| Step | Hyp | Ref | Expression | 
						
							| 1 |  | dfac8clem.1 | ⊢ 𝐹  =  ( 𝑠  ∈  ( 𝐴  ∖  { ∅ } )  ↦  ( ℩ 𝑎  ∈  𝑠 ∀ 𝑏  ∈  𝑠 ¬  𝑏 𝑟 𝑎 ) ) | 
						
							| 2 |  | eldifsn | ⊢ ( 𝑠  ∈  ( 𝐴  ∖  { ∅ } )  ↔  ( 𝑠  ∈  𝐴  ∧  𝑠  ≠  ∅ ) ) | 
						
							| 3 |  | elssuni | ⊢ ( 𝑠  ∈  𝐴  →  𝑠  ⊆  ∪  𝐴 ) | 
						
							| 4 | 3 | ad2antrl | ⊢ ( ( ( 𝐴  ∈  𝐵  ∧  𝑟  We  ∪  𝐴 )  ∧  ( 𝑠  ∈  𝐴  ∧  𝑠  ≠  ∅ ) )  →  𝑠  ⊆  ∪  𝐴 ) | 
						
							| 5 |  | simplr | ⊢ ( ( ( 𝐴  ∈  𝐵  ∧  𝑟  We  ∪  𝐴 )  ∧  ( 𝑠  ∈  𝐴  ∧  𝑠  ≠  ∅ ) )  →  𝑟  We  ∪  𝐴 ) | 
						
							| 6 |  | vex | ⊢ 𝑟  ∈  V | 
						
							| 7 |  | exse2 | ⊢ ( 𝑟  ∈  V  →  𝑟  Se  ∪  𝐴 ) | 
						
							| 8 | 6 7 | mp1i | ⊢ ( ( ( 𝐴  ∈  𝐵  ∧  𝑟  We  ∪  𝐴 )  ∧  ( 𝑠  ∈  𝐴  ∧  𝑠  ≠  ∅ ) )  →  𝑟  Se  ∪  𝐴 ) | 
						
							| 9 |  | simprr | ⊢ ( ( ( 𝐴  ∈  𝐵  ∧  𝑟  We  ∪  𝐴 )  ∧  ( 𝑠  ∈  𝐴  ∧  𝑠  ≠  ∅ ) )  →  𝑠  ≠  ∅ ) | 
						
							| 10 |  | wereu2 | ⊢ ( ( ( 𝑟  We  ∪  𝐴  ∧  𝑟  Se  ∪  𝐴 )  ∧  ( 𝑠  ⊆  ∪  𝐴  ∧  𝑠  ≠  ∅ ) )  →  ∃! 𝑎  ∈  𝑠 ∀ 𝑏  ∈  𝑠 ¬  𝑏 𝑟 𝑎 ) | 
						
							| 11 | 5 8 4 9 10 | syl22anc | ⊢ ( ( ( 𝐴  ∈  𝐵  ∧  𝑟  We  ∪  𝐴 )  ∧  ( 𝑠  ∈  𝐴  ∧  𝑠  ≠  ∅ ) )  →  ∃! 𝑎  ∈  𝑠 ∀ 𝑏  ∈  𝑠 ¬  𝑏 𝑟 𝑎 ) | 
						
							| 12 |  | riotacl | ⊢ ( ∃! 𝑎  ∈  𝑠 ∀ 𝑏  ∈  𝑠 ¬  𝑏 𝑟 𝑎  →  ( ℩ 𝑎  ∈  𝑠 ∀ 𝑏  ∈  𝑠 ¬  𝑏 𝑟 𝑎 )  ∈  𝑠 ) | 
						
							| 13 | 11 12 | syl | ⊢ ( ( ( 𝐴  ∈  𝐵  ∧  𝑟  We  ∪  𝐴 )  ∧  ( 𝑠  ∈  𝐴  ∧  𝑠  ≠  ∅ ) )  →  ( ℩ 𝑎  ∈  𝑠 ∀ 𝑏  ∈  𝑠 ¬  𝑏 𝑟 𝑎 )  ∈  𝑠 ) | 
						
							| 14 | 4 13 | sseldd | ⊢ ( ( ( 𝐴  ∈  𝐵  ∧  𝑟  We  ∪  𝐴 )  ∧  ( 𝑠  ∈  𝐴  ∧  𝑠  ≠  ∅ ) )  →  ( ℩ 𝑎  ∈  𝑠 ∀ 𝑏  ∈  𝑠 ¬  𝑏 𝑟 𝑎 )  ∈  ∪  𝐴 ) | 
						
							| 15 | 2 14 | sylan2b | ⊢ ( ( ( 𝐴  ∈  𝐵  ∧  𝑟  We  ∪  𝐴 )  ∧  𝑠  ∈  ( 𝐴  ∖  { ∅ } ) )  →  ( ℩ 𝑎  ∈  𝑠 ∀ 𝑏  ∈  𝑠 ¬  𝑏 𝑟 𝑎 )  ∈  ∪  𝐴 ) | 
						
							| 16 | 15 1 | fmptd | ⊢ ( ( 𝐴  ∈  𝐵  ∧  𝑟  We  ∪  𝐴 )  →  𝐹 : ( 𝐴  ∖  { ∅ } ) ⟶ ∪  𝐴 ) | 
						
							| 17 |  | difexg | ⊢ ( 𝐴  ∈  𝐵  →  ( 𝐴  ∖  { ∅ } )  ∈  V ) | 
						
							| 18 | 17 | adantr | ⊢ ( ( 𝐴  ∈  𝐵  ∧  𝑟  We  ∪  𝐴 )  →  ( 𝐴  ∖  { ∅ } )  ∈  V ) | 
						
							| 19 |  | uniexg | ⊢ ( 𝐴  ∈  𝐵  →  ∪  𝐴  ∈  V ) | 
						
							| 20 | 19 | adantr | ⊢ ( ( 𝐴  ∈  𝐵  ∧  𝑟  We  ∪  𝐴 )  →  ∪  𝐴  ∈  V ) | 
						
							| 21 |  | fex2 | ⊢ ( ( 𝐹 : ( 𝐴  ∖  { ∅ } ) ⟶ ∪  𝐴  ∧  ( 𝐴  ∖  { ∅ } )  ∈  V  ∧  ∪  𝐴  ∈  V )  →  𝐹  ∈  V ) | 
						
							| 22 | 16 18 20 21 | syl3anc | ⊢ ( ( 𝐴  ∈  𝐵  ∧  𝑟  We  ∪  𝐴 )  →  𝐹  ∈  V ) | 
						
							| 23 |  | riotaex | ⊢ ( ℩ 𝑎  ∈  𝑠 ∀ 𝑏  ∈  𝑠 ¬  𝑏 𝑟 𝑎 )  ∈  V | 
						
							| 24 | 1 | fvmpt2 | ⊢ ( ( 𝑠  ∈  ( 𝐴  ∖  { ∅ } )  ∧  ( ℩ 𝑎  ∈  𝑠 ∀ 𝑏  ∈  𝑠 ¬  𝑏 𝑟 𝑎 )  ∈  V )  →  ( 𝐹 ‘ 𝑠 )  =  ( ℩ 𝑎  ∈  𝑠 ∀ 𝑏  ∈  𝑠 ¬  𝑏 𝑟 𝑎 ) ) | 
						
							| 25 | 23 24 | mpan2 | ⊢ ( 𝑠  ∈  ( 𝐴  ∖  { ∅ } )  →  ( 𝐹 ‘ 𝑠 )  =  ( ℩ 𝑎  ∈  𝑠 ∀ 𝑏  ∈  𝑠 ¬  𝑏 𝑟 𝑎 ) ) | 
						
							| 26 | 2 25 | sylbir | ⊢ ( ( 𝑠  ∈  𝐴  ∧  𝑠  ≠  ∅ )  →  ( 𝐹 ‘ 𝑠 )  =  ( ℩ 𝑎  ∈  𝑠 ∀ 𝑏  ∈  𝑠 ¬  𝑏 𝑟 𝑎 ) ) | 
						
							| 27 | 26 | adantl | ⊢ ( ( ( 𝐴  ∈  𝐵  ∧  𝑟  We  ∪  𝐴 )  ∧  ( 𝑠  ∈  𝐴  ∧  𝑠  ≠  ∅ ) )  →  ( 𝐹 ‘ 𝑠 )  =  ( ℩ 𝑎  ∈  𝑠 ∀ 𝑏  ∈  𝑠 ¬  𝑏 𝑟 𝑎 ) ) | 
						
							| 28 | 27 13 | eqeltrd | ⊢ ( ( ( 𝐴  ∈  𝐵  ∧  𝑟  We  ∪  𝐴 )  ∧  ( 𝑠  ∈  𝐴  ∧  𝑠  ≠  ∅ ) )  →  ( 𝐹 ‘ 𝑠 )  ∈  𝑠 ) | 
						
							| 29 | 28 | expr | ⊢ ( ( ( 𝐴  ∈  𝐵  ∧  𝑟  We  ∪  𝐴 )  ∧  𝑠  ∈  𝐴 )  →  ( 𝑠  ≠  ∅  →  ( 𝐹 ‘ 𝑠 )  ∈  𝑠 ) ) | 
						
							| 30 | 29 | ralrimiva | ⊢ ( ( 𝐴  ∈  𝐵  ∧  𝑟  We  ∪  𝐴 )  →  ∀ 𝑠  ∈  𝐴 ( 𝑠  ≠  ∅  →  ( 𝐹 ‘ 𝑠 )  ∈  𝑠 ) ) | 
						
							| 31 |  | nfv | ⊢ Ⅎ 𝑠 𝑧  ≠  ∅ | 
						
							| 32 |  | nfmpt1 | ⊢ Ⅎ 𝑠 ( 𝑠  ∈  ( 𝐴  ∖  { ∅ } )  ↦  ( ℩ 𝑎  ∈  𝑠 ∀ 𝑏  ∈  𝑠 ¬  𝑏 𝑟 𝑎 ) ) | 
						
							| 33 | 1 32 | nfcxfr | ⊢ Ⅎ 𝑠 𝐹 | 
						
							| 34 |  | nfcv | ⊢ Ⅎ 𝑠 𝑧 | 
						
							| 35 | 33 34 | nffv | ⊢ Ⅎ 𝑠 ( 𝐹 ‘ 𝑧 ) | 
						
							| 36 | 35 | nfel1 | ⊢ Ⅎ 𝑠 ( 𝐹 ‘ 𝑧 )  ∈  𝑧 | 
						
							| 37 | 31 36 | nfim | ⊢ Ⅎ 𝑠 ( 𝑧  ≠  ∅  →  ( 𝐹 ‘ 𝑧 )  ∈  𝑧 ) | 
						
							| 38 |  | nfv | ⊢ Ⅎ 𝑧 ( 𝑠  ≠  ∅  →  ( 𝐹 ‘ 𝑠 )  ∈  𝑠 ) | 
						
							| 39 |  | neeq1 | ⊢ ( 𝑧  =  𝑠  →  ( 𝑧  ≠  ∅  ↔  𝑠  ≠  ∅ ) ) | 
						
							| 40 |  | fveq2 | ⊢ ( 𝑧  =  𝑠  →  ( 𝐹 ‘ 𝑧 )  =  ( 𝐹 ‘ 𝑠 ) ) | 
						
							| 41 |  | id | ⊢ ( 𝑧  =  𝑠  →  𝑧  =  𝑠 ) | 
						
							| 42 | 40 41 | eleq12d | ⊢ ( 𝑧  =  𝑠  →  ( ( 𝐹 ‘ 𝑧 )  ∈  𝑧  ↔  ( 𝐹 ‘ 𝑠 )  ∈  𝑠 ) ) | 
						
							| 43 | 39 42 | imbi12d | ⊢ ( 𝑧  =  𝑠  →  ( ( 𝑧  ≠  ∅  →  ( 𝐹 ‘ 𝑧 )  ∈  𝑧 )  ↔  ( 𝑠  ≠  ∅  →  ( 𝐹 ‘ 𝑠 )  ∈  𝑠 ) ) ) | 
						
							| 44 | 37 38 43 | cbvralw | ⊢ ( ∀ 𝑧  ∈  𝐴 ( 𝑧  ≠  ∅  →  ( 𝐹 ‘ 𝑧 )  ∈  𝑧 )  ↔  ∀ 𝑠  ∈  𝐴 ( 𝑠  ≠  ∅  →  ( 𝐹 ‘ 𝑠 )  ∈  𝑠 ) ) | 
						
							| 45 | 30 44 | sylibr | ⊢ ( ( 𝐴  ∈  𝐵  ∧  𝑟  We  ∪  𝐴 )  →  ∀ 𝑧  ∈  𝐴 ( 𝑧  ≠  ∅  →  ( 𝐹 ‘ 𝑧 )  ∈  𝑧 ) ) | 
						
							| 46 |  | fveq1 | ⊢ ( 𝑓  =  𝐹  →  ( 𝑓 ‘ 𝑧 )  =  ( 𝐹 ‘ 𝑧 ) ) | 
						
							| 47 | 46 | eleq1d | ⊢ ( 𝑓  =  𝐹  →  ( ( 𝑓 ‘ 𝑧 )  ∈  𝑧  ↔  ( 𝐹 ‘ 𝑧 )  ∈  𝑧 ) ) | 
						
							| 48 | 47 | imbi2d | ⊢ ( 𝑓  =  𝐹  →  ( ( 𝑧  ≠  ∅  →  ( 𝑓 ‘ 𝑧 )  ∈  𝑧 )  ↔  ( 𝑧  ≠  ∅  →  ( 𝐹 ‘ 𝑧 )  ∈  𝑧 ) ) ) | 
						
							| 49 | 48 | ralbidv | ⊢ ( 𝑓  =  𝐹  →  ( ∀ 𝑧  ∈  𝐴 ( 𝑧  ≠  ∅  →  ( 𝑓 ‘ 𝑧 )  ∈  𝑧 )  ↔  ∀ 𝑧  ∈  𝐴 ( 𝑧  ≠  ∅  →  ( 𝐹 ‘ 𝑧 )  ∈  𝑧 ) ) ) | 
						
							| 50 | 22 45 49 | spcedv | ⊢ ( ( 𝐴  ∈  𝐵  ∧  𝑟  We  ∪  𝐴 )  →  ∃ 𝑓 ∀ 𝑧  ∈  𝐴 ( 𝑧  ≠  ∅  →  ( 𝑓 ‘ 𝑧 )  ∈  𝑧 ) ) | 
						
							| 51 | 50 | ex | ⊢ ( 𝐴  ∈  𝐵  →  ( 𝑟  We  ∪  𝐴  →  ∃ 𝑓 ∀ 𝑧  ∈  𝐴 ( 𝑧  ≠  ∅  →  ( 𝑓 ‘ 𝑧 )  ∈  𝑧 ) ) ) | 
						
							| 52 | 51 | exlimdv | ⊢ ( 𝐴  ∈  𝐵  →  ( ∃ 𝑟 𝑟  We  ∪  𝐴  →  ∃ 𝑓 ∀ 𝑧  ∈  𝐴 ( 𝑧  ≠  ∅  →  ( 𝑓 ‘ 𝑧 )  ∈  𝑧 ) ) ) |