| Step | Hyp | Ref | Expression | 
						
							| 1 |  | snprc | ⊢ ( ¬  𝐴  ∈  V  ↔  { 𝐴 }  =  ∅ ) | 
						
							| 2 |  | fr0 | ⊢ 𝑅  Fr  ∅ | 
						
							| 3 |  | freq2 | ⊢ ( { 𝐴 }  =  ∅  →  ( 𝑅  Fr  { 𝐴 }  ↔  𝑅  Fr  ∅ ) ) | 
						
							| 4 | 2 3 | mpbiri | ⊢ ( { 𝐴 }  =  ∅  →  𝑅  Fr  { 𝐴 } ) | 
						
							| 5 | 1 4 | sylbi | ⊢ ( ¬  𝐴  ∈  V  →  𝑅  Fr  { 𝐴 } ) | 
						
							| 6 | 5 | adantl | ⊢ ( ( Rel  𝑅  ∧  ¬  𝐴  ∈  V )  →  𝑅  Fr  { 𝐴 } ) | 
						
							| 7 |  | brrelex1 | ⊢ ( ( Rel  𝑅  ∧  𝐴 𝑅 𝐴 )  →  𝐴  ∈  V ) | 
						
							| 8 | 7 | stoic1a | ⊢ ( ( Rel  𝑅  ∧  ¬  𝐴  ∈  V )  →  ¬  𝐴 𝑅 𝐴 ) | 
						
							| 9 | 6 8 | 2thd | ⊢ ( ( Rel  𝑅  ∧  ¬  𝐴  ∈  V )  →  ( 𝑅  Fr  { 𝐴 }  ↔  ¬  𝐴 𝑅 𝐴 ) ) | 
						
							| 10 | 9 | ex | ⊢ ( Rel  𝑅  →  ( ¬  𝐴  ∈  V  →  ( 𝑅  Fr  { 𝐴 }  ↔  ¬  𝐴 𝑅 𝐴 ) ) ) | 
						
							| 11 |  | df-fr | ⊢ ( 𝑅  Fr  { 𝐴 }  ↔  ∀ 𝑥 ( ( 𝑥  ⊆  { 𝐴 }  ∧  𝑥  ≠  ∅ )  →  ∃ 𝑦  ∈  𝑥 ∀ 𝑧  ∈  𝑥 ¬  𝑧 𝑅 𝑦 ) ) | 
						
							| 12 |  | sssn | ⊢ ( 𝑥  ⊆  { 𝐴 }  ↔  ( 𝑥  =  ∅  ∨  𝑥  =  { 𝐴 } ) ) | 
						
							| 13 |  | neor | ⊢ ( ( 𝑥  =  ∅  ∨  𝑥  =  { 𝐴 } )  ↔  ( 𝑥  ≠  ∅  →  𝑥  =  { 𝐴 } ) ) | 
						
							| 14 | 12 13 | sylbb | ⊢ ( 𝑥  ⊆  { 𝐴 }  →  ( 𝑥  ≠  ∅  →  𝑥  =  { 𝐴 } ) ) | 
						
							| 15 | 14 | imp | ⊢ ( ( 𝑥  ⊆  { 𝐴 }  ∧  𝑥  ≠  ∅ )  →  𝑥  =  { 𝐴 } ) | 
						
							| 16 | 15 | adantl | ⊢ ( ( 𝐴  ∈  V  ∧  ( 𝑥  ⊆  { 𝐴 }  ∧  𝑥  ≠  ∅ ) )  →  𝑥  =  { 𝐴 } ) | 
						
							| 17 |  | eqimss | ⊢ ( 𝑥  =  { 𝐴 }  →  𝑥  ⊆  { 𝐴 } ) | 
						
							| 18 | 17 | adantl | ⊢ ( ( 𝐴  ∈  V  ∧  𝑥  =  { 𝐴 } )  →  𝑥  ⊆  { 𝐴 } ) | 
						
							| 19 |  | snnzg | ⊢ ( 𝐴  ∈  V  →  { 𝐴 }  ≠  ∅ ) | 
						
							| 20 |  | neeq1 | ⊢ ( 𝑥  =  { 𝐴 }  →  ( 𝑥  ≠  ∅  ↔  { 𝐴 }  ≠  ∅ ) ) | 
						
							| 21 | 19 20 | syl5ibrcom | ⊢ ( 𝐴  ∈  V  →  ( 𝑥  =  { 𝐴 }  →  𝑥  ≠  ∅ ) ) | 
						
							| 22 | 21 | imp | ⊢ ( ( 𝐴  ∈  V  ∧  𝑥  =  { 𝐴 } )  →  𝑥  ≠  ∅ ) | 
						
							| 23 | 18 22 | jca | ⊢ ( ( 𝐴  ∈  V  ∧  𝑥  =  { 𝐴 } )  →  ( 𝑥  ⊆  { 𝐴 }  ∧  𝑥  ≠  ∅ ) ) | 
						
							| 24 | 16 23 | impbida | ⊢ ( 𝐴  ∈  V  →  ( ( 𝑥  ⊆  { 𝐴 }  ∧  𝑥  ≠  ∅ )  ↔  𝑥  =  { 𝐴 } ) ) | 
						
							| 25 | 24 | imbi1d | ⊢ ( 𝐴  ∈  V  →  ( ( ( 𝑥  ⊆  { 𝐴 }  ∧  𝑥  ≠  ∅ )  →  ∃ 𝑦  ∈  𝑥 ∀ 𝑧  ∈  𝑥 ¬  𝑧 𝑅 𝑦 )  ↔  ( 𝑥  =  { 𝐴 }  →  ∃ 𝑦  ∈  𝑥 ∀ 𝑧  ∈  𝑥 ¬  𝑧 𝑅 𝑦 ) ) ) | 
						
							| 26 | 25 | albidv | ⊢ ( 𝐴  ∈  V  →  ( ∀ 𝑥 ( ( 𝑥  ⊆  { 𝐴 }  ∧  𝑥  ≠  ∅ )  →  ∃ 𝑦  ∈  𝑥 ∀ 𝑧  ∈  𝑥 ¬  𝑧 𝑅 𝑦 )  ↔  ∀ 𝑥 ( 𝑥  =  { 𝐴 }  →  ∃ 𝑦  ∈  𝑥 ∀ 𝑧  ∈  𝑥 ¬  𝑧 𝑅 𝑦 ) ) ) | 
						
							| 27 |  | snex | ⊢ { 𝐴 }  ∈  V | 
						
							| 28 |  | raleq | ⊢ ( 𝑥  =  { 𝐴 }  →  ( ∀ 𝑧  ∈  𝑥 ¬  𝑧 𝑅 𝑦  ↔  ∀ 𝑧  ∈  { 𝐴 } ¬  𝑧 𝑅 𝑦 ) ) | 
						
							| 29 | 28 | rexeqbi1dv | ⊢ ( 𝑥  =  { 𝐴 }  →  ( ∃ 𝑦  ∈  𝑥 ∀ 𝑧  ∈  𝑥 ¬  𝑧 𝑅 𝑦  ↔  ∃ 𝑦  ∈  { 𝐴 } ∀ 𝑧  ∈  { 𝐴 } ¬  𝑧 𝑅 𝑦 ) ) | 
						
							| 30 | 27 29 | ceqsalv | ⊢ ( ∀ 𝑥 ( 𝑥  =  { 𝐴 }  →  ∃ 𝑦  ∈  𝑥 ∀ 𝑧  ∈  𝑥 ¬  𝑧 𝑅 𝑦 )  ↔  ∃ 𝑦  ∈  { 𝐴 } ∀ 𝑧  ∈  { 𝐴 } ¬  𝑧 𝑅 𝑦 ) | 
						
							| 31 | 26 30 | bitrdi | ⊢ ( 𝐴  ∈  V  →  ( ∀ 𝑥 ( ( 𝑥  ⊆  { 𝐴 }  ∧  𝑥  ≠  ∅ )  →  ∃ 𝑦  ∈  𝑥 ∀ 𝑧  ∈  𝑥 ¬  𝑧 𝑅 𝑦 )  ↔  ∃ 𝑦  ∈  { 𝐴 } ∀ 𝑧  ∈  { 𝐴 } ¬  𝑧 𝑅 𝑦 ) ) | 
						
							| 32 | 11 31 | bitrid | ⊢ ( 𝐴  ∈  V  →  ( 𝑅  Fr  { 𝐴 }  ↔  ∃ 𝑦  ∈  { 𝐴 } ∀ 𝑧  ∈  { 𝐴 } ¬  𝑧 𝑅 𝑦 ) ) | 
						
							| 33 |  | breq2 | ⊢ ( 𝑦  =  𝐴  →  ( 𝑧 𝑅 𝑦  ↔  𝑧 𝑅 𝐴 ) ) | 
						
							| 34 | 33 | notbid | ⊢ ( 𝑦  =  𝐴  →  ( ¬  𝑧 𝑅 𝑦  ↔  ¬  𝑧 𝑅 𝐴 ) ) | 
						
							| 35 | 34 | ralbidv | ⊢ ( 𝑦  =  𝐴  →  ( ∀ 𝑧  ∈  { 𝐴 } ¬  𝑧 𝑅 𝑦  ↔  ∀ 𝑧  ∈  { 𝐴 } ¬  𝑧 𝑅 𝐴 ) ) | 
						
							| 36 | 35 | rexsng | ⊢ ( 𝐴  ∈  V  →  ( ∃ 𝑦  ∈  { 𝐴 } ∀ 𝑧  ∈  { 𝐴 } ¬  𝑧 𝑅 𝑦  ↔  ∀ 𝑧  ∈  { 𝐴 } ¬  𝑧 𝑅 𝐴 ) ) | 
						
							| 37 |  | breq1 | ⊢ ( 𝑧  =  𝐴  →  ( 𝑧 𝑅 𝐴  ↔  𝐴 𝑅 𝐴 ) ) | 
						
							| 38 | 37 | notbid | ⊢ ( 𝑧  =  𝐴  →  ( ¬  𝑧 𝑅 𝐴  ↔  ¬  𝐴 𝑅 𝐴 ) ) | 
						
							| 39 | 38 | ralsng | ⊢ ( 𝐴  ∈  V  →  ( ∀ 𝑧  ∈  { 𝐴 } ¬  𝑧 𝑅 𝐴  ↔  ¬  𝐴 𝑅 𝐴 ) ) | 
						
							| 40 | 32 36 39 | 3bitrd | ⊢ ( 𝐴  ∈  V  →  ( 𝑅  Fr  { 𝐴 }  ↔  ¬  𝐴 𝑅 𝐴 ) ) | 
						
							| 41 | 10 40 | pm2.61d2 | ⊢ ( Rel  𝑅  →  ( 𝑅  Fr  { 𝐴 }  ↔  ¬  𝐴 𝑅 𝐴 ) ) |