| Step | Hyp | Ref | Expression | 
						
							| 1 |  | prproropf1o.o | ⊢ 𝑂  =  ( 𝑅  ∩  ( 𝑉  ×  𝑉 ) ) | 
						
							| 2 |  | prproropf1o.p | ⊢ 𝑃  =  { 𝑝  ∈  𝒫  𝑉  ∣  ( ♯ ‘ 𝑝 )  =  2 } | 
						
							| 3 |  | prproropf1o.f | ⊢ 𝐹  =  ( 𝑝  ∈  𝑃  ↦  〈 inf ( 𝑝 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑝 ,  𝑉 ,  𝑅 ) 〉 ) | 
						
							| 4 |  | infeq1 | ⊢ ( 𝑝  =  𝑍  →  inf ( 𝑝 ,  𝑉 ,  𝑅 )  =  inf ( 𝑍 ,  𝑉 ,  𝑅 ) ) | 
						
							| 5 |  | supeq1 | ⊢ ( 𝑝  =  𝑍  →  sup ( 𝑝 ,  𝑉 ,  𝑅 )  =  sup ( 𝑍 ,  𝑉 ,  𝑅 ) ) | 
						
							| 6 | 4 5 | opeq12d | ⊢ ( 𝑝  =  𝑍  →  〈 inf ( 𝑝 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑝 ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( 𝑍 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑍 ,  𝑉 ,  𝑅 ) 〉 ) | 
						
							| 7 |  | simp3 | ⊢ ( ( 𝑅  Or  𝑉  ∧  𝑊  ∈  𝑃  ∧  𝑍  ∈  𝑃 )  →  𝑍  ∈  𝑃 ) | 
						
							| 8 |  | opex | ⊢ 〈 inf ( 𝑍 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑍 ,  𝑉 ,  𝑅 ) 〉  ∈  V | 
						
							| 9 | 8 | a1i | ⊢ ( ( 𝑅  Or  𝑉  ∧  𝑊  ∈  𝑃  ∧  𝑍  ∈  𝑃 )  →  〈 inf ( 𝑍 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑍 ,  𝑉 ,  𝑅 ) 〉  ∈  V ) | 
						
							| 10 | 3 6 7 9 | fvmptd3 | ⊢ ( ( 𝑅  Or  𝑉  ∧  𝑊  ∈  𝑃  ∧  𝑍  ∈  𝑃 )  →  ( 𝐹 ‘ 𝑍 )  =  〈 inf ( 𝑍 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑍 ,  𝑉 ,  𝑅 ) 〉 ) | 
						
							| 11 |  | infeq1 | ⊢ ( 𝑝  =  𝑊  →  inf ( 𝑝 ,  𝑉 ,  𝑅 )  =  inf ( 𝑊 ,  𝑉 ,  𝑅 ) ) | 
						
							| 12 |  | supeq1 | ⊢ ( 𝑝  =  𝑊  →  sup ( 𝑝 ,  𝑉 ,  𝑅 )  =  sup ( 𝑊 ,  𝑉 ,  𝑅 ) ) | 
						
							| 13 | 11 12 | opeq12d | ⊢ ( 𝑝  =  𝑊  →  〈 inf ( 𝑝 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑝 ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( 𝑊 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑊 ,  𝑉 ,  𝑅 ) 〉 ) | 
						
							| 14 |  | simp2 | ⊢ ( ( 𝑅  Or  𝑉  ∧  𝑊  ∈  𝑃  ∧  𝑍  ∈  𝑃 )  →  𝑊  ∈  𝑃 ) | 
						
							| 15 |  | opex | ⊢ 〈 inf ( 𝑊 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑊 ,  𝑉 ,  𝑅 ) 〉  ∈  V | 
						
							| 16 | 15 | a1i | ⊢ ( ( 𝑅  Or  𝑉  ∧  𝑊  ∈  𝑃  ∧  𝑍  ∈  𝑃 )  →  〈 inf ( 𝑊 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑊 ,  𝑉 ,  𝑅 ) 〉  ∈  V ) | 
						
							| 17 | 3 13 14 16 | fvmptd3 | ⊢ ( ( 𝑅  Or  𝑉  ∧  𝑊  ∈  𝑃  ∧  𝑍  ∈  𝑃 )  →  ( 𝐹 ‘ 𝑊 )  =  〈 inf ( 𝑊 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑊 ,  𝑉 ,  𝑅 ) 〉 ) | 
						
							| 18 | 10 17 | eqeq12d | ⊢ ( ( 𝑅  Or  𝑉  ∧  𝑊  ∈  𝑃  ∧  𝑍  ∈  𝑃 )  →  ( ( 𝐹 ‘ 𝑍 )  =  ( 𝐹 ‘ 𝑊 )  ↔  〈 inf ( 𝑍 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑍 ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( 𝑊 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑊 ,  𝑉 ,  𝑅 ) 〉 ) ) | 
						
							| 19 | 2 | prpair | ⊢ ( 𝑍  ∈  𝑃  ↔  ∃ 𝑐  ∈  𝑉 ∃ 𝑑  ∈  𝑉 ( 𝑍  =  { 𝑐 ,  𝑑 }  ∧  𝑐  ≠  𝑑 ) ) | 
						
							| 20 | 2 | prpair | ⊢ ( 𝑊  ∈  𝑃  ↔  ∃ 𝑎  ∈  𝑉 ∃ 𝑏  ∈  𝑉 ( 𝑊  =  { 𝑎 ,  𝑏 }  ∧  𝑎  ≠  𝑏 ) ) | 
						
							| 21 |  | id | ⊢ ( 𝑅  Or  𝑉  →  𝑅  Or  𝑉 ) | 
						
							| 22 | 21 | infexd | ⊢ ( 𝑅  Or  𝑉  →  inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  ∈  V ) | 
						
							| 23 | 21 | supexd | ⊢ ( 𝑅  Or  𝑉  →  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  ∈  V ) | 
						
							| 24 | 22 23 | jca | ⊢ ( 𝑅  Or  𝑉  →  ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  ∈  V  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  ∈  V ) ) | 
						
							| 25 | 24 | ad4antr | ⊢ ( ( ( ( ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  ∧  ( 𝑊  =  { 𝑎 ,  𝑏 }  ∧  𝑎  ≠  𝑏 ) )  ∧  ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 ) )  ∧  ( 𝑍  =  { 𝑐 ,  𝑑 }  ∧  𝑐  ≠  𝑑 ) )  →  ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  ∈  V  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  ∈  V ) ) | 
						
							| 26 |  | opthg | ⊢ ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  ∈  V  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  ∈  V )  →  ( 〈 inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 ) ,  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) ,  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) 〉  ↔  ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) ) ) ) | 
						
							| 27 | 25 26 | syl | ⊢ ( ( ( ( ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  ∧  ( 𝑊  =  { 𝑎 ,  𝑏 }  ∧  𝑎  ≠  𝑏 ) )  ∧  ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 ) )  ∧  ( 𝑍  =  { 𝑐 ,  𝑑 }  ∧  𝑐  ≠  𝑑 ) )  →  ( 〈 inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 ) ,  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) ,  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) 〉  ↔  ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) ) ) ) | 
						
							| 28 |  | solin | ⊢ ( ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  →  ( 𝑎 𝑅 𝑏  ∨  𝑎  =  𝑏  ∨  𝑏 𝑅 𝑎 ) ) | 
						
							| 29 |  | infpr | ⊢ ( ( 𝑅  Or  𝑉  ∧  𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 )  →  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  =  if ( 𝑎 𝑅 𝑏 ,  𝑎 ,  𝑏 ) ) | 
						
							| 30 | 29 | 3expb | ⊢ ( ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  →  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  =  if ( 𝑎 𝑅 𝑏 ,  𝑎 ,  𝑏 ) ) | 
						
							| 31 |  | iftrue | ⊢ ( 𝑎 𝑅 𝑏  →  if ( 𝑎 𝑅 𝑏 ,  𝑎 ,  𝑏 )  =  𝑎 ) | 
						
							| 32 | 30 31 | sylan9eqr | ⊢ ( ( 𝑎 𝑅 𝑏  ∧  ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) ) )  →  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  =  𝑎 ) | 
						
							| 33 | 32 | eqeq2d | ⊢ ( ( 𝑎 𝑅 𝑏  ∧  ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) ) )  →  ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  ↔  inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎 ) ) | 
						
							| 34 |  | suppr | ⊢ ( ( 𝑅  Or  𝑉  ∧  𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 )  →  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  =  if ( 𝑏 𝑅 𝑎 ,  𝑎 ,  𝑏 ) ) | 
						
							| 35 | 34 | 3expb | ⊢ ( ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  →  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  =  if ( 𝑏 𝑅 𝑎 ,  𝑎 ,  𝑏 ) ) | 
						
							| 36 | 35 | adantl | ⊢ ( ( 𝑎 𝑅 𝑏  ∧  ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) ) )  →  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  =  if ( 𝑏 𝑅 𝑎 ,  𝑎 ,  𝑏 ) ) | 
						
							| 37 |  | sotric | ⊢ ( ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  →  ( 𝑎 𝑅 𝑏  ↔  ¬  ( 𝑎  =  𝑏  ∨  𝑏 𝑅 𝑎 ) ) ) | 
						
							| 38 |  | ioran | ⊢ ( ¬  ( 𝑎  =  𝑏  ∨  𝑏 𝑅 𝑎 )  ↔  ( ¬  𝑎  =  𝑏  ∧  ¬  𝑏 𝑅 𝑎 ) ) | 
						
							| 39 |  | iffalse | ⊢ ( ¬  𝑏 𝑅 𝑎  →  if ( 𝑏 𝑅 𝑎 ,  𝑎 ,  𝑏 )  =  𝑏 ) | 
						
							| 40 | 38 39 | simplbiim | ⊢ ( ¬  ( 𝑎  =  𝑏  ∨  𝑏 𝑅 𝑎 )  →  if ( 𝑏 𝑅 𝑎 ,  𝑎 ,  𝑏 )  =  𝑏 ) | 
						
							| 41 | 37 40 | biimtrdi | ⊢ ( ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  →  ( 𝑎 𝑅 𝑏  →  if ( 𝑏 𝑅 𝑎 ,  𝑎 ,  𝑏 )  =  𝑏 ) ) | 
						
							| 42 | 41 | impcom | ⊢ ( ( 𝑎 𝑅 𝑏  ∧  ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) ) )  →  if ( 𝑏 𝑅 𝑎 ,  𝑎 ,  𝑏 )  =  𝑏 ) | 
						
							| 43 | 36 42 | eqtrd | ⊢ ( ( 𝑎 𝑅 𝑏  ∧  ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) ) )  →  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  =  𝑏 ) | 
						
							| 44 | 43 | eqeq2d | ⊢ ( ( 𝑎 𝑅 𝑏  ∧  ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) ) )  →  ( sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  ↔  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏 ) ) | 
						
							| 45 | 33 44 | anbi12d | ⊢ ( ( 𝑎 𝑅 𝑏  ∧  ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) ) )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) )  ↔  ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏 ) ) ) | 
						
							| 46 | 45 | adantr | ⊢ ( ( ( 𝑎 𝑅 𝑏  ∧  ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) ) )  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) )  ↔  ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏 ) ) ) | 
						
							| 47 |  | solin | ⊢ ( ( 𝑅  Or  𝑉  ∧  ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 ) )  →  ( 𝑐 𝑅 𝑑  ∨  𝑐  =  𝑑  ∨  𝑑 𝑅 𝑐 ) ) | 
						
							| 48 | 47 | adantrr | ⊢ ( ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) )  →  ( 𝑐 𝑅 𝑑  ∨  𝑐  =  𝑑  ∨  𝑑 𝑅 𝑐 ) ) | 
						
							| 49 |  | simpl | ⊢ ( ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) )  →  𝑅  Or  𝑉 ) | 
						
							| 50 |  | simprll | ⊢ ( ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) )  →  𝑐  ∈  𝑉 ) | 
						
							| 51 |  | simprlr | ⊢ ( ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) )  →  𝑑  ∈  𝑉 ) | 
						
							| 52 |  | infpr | ⊢ ( ( 𝑅  Or  𝑉  ∧  𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  →  inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  if ( 𝑐 𝑅 𝑑 ,  𝑐 ,  𝑑 ) ) | 
						
							| 53 | 49 50 51 52 | syl3anc | ⊢ ( ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) )  →  inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  if ( 𝑐 𝑅 𝑑 ,  𝑐 ,  𝑑 ) ) | 
						
							| 54 |  | iftrue | ⊢ ( 𝑐 𝑅 𝑑  →  if ( 𝑐 𝑅 𝑑 ,  𝑐 ,  𝑑 )  =  𝑐 ) | 
						
							| 55 | 53 54 | sylan9eqr | ⊢ ( ( 𝑐 𝑅 𝑑  ∧  ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) ) )  →  inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑐 ) | 
						
							| 56 | 55 | eqeq1d | ⊢ ( ( 𝑐 𝑅 𝑑  ∧  ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) ) )  →  ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎  ↔  𝑐  =  𝑎 ) ) | 
						
							| 57 |  | suppr | ⊢ ( ( 𝑅  Or  𝑉  ∧  𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  →  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  if ( 𝑑 𝑅 𝑐 ,  𝑐 ,  𝑑 ) ) | 
						
							| 58 | 49 50 51 57 | syl3anc | ⊢ ( ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) )  →  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  if ( 𝑑 𝑅 𝑐 ,  𝑐 ,  𝑑 ) ) | 
						
							| 59 | 58 | adantl | ⊢ ( ( 𝑐 𝑅 𝑑  ∧  ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) ) )  →  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  if ( 𝑑 𝑅 𝑐 ,  𝑐 ,  𝑑 ) ) | 
						
							| 60 |  | sotric | ⊢ ( ( 𝑅  Or  𝑉  ∧  ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 ) )  →  ( 𝑐 𝑅 𝑑  ↔  ¬  ( 𝑐  =  𝑑  ∨  𝑑 𝑅 𝑐 ) ) ) | 
						
							| 61 | 60 | adantrr | ⊢ ( ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) )  →  ( 𝑐 𝑅 𝑑  ↔  ¬  ( 𝑐  =  𝑑  ∨  𝑑 𝑅 𝑐 ) ) ) | 
						
							| 62 |  | ioran | ⊢ ( ¬  ( 𝑐  =  𝑑  ∨  𝑑 𝑅 𝑐 )  ↔  ( ¬  𝑐  =  𝑑  ∧  ¬  𝑑 𝑅 𝑐 ) ) | 
						
							| 63 |  | iffalse | ⊢ ( ¬  𝑑 𝑅 𝑐  →  if ( 𝑑 𝑅 𝑐 ,  𝑐 ,  𝑑 )  =  𝑑 ) | 
						
							| 64 | 62 63 | simplbiim | ⊢ ( ¬  ( 𝑐  =  𝑑  ∨  𝑑 𝑅 𝑐 )  →  if ( 𝑑 𝑅 𝑐 ,  𝑐 ,  𝑑 )  =  𝑑 ) | 
						
							| 65 | 61 64 | biimtrdi | ⊢ ( ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) )  →  ( 𝑐 𝑅 𝑑  →  if ( 𝑑 𝑅 𝑐 ,  𝑐 ,  𝑑 )  =  𝑑 ) ) | 
						
							| 66 | 65 | impcom | ⊢ ( ( 𝑐 𝑅 𝑑  ∧  ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) ) )  →  if ( 𝑑 𝑅 𝑐 ,  𝑐 ,  𝑑 )  =  𝑑 ) | 
						
							| 67 | 59 66 | eqtrd | ⊢ ( ( 𝑐 𝑅 𝑑  ∧  ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) ) )  →  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑑 ) | 
						
							| 68 | 67 | eqeq1d | ⊢ ( ( 𝑐 𝑅 𝑑  ∧  ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) ) )  →  ( sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏  ↔  𝑑  =  𝑏 ) ) | 
						
							| 69 | 56 68 | anbi12d | ⊢ ( ( 𝑐 𝑅 𝑑  ∧  ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) ) )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏 )  ↔  ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 ) ) ) | 
						
							| 70 |  | orc | ⊢ ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) | 
						
							| 71 | 69 70 | biimtrdi | ⊢ ( ( 𝑐 𝑅 𝑑  ∧  ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) ) )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏 )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) | 
						
							| 72 | 71 | ex | ⊢ ( 𝑐 𝑅 𝑑  →  ( ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏 )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) ) | 
						
							| 73 |  | eqneqall | ⊢ ( 𝑐  =  𝑑  →  ( 𝑐  ≠  𝑑  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏 )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) ) | 
						
							| 74 | 73 | adantld | ⊢ ( 𝑐  =  𝑑  →  ( ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏 )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) ) | 
						
							| 75 | 74 | adantld | ⊢ ( 𝑐  =  𝑑  →  ( ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏 )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) ) | 
						
							| 76 | 53 | adantl | ⊢ ( ( 𝑑 𝑅 𝑐  ∧  ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) ) )  →  inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  if ( 𝑐 𝑅 𝑑 ,  𝑐 ,  𝑑 ) ) | 
						
							| 77 | 76 | eqeq1d | ⊢ ( ( 𝑑 𝑅 𝑐  ∧  ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) ) )  →  ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎  ↔  if ( 𝑐 𝑅 𝑑 ,  𝑐 ,  𝑑 )  =  𝑎 ) ) | 
						
							| 78 |  | iftrue | ⊢ ( 𝑑 𝑅 𝑐  →  if ( 𝑑 𝑅 𝑐 ,  𝑐 ,  𝑑 )  =  𝑐 ) | 
						
							| 79 | 58 78 | sylan9eqr | ⊢ ( ( 𝑑 𝑅 𝑐  ∧  ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) ) )  →  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑐 ) | 
						
							| 80 | 79 | eqeq1d | ⊢ ( ( 𝑑 𝑅 𝑐  ∧  ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) ) )  →  ( sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏  ↔  𝑐  =  𝑏 ) ) | 
						
							| 81 | 77 80 | anbi12d | ⊢ ( ( 𝑑 𝑅 𝑐  ∧  ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) ) )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏 )  ↔  ( if ( 𝑐 𝑅 𝑑 ,  𝑐 ,  𝑑 )  =  𝑎  ∧  𝑐  =  𝑏 ) ) ) | 
						
							| 82 |  | simpl | ⊢ ( ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 )  →  ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 ) ) | 
						
							| 83 | 82 | ancomd | ⊢ ( ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 )  →  ( 𝑑  ∈  𝑉  ∧  𝑐  ∈  𝑉 ) ) | 
						
							| 84 |  | sotric | ⊢ ( ( 𝑅  Or  𝑉  ∧  ( 𝑑  ∈  𝑉  ∧  𝑐  ∈  𝑉 ) )  →  ( 𝑑 𝑅 𝑐  ↔  ¬  ( 𝑑  =  𝑐  ∨  𝑐 𝑅 𝑑 ) ) ) | 
						
							| 85 | 83 84 | sylan2 | ⊢ ( ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) )  →  ( 𝑑 𝑅 𝑐  ↔  ¬  ( 𝑑  =  𝑐  ∨  𝑐 𝑅 𝑑 ) ) ) | 
						
							| 86 |  | ioran | ⊢ ( ¬  ( 𝑑  =  𝑐  ∨  𝑐 𝑅 𝑑 )  ↔  ( ¬  𝑑  =  𝑐  ∧  ¬  𝑐 𝑅 𝑑 ) ) | 
						
							| 87 |  | iffalse | ⊢ ( ¬  𝑐 𝑅 𝑑  →  if ( 𝑐 𝑅 𝑑 ,  𝑐 ,  𝑑 )  =  𝑑 ) | 
						
							| 88 | 86 87 | simplbiim | ⊢ ( ¬  ( 𝑑  =  𝑐  ∨  𝑐 𝑅 𝑑 )  →  if ( 𝑐 𝑅 𝑑 ,  𝑐 ,  𝑑 )  =  𝑑 ) | 
						
							| 89 | 88 | eqeq1d | ⊢ ( ¬  ( 𝑑  =  𝑐  ∨  𝑐 𝑅 𝑑 )  →  ( if ( 𝑐 𝑅 𝑑 ,  𝑐 ,  𝑑 )  =  𝑎  ↔  𝑑  =  𝑎 ) ) | 
						
							| 90 | 85 89 | biimtrdi | ⊢ ( ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) )  →  ( 𝑑 𝑅 𝑐  →  ( if ( 𝑐 𝑅 𝑑 ,  𝑐 ,  𝑑 )  =  𝑎  ↔  𝑑  =  𝑎 ) ) ) | 
						
							| 91 | 90 | impcom | ⊢ ( ( 𝑑 𝑅 𝑐  ∧  ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) ) )  →  ( if ( 𝑐 𝑅 𝑑 ,  𝑐 ,  𝑑 )  =  𝑎  ↔  𝑑  =  𝑎 ) ) | 
						
							| 92 | 91 | anbi1d | ⊢ ( ( 𝑑 𝑅 𝑐  ∧  ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) ) )  →  ( ( if ( 𝑐 𝑅 𝑑 ,  𝑐 ,  𝑑 )  =  𝑎  ∧  𝑐  =  𝑏 )  ↔  ( 𝑑  =  𝑎  ∧  𝑐  =  𝑏 ) ) ) | 
						
							| 93 |  | olc | ⊢ ( ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) | 
						
							| 94 | 93 | ancoms | ⊢ ( ( 𝑑  =  𝑎  ∧  𝑐  =  𝑏 )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) | 
						
							| 95 | 92 94 | biimtrdi | ⊢ ( ( 𝑑 𝑅 𝑐  ∧  ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) ) )  →  ( ( if ( 𝑐 𝑅 𝑑 ,  𝑐 ,  𝑑 )  =  𝑎  ∧  𝑐  =  𝑏 )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) | 
						
							| 96 | 81 95 | sylbid | ⊢ ( ( 𝑑 𝑅 𝑐  ∧  ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) ) )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏 )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) | 
						
							| 97 | 96 | ex | ⊢ ( 𝑑 𝑅 𝑐  →  ( ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏 )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) ) | 
						
							| 98 | 72 75 97 | 3jaoi | ⊢ ( ( 𝑐 𝑅 𝑑  ∨  𝑐  =  𝑑  ∨  𝑑 𝑅 𝑐 )  →  ( ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏 )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) ) | 
						
							| 99 | 48 98 | mpcom | ⊢ ( ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏 )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) | 
						
							| 100 | 99 | ex | ⊢ ( 𝑅  Or  𝑉  →  ( ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏 )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) ) | 
						
							| 101 | 100 | ad2antrl | ⊢ ( ( 𝑎 𝑅 𝑏  ∧  ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) ) )  →  ( ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏 )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) ) | 
						
							| 102 | 101 | imp | ⊢ ( ( ( 𝑎 𝑅 𝑏  ∧  ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) ) )  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏 )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) | 
						
							| 103 | 46 102 | sylbid | ⊢ ( ( ( 𝑎 𝑅 𝑏  ∧  ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) ) )  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) | 
						
							| 104 | 103 | ex | ⊢ ( ( 𝑎 𝑅 𝑏  ∧  ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) ) )  →  ( ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) ) | 
						
							| 105 | 104 | a1d | ⊢ ( ( 𝑎 𝑅 𝑏  ∧  ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) ) )  →  ( 𝑎  ≠  𝑏  →  ( ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) ) ) | 
						
							| 106 | 105 | ex | ⊢ ( 𝑎 𝑅 𝑏  →  ( ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  →  ( 𝑎  ≠  𝑏  →  ( ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) ) ) ) | 
						
							| 107 |  | eqneqall | ⊢ ( 𝑎  =  𝑏  →  ( 𝑎  ≠  𝑏  →  ( ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) ) ) | 
						
							| 108 | 107 | a1d | ⊢ ( 𝑎  =  𝑏  →  ( ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  →  ( 𝑎  ≠  𝑏  →  ( ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) ) ) ) | 
						
							| 109 | 30 | adantl | ⊢ ( ( 𝑏 𝑅 𝑎  ∧  ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) ) )  →  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  =  if ( 𝑎 𝑅 𝑏 ,  𝑎 ,  𝑏 ) ) | 
						
							| 110 |  | sotric | ⊢ ( ( 𝑅  Or  𝑉  ∧  ( 𝑏  ∈  𝑉  ∧  𝑎  ∈  𝑉 ) )  →  ( 𝑏 𝑅 𝑎  ↔  ¬  ( 𝑏  =  𝑎  ∨  𝑎 𝑅 𝑏 ) ) ) | 
						
							| 111 | 110 | ancom2s | ⊢ ( ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  →  ( 𝑏 𝑅 𝑎  ↔  ¬  ( 𝑏  =  𝑎  ∨  𝑎 𝑅 𝑏 ) ) ) | 
						
							| 112 |  | ioran | ⊢ ( ¬  ( 𝑏  =  𝑎  ∨  𝑎 𝑅 𝑏 )  ↔  ( ¬  𝑏  =  𝑎  ∧  ¬  𝑎 𝑅 𝑏 ) ) | 
						
							| 113 |  | iffalse | ⊢ ( ¬  𝑎 𝑅 𝑏  →  if ( 𝑎 𝑅 𝑏 ,  𝑎 ,  𝑏 )  =  𝑏 ) | 
						
							| 114 | 112 113 | simplbiim | ⊢ ( ¬  ( 𝑏  =  𝑎  ∨  𝑎 𝑅 𝑏 )  →  if ( 𝑎 𝑅 𝑏 ,  𝑎 ,  𝑏 )  =  𝑏 ) | 
						
							| 115 | 111 114 | biimtrdi | ⊢ ( ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  →  ( 𝑏 𝑅 𝑎  →  if ( 𝑎 𝑅 𝑏 ,  𝑎 ,  𝑏 )  =  𝑏 ) ) | 
						
							| 116 | 115 | impcom | ⊢ ( ( 𝑏 𝑅 𝑎  ∧  ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) ) )  →  if ( 𝑎 𝑅 𝑏 ,  𝑎 ,  𝑏 )  =  𝑏 ) | 
						
							| 117 | 109 116 | eqtrd | ⊢ ( ( 𝑏 𝑅 𝑎  ∧  ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) ) )  →  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  =  𝑏 ) | 
						
							| 118 | 117 | eqeq2d | ⊢ ( ( 𝑏 𝑅 𝑎  ∧  ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) ) )  →  ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  ↔  inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏 ) ) | 
						
							| 119 |  | iftrue | ⊢ ( 𝑏 𝑅 𝑎  →  if ( 𝑏 𝑅 𝑎 ,  𝑎 ,  𝑏 )  =  𝑎 ) | 
						
							| 120 | 35 119 | sylan9eqr | ⊢ ( ( 𝑏 𝑅 𝑎  ∧  ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) ) )  →  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  =  𝑎 ) | 
						
							| 121 | 120 | eqeq2d | ⊢ ( ( 𝑏 𝑅 𝑎  ∧  ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) ) )  →  ( sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  ↔  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎 ) ) | 
						
							| 122 | 118 121 | anbi12d | ⊢ ( ( 𝑏 𝑅 𝑎  ∧  ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) ) )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) )  ↔  ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎 ) ) ) | 
						
							| 123 | 122 | adantr | ⊢ ( ( ( 𝑏 𝑅 𝑎  ∧  ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) ) )  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) )  ↔  ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎 ) ) ) | 
						
							| 124 | 55 | eqeq1d | ⊢ ( ( 𝑐 𝑅 𝑑  ∧  ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) ) )  →  ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏  ↔  𝑐  =  𝑏 ) ) | 
						
							| 125 | 67 | eqeq1d | ⊢ ( ( 𝑐 𝑅 𝑑  ∧  ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) ) )  →  ( sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎  ↔  𝑑  =  𝑎 ) ) | 
						
							| 126 | 124 125 | anbi12d | ⊢ ( ( 𝑐 𝑅 𝑑  ∧  ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) ) )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎 )  ↔  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) | 
						
							| 127 | 126 93 | biimtrdi | ⊢ ( ( 𝑐 𝑅 𝑑  ∧  ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) ) )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎 )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) | 
						
							| 128 | 127 | ex | ⊢ ( 𝑐 𝑅 𝑑  →  ( ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎 )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) ) | 
						
							| 129 |  | eqneqall | ⊢ ( 𝑐  =  𝑑  →  ( 𝑐  ≠  𝑑  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎 )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) ) | 
						
							| 130 | 129 | adantld | ⊢ ( 𝑐  =  𝑑  →  ( ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎 )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) ) | 
						
							| 131 | 130 | adantld | ⊢ ( 𝑐  =  𝑑  →  ( ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎 )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) ) | 
						
							| 132 | 85 88 | biimtrdi | ⊢ ( ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) )  →  ( 𝑑 𝑅 𝑐  →  if ( 𝑐 𝑅 𝑑 ,  𝑐 ,  𝑑 )  =  𝑑 ) ) | 
						
							| 133 | 132 | impcom | ⊢ ( ( 𝑑 𝑅 𝑐  ∧  ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) ) )  →  if ( 𝑐 𝑅 𝑑 ,  𝑐 ,  𝑑 )  =  𝑑 ) | 
						
							| 134 | 76 133 | eqtrd | ⊢ ( ( 𝑑 𝑅 𝑐  ∧  ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) ) )  →  inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑑 ) | 
						
							| 135 | 134 | eqeq1d | ⊢ ( ( 𝑑 𝑅 𝑐  ∧  ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) ) )  →  ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏  ↔  𝑑  =  𝑏 ) ) | 
						
							| 136 | 79 | eqeq1d | ⊢ ( ( 𝑑 𝑅 𝑐  ∧  ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) ) )  →  ( sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎  ↔  𝑐  =  𝑎 ) ) | 
						
							| 137 | 135 136 | anbi12d | ⊢ ( ( 𝑑 𝑅 𝑐  ∧  ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) ) )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎 )  ↔  ( 𝑑  =  𝑏  ∧  𝑐  =  𝑎 ) ) ) | 
						
							| 138 | 70 | ancoms | ⊢ ( ( 𝑑  =  𝑏  ∧  𝑐  =  𝑎 )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) | 
						
							| 139 | 137 138 | biimtrdi | ⊢ ( ( 𝑑 𝑅 𝑐  ∧  ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) ) )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎 )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) | 
						
							| 140 | 139 | ex | ⊢ ( 𝑑 𝑅 𝑐  →  ( ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎 )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) ) | 
						
							| 141 | 128 131 140 | 3jaoi | ⊢ ( ( 𝑐 𝑅 𝑑  ∨  𝑐  =  𝑑  ∨  𝑑 𝑅 𝑐 )  →  ( ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎 )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) ) | 
						
							| 142 | 48 141 | mpcom | ⊢ ( ( 𝑅  Or  𝑉  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎 )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) | 
						
							| 143 | 142 | ex | ⊢ ( 𝑅  Or  𝑉  →  ( ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎 )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) ) | 
						
							| 144 | 143 | ad2antrl | ⊢ ( ( 𝑏 𝑅 𝑎  ∧  ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) ) )  →  ( ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎 )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) ) | 
						
							| 145 | 144 | imp | ⊢ ( ( ( 𝑏 𝑅 𝑎  ∧  ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) ) )  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑏  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  𝑎 )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) | 
						
							| 146 | 123 145 | sylbid | ⊢ ( ( ( 𝑏 𝑅 𝑎  ∧  ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) ) )  ∧  ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 ) )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) | 
						
							| 147 | 146 | ex | ⊢ ( ( 𝑏 𝑅 𝑎  ∧  ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) ) )  →  ( ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) ) | 
						
							| 148 | 147 | a1d | ⊢ ( ( 𝑏 𝑅 𝑎  ∧  ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) ) )  →  ( 𝑎  ≠  𝑏  →  ( ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) ) ) | 
						
							| 149 | 148 | ex | ⊢ ( 𝑏 𝑅 𝑎  →  ( ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  →  ( 𝑎  ≠  𝑏  →  ( ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) ) ) ) | 
						
							| 150 | 106 108 149 | 3jaoi | ⊢ ( ( 𝑎 𝑅 𝑏  ∨  𝑎  =  𝑏  ∨  𝑏 𝑅 𝑎 )  →  ( ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  →  ( 𝑎  ≠  𝑏  →  ( ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) ) ) ) | 
						
							| 151 | 28 150 | mpcom | ⊢ ( ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  →  ( 𝑎  ≠  𝑏  →  ( ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) ) ) | 
						
							| 152 | 151 | adantld | ⊢ ( ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  →  ( ( 𝑊  =  { 𝑎 ,  𝑏 }  ∧  𝑎  ≠  𝑏 )  →  ( ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) ) ) | 
						
							| 153 | 152 | imp | ⊢ ( ( ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  ∧  ( 𝑊  =  { 𝑎 ,  𝑏 }  ∧  𝑎  ≠  𝑏 ) )  →  ( ( ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 )  ∧  𝑐  ≠  𝑑 )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) ) | 
						
							| 154 | 153 | expdimp | ⊢ ( ( ( ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  ∧  ( 𝑊  =  { 𝑎 ,  𝑏 }  ∧  𝑎  ≠  𝑏 ) )  ∧  ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 ) )  →  ( 𝑐  ≠  𝑑  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) ) | 
						
							| 155 | 154 | adantld | ⊢ ( ( ( ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  ∧  ( 𝑊  =  { 𝑎 ,  𝑏 }  ∧  𝑎  ≠  𝑏 ) )  ∧  ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 ) )  →  ( ( 𝑍  =  { 𝑐 ,  𝑑 }  ∧  𝑐  ≠  𝑑 )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) ) | 
						
							| 156 | 155 | imp | ⊢ ( ( ( ( ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  ∧  ( 𝑊  =  { 𝑎 ,  𝑏 }  ∧  𝑎  ≠  𝑏 ) )  ∧  ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 ) )  ∧  ( 𝑍  =  { 𝑐 ,  𝑑 }  ∧  𝑐  ≠  𝑑 ) )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) )  →  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) ) | 
						
							| 157 |  | vex | ⊢ 𝑐  ∈  V | 
						
							| 158 |  | vex | ⊢ 𝑑  ∈  V | 
						
							| 159 |  | vex | ⊢ 𝑎  ∈  V | 
						
							| 160 |  | vex | ⊢ 𝑏  ∈  V | 
						
							| 161 | 157 158 159 160 | preq12b | ⊢ ( { 𝑐 ,  𝑑 }  =  { 𝑎 ,  𝑏 }  ↔  ( ( 𝑐  =  𝑎  ∧  𝑑  =  𝑏 )  ∨  ( 𝑐  =  𝑏  ∧  𝑑  =  𝑎 ) ) ) | 
						
							| 162 | 156 161 | imbitrrdi | ⊢ ( ( ( ( ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  ∧  ( 𝑊  =  { 𝑎 ,  𝑏 }  ∧  𝑎  ≠  𝑏 ) )  ∧  ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 ) )  ∧  ( 𝑍  =  { 𝑐 ,  𝑑 }  ∧  𝑐  ≠  𝑑 ) )  →  ( ( inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 )  ∧  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 )  =  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) )  →  { 𝑐 ,  𝑑 }  =  { 𝑎 ,  𝑏 } ) ) | 
						
							| 163 | 27 162 | sylbid | ⊢ ( ( ( ( ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  ∧  ( 𝑊  =  { 𝑎 ,  𝑏 }  ∧  𝑎  ≠  𝑏 ) )  ∧  ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 ) )  ∧  ( 𝑍  =  { 𝑐 ,  𝑑 }  ∧  𝑐  ≠  𝑑 ) )  →  ( 〈 inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 ) ,  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) ,  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) 〉  →  { 𝑐 ,  𝑑 }  =  { 𝑎 ,  𝑏 } ) ) | 
						
							| 164 |  | infeq1 | ⊢ ( 𝑍  =  { 𝑐 ,  𝑑 }  →  inf ( 𝑍 ,  𝑉 ,  𝑅 )  =  inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 ) ) | 
						
							| 165 |  | supeq1 | ⊢ ( 𝑍  =  { 𝑐 ,  𝑑 }  →  sup ( 𝑍 ,  𝑉 ,  𝑅 )  =  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 ) ) | 
						
							| 166 | 164 165 | opeq12d | ⊢ ( 𝑍  =  { 𝑐 ,  𝑑 }  →  〈 inf ( 𝑍 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑍 ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 ) ,  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 ) 〉 ) | 
						
							| 167 |  | infeq1 | ⊢ ( 𝑊  =  { 𝑎 ,  𝑏 }  →  inf ( 𝑊 ,  𝑉 ,  𝑅 )  =  inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) ) | 
						
							| 168 |  | supeq1 | ⊢ ( 𝑊  =  { 𝑎 ,  𝑏 }  →  sup ( 𝑊 ,  𝑉 ,  𝑅 )  =  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) ) | 
						
							| 169 | 167 168 | opeq12d | ⊢ ( 𝑊  =  { 𝑎 ,  𝑏 }  →  〈 inf ( 𝑊 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑊 ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) ,  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) 〉 ) | 
						
							| 170 | 166 169 | eqeqan12rd | ⊢ ( ( 𝑊  =  { 𝑎 ,  𝑏 }  ∧  𝑍  =  { 𝑐 ,  𝑑 } )  →  ( 〈 inf ( 𝑍 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑍 ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( 𝑊 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑊 ,  𝑉 ,  𝑅 ) 〉  ↔  〈 inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 ) ,  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) ,  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) 〉 ) ) | 
						
							| 171 |  | eqeq12 | ⊢ ( ( 𝑍  =  { 𝑐 ,  𝑑 }  ∧  𝑊  =  { 𝑎 ,  𝑏 } )  →  ( 𝑍  =  𝑊  ↔  { 𝑐 ,  𝑑 }  =  { 𝑎 ,  𝑏 } ) ) | 
						
							| 172 | 171 | ancoms | ⊢ ( ( 𝑊  =  { 𝑎 ,  𝑏 }  ∧  𝑍  =  { 𝑐 ,  𝑑 } )  →  ( 𝑍  =  𝑊  ↔  { 𝑐 ,  𝑑 }  =  { 𝑎 ,  𝑏 } ) ) | 
						
							| 173 | 170 172 | imbi12d | ⊢ ( ( 𝑊  =  { 𝑎 ,  𝑏 }  ∧  𝑍  =  { 𝑐 ,  𝑑 } )  →  ( ( 〈 inf ( 𝑍 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑍 ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( 𝑊 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑊 ,  𝑉 ,  𝑅 ) 〉  →  𝑍  =  𝑊 )  ↔  ( 〈 inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 ) ,  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) ,  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) 〉  →  { 𝑐 ,  𝑑 }  =  { 𝑎 ,  𝑏 } ) ) ) | 
						
							| 174 | 173 | ex | ⊢ ( 𝑊  =  { 𝑎 ,  𝑏 }  →  ( 𝑍  =  { 𝑐 ,  𝑑 }  →  ( ( 〈 inf ( 𝑍 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑍 ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( 𝑊 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑊 ,  𝑉 ,  𝑅 ) 〉  →  𝑍  =  𝑊 )  ↔  ( 〈 inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 ) ,  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) ,  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) 〉  →  { 𝑐 ,  𝑑 }  =  { 𝑎 ,  𝑏 } ) ) ) ) | 
						
							| 175 | 174 | ad2antrl | ⊢ ( ( ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  ∧  ( 𝑊  =  { 𝑎 ,  𝑏 }  ∧  𝑎  ≠  𝑏 ) )  →  ( 𝑍  =  { 𝑐 ,  𝑑 }  →  ( ( 〈 inf ( 𝑍 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑍 ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( 𝑊 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑊 ,  𝑉 ,  𝑅 ) 〉  →  𝑍  =  𝑊 )  ↔  ( 〈 inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 ) ,  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) ,  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) 〉  →  { 𝑐 ,  𝑑 }  =  { 𝑎 ,  𝑏 } ) ) ) ) | 
						
							| 176 | 175 | adantr | ⊢ ( ( ( ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  ∧  ( 𝑊  =  { 𝑎 ,  𝑏 }  ∧  𝑎  ≠  𝑏 ) )  ∧  ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 ) )  →  ( 𝑍  =  { 𝑐 ,  𝑑 }  →  ( ( 〈 inf ( 𝑍 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑍 ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( 𝑊 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑊 ,  𝑉 ,  𝑅 ) 〉  →  𝑍  =  𝑊 )  ↔  ( 〈 inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 ) ,  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) ,  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) 〉  →  { 𝑐 ,  𝑑 }  =  { 𝑎 ,  𝑏 } ) ) ) ) | 
						
							| 177 | 176 | com12 | ⊢ ( 𝑍  =  { 𝑐 ,  𝑑 }  →  ( ( ( ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  ∧  ( 𝑊  =  { 𝑎 ,  𝑏 }  ∧  𝑎  ≠  𝑏 ) )  ∧  ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 ) )  →  ( ( 〈 inf ( 𝑍 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑍 ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( 𝑊 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑊 ,  𝑉 ,  𝑅 ) 〉  →  𝑍  =  𝑊 )  ↔  ( 〈 inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 ) ,  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) ,  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) 〉  →  { 𝑐 ,  𝑑 }  =  { 𝑎 ,  𝑏 } ) ) ) ) | 
						
							| 178 | 177 | adantr | ⊢ ( ( 𝑍  =  { 𝑐 ,  𝑑 }  ∧  𝑐  ≠  𝑑 )  →  ( ( ( ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  ∧  ( 𝑊  =  { 𝑎 ,  𝑏 }  ∧  𝑎  ≠  𝑏 ) )  ∧  ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 ) )  →  ( ( 〈 inf ( 𝑍 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑍 ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( 𝑊 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑊 ,  𝑉 ,  𝑅 ) 〉  →  𝑍  =  𝑊 )  ↔  ( 〈 inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 ) ,  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) ,  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) 〉  →  { 𝑐 ,  𝑑 }  =  { 𝑎 ,  𝑏 } ) ) ) ) | 
						
							| 179 | 178 | impcom | ⊢ ( ( ( ( ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  ∧  ( 𝑊  =  { 𝑎 ,  𝑏 }  ∧  𝑎  ≠  𝑏 ) )  ∧  ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 ) )  ∧  ( 𝑍  =  { 𝑐 ,  𝑑 }  ∧  𝑐  ≠  𝑑 ) )  →  ( ( 〈 inf ( 𝑍 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑍 ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( 𝑊 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑊 ,  𝑉 ,  𝑅 ) 〉  →  𝑍  =  𝑊 )  ↔  ( 〈 inf ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 ) ,  sup ( { 𝑐 ,  𝑑 } ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) ,  sup ( { 𝑎 ,  𝑏 } ,  𝑉 ,  𝑅 ) 〉  →  { 𝑐 ,  𝑑 }  =  { 𝑎 ,  𝑏 } ) ) ) | 
						
							| 180 | 163 179 | mpbird | ⊢ ( ( ( ( ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  ∧  ( 𝑊  =  { 𝑎 ,  𝑏 }  ∧  𝑎  ≠  𝑏 ) )  ∧  ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 ) )  ∧  ( 𝑍  =  { 𝑐 ,  𝑑 }  ∧  𝑐  ≠  𝑑 ) )  →  ( 〈 inf ( 𝑍 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑍 ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( 𝑊 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑊 ,  𝑉 ,  𝑅 ) 〉  →  𝑍  =  𝑊 ) ) | 
						
							| 181 | 180 | ex | ⊢ ( ( ( ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  ∧  ( 𝑊  =  { 𝑎 ,  𝑏 }  ∧  𝑎  ≠  𝑏 ) )  ∧  ( 𝑐  ∈  𝑉  ∧  𝑑  ∈  𝑉 ) )  →  ( ( 𝑍  =  { 𝑐 ,  𝑑 }  ∧  𝑐  ≠  𝑑 )  →  ( 〈 inf ( 𝑍 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑍 ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( 𝑊 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑊 ,  𝑉 ,  𝑅 ) 〉  →  𝑍  =  𝑊 ) ) ) | 
						
							| 182 | 181 | rexlimdvva | ⊢ ( ( ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  ∧  ( 𝑊  =  { 𝑎 ,  𝑏 }  ∧  𝑎  ≠  𝑏 ) )  →  ( ∃ 𝑐  ∈  𝑉 ∃ 𝑑  ∈  𝑉 ( 𝑍  =  { 𝑐 ,  𝑑 }  ∧  𝑐  ≠  𝑑 )  →  ( 〈 inf ( 𝑍 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑍 ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( 𝑊 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑊 ,  𝑉 ,  𝑅 ) 〉  →  𝑍  =  𝑊 ) ) ) | 
						
							| 183 | 182 | ex | ⊢ ( ( 𝑅  Or  𝑉  ∧  ( 𝑎  ∈  𝑉  ∧  𝑏  ∈  𝑉 ) )  →  ( ( 𝑊  =  { 𝑎 ,  𝑏 }  ∧  𝑎  ≠  𝑏 )  →  ( ∃ 𝑐  ∈  𝑉 ∃ 𝑑  ∈  𝑉 ( 𝑍  =  { 𝑐 ,  𝑑 }  ∧  𝑐  ≠  𝑑 )  →  ( 〈 inf ( 𝑍 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑍 ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( 𝑊 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑊 ,  𝑉 ,  𝑅 ) 〉  →  𝑍  =  𝑊 ) ) ) ) | 
						
							| 184 | 183 | rexlimdvva | ⊢ ( 𝑅  Or  𝑉  →  ( ∃ 𝑎  ∈  𝑉 ∃ 𝑏  ∈  𝑉 ( 𝑊  =  { 𝑎 ,  𝑏 }  ∧  𝑎  ≠  𝑏 )  →  ( ∃ 𝑐  ∈  𝑉 ∃ 𝑑  ∈  𝑉 ( 𝑍  =  { 𝑐 ,  𝑑 }  ∧  𝑐  ≠  𝑑 )  →  ( 〈 inf ( 𝑍 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑍 ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( 𝑊 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑊 ,  𝑉 ,  𝑅 ) 〉  →  𝑍  =  𝑊 ) ) ) ) | 
						
							| 185 | 184 | com13 | ⊢ ( ∃ 𝑐  ∈  𝑉 ∃ 𝑑  ∈  𝑉 ( 𝑍  =  { 𝑐 ,  𝑑 }  ∧  𝑐  ≠  𝑑 )  →  ( ∃ 𝑎  ∈  𝑉 ∃ 𝑏  ∈  𝑉 ( 𝑊  =  { 𝑎 ,  𝑏 }  ∧  𝑎  ≠  𝑏 )  →  ( 𝑅  Or  𝑉  →  ( 〈 inf ( 𝑍 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑍 ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( 𝑊 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑊 ,  𝑉 ,  𝑅 ) 〉  →  𝑍  =  𝑊 ) ) ) ) | 
						
							| 186 | 20 185 | biimtrid | ⊢ ( ∃ 𝑐  ∈  𝑉 ∃ 𝑑  ∈  𝑉 ( 𝑍  =  { 𝑐 ,  𝑑 }  ∧  𝑐  ≠  𝑑 )  →  ( 𝑊  ∈  𝑃  →  ( 𝑅  Or  𝑉  →  ( 〈 inf ( 𝑍 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑍 ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( 𝑊 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑊 ,  𝑉 ,  𝑅 ) 〉  →  𝑍  =  𝑊 ) ) ) ) | 
						
							| 187 | 19 186 | sylbi | ⊢ ( 𝑍  ∈  𝑃  →  ( 𝑊  ∈  𝑃  →  ( 𝑅  Or  𝑉  →  ( 〈 inf ( 𝑍 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑍 ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( 𝑊 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑊 ,  𝑉 ,  𝑅 ) 〉  →  𝑍  =  𝑊 ) ) ) ) | 
						
							| 188 | 187 | 3imp31 | ⊢ ( ( 𝑅  Or  𝑉  ∧  𝑊  ∈  𝑃  ∧  𝑍  ∈  𝑃 )  →  ( 〈 inf ( 𝑍 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑍 ,  𝑉 ,  𝑅 ) 〉  =  〈 inf ( 𝑊 ,  𝑉 ,  𝑅 ) ,  sup ( 𝑊 ,  𝑉 ,  𝑅 ) 〉  →  𝑍  =  𝑊 ) ) | 
						
							| 189 | 18 188 | sylbid | ⊢ ( ( 𝑅  Or  𝑉  ∧  𝑊  ∈  𝑃  ∧  𝑍  ∈  𝑃 )  →  ( ( 𝐹 ‘ 𝑍 )  =  ( 𝐹 ‘ 𝑊 )  →  𝑍  =  𝑊 ) ) |