ⊢ ( 𝑥  =  𝑦  →  ◡ { 𝑥 }  =  ◡ { 𝑦 } ) | 
						
							| 21 | 20 | unieqd | ⊢ ( 𝑥  =  𝑦  →  ∪  ◡ { 𝑥 }  =  ∪  ◡ { 𝑦 } ) | 
						
							| 22 | 21 | eqeq2d | ⊢ ( 𝑥  =  𝑦  →  ( 𝑧  =  ∪  ◡ { 𝑥 }  ↔  𝑧  =  ∪  ◡ { 𝑦 } ) ) | 
						
							| 23 | 18 22 | anbi12d | ⊢ ( 𝑥  =  𝑦  →  ( ( 𝑥  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ∧  𝑧  =  ∪  ◡ { 𝑥 } )  ↔  ( 𝑦  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ∧  𝑧  =  ∪  ◡ { 𝑦 } ) ) ) | 
						
							| 24 |  | eqeq1 | ⊢ ( 𝑧  =  𝑤  →  ( 𝑧  =  ∪  ◡ { 𝑦 }  ↔  𝑤  =  ∪  ◡ { 𝑦 } ) ) | 
						
							| 25 | 24 | anbi2d | ⊢ ( 𝑧  =  𝑤  →  ( ( 𝑦  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ∧  𝑧  =  ∪  ◡ { 𝑦 } )  ↔  ( 𝑦  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ∧  𝑤  =  ∪  ◡ { 𝑦 } ) ) ) | 
						
							| 26 |  | df-mpt | ⊢ ( 𝑥  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ↦  ∪  ◡ { 𝑥 } )  =  { 〈 𝑥 ,  𝑧 〉  ∣  ( 𝑥  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ∧  𝑧  =  ∪  ◡ { 𝑥 } ) } | 
						
							| 27 | 14 17 23 25 26 | brab | ⊢ ( 𝑦 ( 𝑥  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ↦  ∪  ◡ { 𝑥 } ) 𝑤  ↔  ( 𝑦  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ∧  𝑤  =  ∪  ◡ { 𝑦 } ) ) | 
						
							| 28 |  | simplr | ⊢ ( ( ( 𝑦  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ∧  𝑤  =  ∪  ◡ { 𝑦 } )  ∧  𝑤 𝐹 𝑧 )  →  𝑤  =  ∪  ◡ { 𝑦 } ) | 
						
							| 29 | 17 15 | breldm | ⊢ ( 𝑤 𝐹 𝑧  →  𝑤  ∈  dom  𝐹 ) | 
						
							| 30 | 29 | adantl | ⊢ ( ( ( 𝑦  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ∧  𝑤  =  ∪  ◡ { 𝑦 } )  ∧  𝑤 𝐹 𝑧 )  →  𝑤  ∈  dom  𝐹 ) | 
						
							| 31 | 28 30 | eqeltrrd | ⊢ ( ( ( 𝑦  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ∧  𝑤  =  ∪  ◡ { 𝑦 } )  ∧  𝑤 𝐹 𝑧 )  →  ∪  ◡ { 𝑦 }  ∈  dom  𝐹 ) | 
						
							| 32 |  | elvv | ⊢ ( 𝑦  ∈  ( V  ×  V )  ↔  ∃ 𝑧 ∃ 𝑤 𝑦  =  〈 𝑧 ,  𝑤 〉 ) | 
						
							| 33 |  | opswap | ⊢ ∪  ◡ { 〈 𝑧 ,  𝑤 〉 }  =  〈 𝑤 ,  𝑧 〉 | 
						
							| 34 | 33 | eleq1i | ⊢ ( ∪  ◡ { 〈 𝑧 ,  𝑤 〉 }  ∈  dom  𝐹  ↔  〈 𝑤 ,  𝑧 〉  ∈  dom  𝐹 ) | 
						
							| 35 | 15 17 | opelcnv | ⊢ ( 〈 𝑧 ,  𝑤 〉  ∈  ◡ dom  𝐹  ↔  〈 𝑤 ,  𝑧 〉  ∈  dom  𝐹 ) | 
						
							| 36 | 34 35 | bitr4i | ⊢ ( ∪  ◡ { 〈 𝑧 ,  𝑤 〉 }  ∈  dom  𝐹  ↔  〈 𝑧 ,  𝑤 〉  ∈  ◡ dom  𝐹 ) | 
						
							| 37 |  | sneq | ⊢ ( 𝑦  =  〈 𝑧 ,  𝑤 〉  →  { 𝑦 }  =  { 〈 𝑧 ,  𝑤 〉 } ) | 
						
							| 38 | 37 | cnveqd | ⊢ ( 𝑦  =  〈 𝑧 ,  𝑤 〉  →  ◡ { 𝑦 }  =  ◡ { 〈 𝑧 ,  𝑤 〉 } ) | 
						
							| 39 | 38 | unieqd | ⊢ ( 𝑦  =  〈 𝑧 ,  𝑤 〉  →  ∪  ◡ { 𝑦 }  =  ∪  ◡ { 〈 𝑧 ,  𝑤 〉 } ) | 
						
							| 40 | 39 | eleq1d | ⊢ ( 𝑦  =  〈 𝑧 ,  𝑤 〉  →  ( ∪  ◡ { 𝑦 }  ∈  dom  𝐹  ↔  ∪  ◡ { 〈 𝑧 ,  𝑤 〉 }  ∈  dom  𝐹 ) ) | 
						
							| 41 |  | eleq1 | ⊢ ( 𝑦  =  〈 𝑧 ,  𝑤 〉  →  ( 𝑦  ∈  ◡ dom  𝐹  ↔  〈 𝑧 ,  𝑤 〉  ∈  ◡ dom  𝐹 ) ) | 
						
							| 42 | 40 41 | bibi12d | ⊢ ( 𝑦  =  〈 𝑧 ,  𝑤 〉  →  ( ( ∪  ◡ { 𝑦 }  ∈  dom  𝐹  ↔  𝑦  ∈  ◡ dom  𝐹 )  ↔  ( ∪  ◡ { 〈 𝑧 ,  𝑤 〉 }  ∈  dom  𝐹  ↔  〈 𝑧 ,  𝑤 〉  ∈  ◡ dom  𝐹 ) ) ) | 
						
							| 43 | 36 42 | mpbiri | ⊢ ( 𝑦  =  〈 𝑧 ,  𝑤 〉  →  ( ∪  ◡ { 𝑦 }  ∈  dom  𝐹  ↔  𝑦  ∈  ◡ dom  𝐹 ) ) | 
						
							| 44 | 43 | exlimivv | ⊢ ( ∃ 𝑧 ∃ 𝑤 𝑦  =  〈 𝑧 ,  𝑤 〉  →  ( ∪  ◡ { 𝑦 }  ∈  dom  𝐹  ↔  𝑦  ∈  ◡ dom  𝐹 ) ) | 
						
							| 45 | 32 44 | sylbi | ⊢ ( 𝑦  ∈  ( V  ×  V )  →  ( ∪  ◡ { 𝑦 }  ∈  dom  𝐹  ↔  𝑦  ∈  ◡ dom  𝐹 ) ) | 
						
							| 46 | 45 | biimpcd | ⊢ ( ∪  ◡ { 𝑦 }  ∈  dom  𝐹  →  ( 𝑦  ∈  ( V  ×  V )  →  𝑦  ∈  ◡ dom  𝐹 ) ) | 
						
							| 47 |  | elun1 | ⊢ ( 𝑦  ∈  ◡ dom  𝐹  →  𝑦  ∈  ( ◡ dom  𝐹  ∪  { ∅ } ) ) | 
						
							| 48 | 46 47 | syl6 | ⊢ ( ∪  ◡ { 𝑦 }  ∈  dom  𝐹  →  ( 𝑦  ∈  ( V  ×  V )  →  𝑦  ∈  ( ◡ dom  𝐹  ∪  { ∅ } ) ) ) | 
						
							| 49 | 31 48 | syl | ⊢ ( ( ( 𝑦  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ∧  𝑤  =  ∪  ◡ { 𝑦 } )  ∧  𝑤 𝐹 𝑧 )  →  ( 𝑦  ∈  ( V  ×  V )  →  𝑦  ∈  ( ◡ dom  𝐹  ∪  { ∅ } ) ) ) | 
						
							| 50 |  | elun2 | ⊢ ( 𝑦  ∈  { ∅ }  →  𝑦  ∈  ( ◡ dom  𝐹  ∪  { ∅ } ) ) | 
						
							| 51 | 50 | a1i | ⊢ ( ( ( 𝑦  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ∧  𝑤  =  ∪  ◡ { 𝑦 } )  ∧  𝑤 𝐹 𝑧 )  →  ( 𝑦  ∈  { ∅ }  →  𝑦  ∈  ( ◡ dom  𝐹  ∪  { ∅ } ) ) ) | 
						
							| 52 |  | simpll | ⊢ ( ( ( 𝑦  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ∧  𝑤  =  ∪  ◡ { 𝑦 } )  ∧  𝑤 𝐹 𝑧 )  →  𝑦  ∈  ( ( V  ×  V )  ∪  { ∅ } ) ) | 
						
							| 53 |  | elun | ⊢ ( 𝑦  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ↔  ( 𝑦  ∈  ( V  ×  V )  ∨  𝑦  ∈  { ∅ } ) ) | 
						
							| 54 | 52 53 | sylib | ⊢ ( ( ( 𝑦  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ∧  𝑤  =  ∪  ◡ { 𝑦 } )  ∧  𝑤 𝐹 𝑧 )  →  ( 𝑦  ∈  ( V  ×  V )  ∨  𝑦  ∈  { ∅ } ) ) | 
						
							| 55 | 49 51 54 | mpjaod | ⊢ ( ( ( 𝑦  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ∧  𝑤  =  ∪  ◡ { 𝑦 } )  ∧  𝑤 𝐹 𝑧 )  →  𝑦  ∈  ( ◡ dom  𝐹  ∪  { ∅ } ) ) | 
						
							| 56 |  | simpr | ⊢ ( ( ( 𝑦  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ∧  𝑤  =  ∪  ◡ { 𝑦 } )  ∧  𝑤 𝐹 𝑧 )  →  𝑤 𝐹 𝑧 ) | 
						
							| 57 | 28 56 | eqbrtrrd | ⊢ ( ( ( 𝑦  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ∧  𝑤  =  ∪  ◡ { 𝑦 } )  ∧  𝑤 𝐹 𝑧 )  →  ∪  ◡ { 𝑦 } 𝐹 𝑧 ) | 
						
							| 58 | 55 57 | jca | ⊢ ( ( ( 𝑦  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ∧  𝑤  =  ∪  ◡ { 𝑦 } )  ∧  𝑤 𝐹 𝑧 )  →  ( 𝑦  ∈  ( ◡ dom  𝐹  ∪  { ∅ } )  ∧  ∪  ◡ { 𝑦 } 𝐹 𝑧 ) ) | 
						
							| 59 | 27 58 | sylanb | ⊢ ( ( 𝑦 ( 𝑥  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ↦  ∪  ◡ { 𝑥 } ) 𝑤  ∧  𝑤 𝐹 𝑧 )  →  ( 𝑦  ∈  ( ◡ dom  𝐹  ∪  { ∅ } )  ∧  ∪  ◡ { 𝑦 } 𝐹 𝑧 ) ) | 
						
							| 60 |  | brtpos2 | ⊢ ( 𝑧  ∈  V  →  ( 𝑦 tpos  𝐹 𝑧  ↔  ( 𝑦  ∈  ( ◡ dom  𝐹  ∪  { ∅ } )  ∧  ∪  ◡ { 𝑦 } 𝐹 𝑧 ) ) ) | 
						
							| 61 | 15 60 | ax-mp | ⊢ ( 𝑦 tpos  𝐹 𝑧  ↔  ( 𝑦  ∈  ( ◡ dom  𝐹  ∪  { ∅ } )  ∧  ∪  ◡ { 𝑦 } 𝐹 𝑧 ) ) | 
						
							| 62 | 59 61 | sylibr | ⊢ ( ( 𝑦 ( 𝑥  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ↦  ∪  ◡ { 𝑥 } ) 𝑤  ∧  𝑤 𝐹 𝑧 )  →  𝑦 tpos  𝐹 𝑧 ) | 
						
							| 63 |  | df-br | ⊢ ( 𝑦 tpos  𝐹 𝑧  ↔  〈 𝑦 ,  𝑧 〉  ∈  tpos  𝐹 ) | 
						
							| 64 | 62 63 | sylib | ⊢ ( ( 𝑦 ( 𝑥  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ↦  ∪  ◡ { 𝑥 } ) 𝑤  ∧  𝑤 𝐹 𝑧 )  →  〈 𝑦 ,  𝑧 〉  ∈  tpos  𝐹 ) | 
						
							| 65 | 64 | exlimiv | ⊢ ( ∃ 𝑤 ( 𝑦 ( 𝑥  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ↦  ∪  ◡ { 𝑥 } ) 𝑤  ∧  𝑤 𝐹 𝑧 )  →  〈 𝑦 ,  𝑧 〉  ∈  tpos  𝐹 ) | 
						
							| 66 | 16 65 | sylbi | ⊢ ( 〈 𝑦 ,  𝑧 〉  ∈  ( 𝐹  ∘  ( 𝑥  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ↦  ∪  ◡ { 𝑥 } ) )  →  〈 𝑦 ,  𝑧 〉  ∈  tpos  𝐹 ) | 
						
							| 67 | 13 66 | relssi | ⊢ ( 𝐹  ∘  ( 𝑥  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ↦  ∪  ◡ { 𝑥 } ) )  ⊆  tpos  𝐹 | 
						
							| 68 | 12 67 | eqssi | ⊢ tpos  𝐹  =  ( 𝐹  ∘  ( 𝑥  ∈  ( ( V  ×  V )  ∪  { ∅ } )  ↦  ∪  ◡ { 𝑥 } ) ) |