| Step | Hyp | Ref | Expression | 
						
							| 1 |  | mdetuni.a | ⊢ 𝐴  =  ( 𝑁  Mat  𝑅 ) | 
						
							| 2 |  | mdetuni.b | ⊢ 𝐵  =  ( Base ‘ 𝐴 ) | 
						
							| 3 |  | mdetuni.k | ⊢ 𝐾  =  ( Base ‘ 𝑅 ) | 
						
							| 4 |  | mdetuni.0g | ⊢  0   =  ( 0g ‘ 𝑅 ) | 
						
							| 5 |  | mdetuni.1r | ⊢  1   =  ( 1r ‘ 𝑅 ) | 
						
							| 6 |  | mdetuni.pg | ⊢  +   =  ( +g ‘ 𝑅 ) | 
						
							| 7 |  | mdetuni.tg | ⊢  ·   =  ( .r ‘ 𝑅 ) | 
						
							| 8 |  | mdetuni.n | ⊢ ( 𝜑  →  𝑁  ∈  Fin ) | 
						
							| 9 |  | mdetuni.r | ⊢ ( 𝜑  →  𝑅  ∈  Ring ) | 
						
							| 10 |  | mdetuni.ff | ⊢ ( 𝜑  →  𝐷 : 𝐵 ⟶ 𝐾 ) | 
						
							| 11 |  | mdetuni.al | ⊢ ( 𝜑  →  ∀ 𝑥  ∈  𝐵 ∀ 𝑦  ∈  𝑁 ∀ 𝑧  ∈  𝑁 ( ( 𝑦  ≠  𝑧  ∧  ∀ 𝑤  ∈  𝑁 ( 𝑦 𝑥 𝑤 )  =  ( 𝑧 𝑥 𝑤 ) )  →  ( 𝐷 ‘ 𝑥 )  =   0  ) ) | 
						
							| 12 |  | mdetuni.li | ⊢ ( 𝜑  →  ∀ 𝑥  ∈  𝐵 ∀ 𝑦  ∈  𝐵 ∀ 𝑧  ∈  𝐵 ∀ 𝑤  ∈  𝑁 ( ( ( 𝑥  ↾  ( { 𝑤 }  ×  𝑁 ) )  =  ( ( 𝑦  ↾  ( { 𝑤 }  ×  𝑁 ) )  ∘f   +  ( 𝑧  ↾  ( { 𝑤 }  ×  𝑁 ) ) )  ∧  ( 𝑥  ↾  ( ( 𝑁  ∖  { 𝑤 } )  ×  𝑁 ) )  =  ( 𝑦  ↾  ( ( 𝑁  ∖  { 𝑤 } )  ×  𝑁 ) )  ∧  ( 𝑥  ↾  ( ( 𝑁  ∖  { 𝑤 } )  ×  𝑁 ) )  =  ( 𝑧  ↾  ( ( 𝑁  ∖  { 𝑤 } )  ×  𝑁 ) ) )  →  ( 𝐷 ‘ 𝑥 )  =  ( ( 𝐷 ‘ 𝑦 )  +  ( 𝐷 ‘ 𝑧 ) ) ) ) | 
						
							| 13 |  | mdetuni.sc | ⊢ ( 𝜑  →  ∀ 𝑥  ∈  𝐵 ∀ 𝑦  ∈  𝐾 ∀ 𝑧  ∈  𝐵 ∀ 𝑤  ∈  𝑁 ( ( ( 𝑥  ↾  ( { 𝑤 }  ×  𝑁 ) )  =  ( ( ( { 𝑤 }  ×  𝑁 )  ×  { 𝑦 } )  ∘f   ·  ( 𝑧  ↾  ( { 𝑤 }  ×  𝑁 ) ) )  ∧  ( 𝑥  ↾  ( ( 𝑁  ∖  { 𝑤 } )  ×  𝑁 ) )  =  ( 𝑧  ↾  ( ( 𝑁  ∖  { 𝑤 } )  ×  𝑁 ) ) )  →  ( 𝐷 ‘ 𝑥 )  =  ( 𝑦  ·  ( 𝐷 ‘ 𝑧 ) ) ) ) | 
						
							| 14 |  | mdetunilem5.ph | ⊢ ( 𝜓  →  𝜑 ) | 
						
							| 15 |  | mdetunilem5.e | ⊢ ( 𝜓  →  𝐸  ∈  𝑁 ) | 
						
							| 16 |  | mdetunilem5.fgh | ⊢ ( ( 𝜓  ∧  𝑎  ∈  𝑁  ∧  𝑏  ∈  𝑁 )  →  ( 𝐹  ∈  𝐾  ∧  𝐺  ∈  𝐾  ∧  𝐻  ∈  𝐾 ) ) | 
						
							| 17 | 14 8 | syl | ⊢ ( 𝜓  →  𝑁  ∈  Fin ) | 
						
							| 18 | 14 9 | syl | ⊢ ( 𝜓  →  𝑅  ∈  Ring ) | 
						
							| 19 | 18 | 3ad2ant1 | ⊢ ( ( 𝜓  ∧  𝑎  ∈  𝑁  ∧  𝑏  ∈  𝑁 )  →  𝑅  ∈  Ring ) | 
						
							| 20 | 16 | simp1d | ⊢ ( ( 𝜓  ∧  𝑎  ∈  𝑁  ∧  𝑏  ∈  𝑁 )  →  𝐹  ∈  𝐾 ) | 
						
							| 21 | 16 | simp2d | ⊢ ( ( 𝜓  ∧  𝑎  ∈  𝑁  ∧  𝑏  ∈  𝑁 )  →  𝐺  ∈  𝐾 ) | 
						
							| 22 | 3 6 | ringacl | ⊢ ( ( 𝑅  ∈  Ring  ∧  𝐹  ∈  𝐾  ∧  𝐺  ∈  𝐾 )  →  ( 𝐹  +  𝐺 )  ∈  𝐾 ) | 
						
							| 23 | 19 20 21 22 | syl3anc | ⊢ ( ( 𝜓  ∧  𝑎  ∈  𝑁  ∧  𝑏  ∈  𝑁 )  →  ( 𝐹  +  𝐺 )  ∈  𝐾 ) | 
						
							| 24 | 16 | simp3d | ⊢ ( ( 𝜓  ∧  𝑎  ∈  𝑁  ∧  𝑏  ∈  𝑁 )  →  𝐻  ∈  𝐾 ) | 
						
							| 25 | 23 24 | ifcld | ⊢ ( ( 𝜓  ∧  𝑎  ∈  𝑁  ∧  𝑏  ∈  𝑁 )  →  if ( 𝑎  =  𝐸 ,  ( 𝐹  +  𝐺 ) ,  𝐻 )  ∈  𝐾 ) | 
						
							| 26 | 1 3 2 17 18 25 | matbas2d | ⊢ ( 𝜓  →  ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  ( 𝐹  +  𝐺 ) ,  𝐻 ) )  ∈  𝐵 ) | 
						
							| 27 | 20 24 | ifcld | ⊢ ( ( 𝜓  ∧  𝑎  ∈  𝑁  ∧  𝑏  ∈  𝑁 )  →  if ( 𝑎  =  𝐸 ,  𝐹 ,  𝐻 )  ∈  𝐾 ) | 
						
							| 28 | 1 3 2 17 18 27 | matbas2d | ⊢ ( 𝜓  →  ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐹 ,  𝐻 ) )  ∈  𝐵 ) | 
						
							| 29 | 21 24 | ifcld | ⊢ ( ( 𝜓  ∧  𝑎  ∈  𝑁  ∧  𝑏  ∈  𝑁 )  →  if ( 𝑎  =  𝐸 ,  𝐺 ,  𝐻 )  ∈  𝐾 ) | 
						
							| 30 | 1 3 2 17 18 29 | matbas2d | ⊢ ( 𝜓  →  ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐺 ,  𝐻 ) )  ∈  𝐵 ) | 
						
							| 31 |  | snex | ⊢ { 𝐸 }  ∈  V | 
						
							| 32 | 31 | a1i | ⊢ ( 𝜓  →  { 𝐸 }  ∈  V ) | 
						
							| 33 | 15 | snssd | ⊢ ( 𝜓  →  { 𝐸 }  ⊆  𝑁 ) | 
						
							| 34 | 33 | 3ad2ant1 | ⊢ ( ( 𝜓  ∧  𝑎  ∈  { 𝐸 }  ∧  𝑏  ∈  𝑁 )  →  { 𝐸 }  ⊆  𝑁 ) | 
						
							| 35 |  | simp2 | ⊢ ( ( 𝜓  ∧  𝑎  ∈  { 𝐸 }  ∧  𝑏  ∈  𝑁 )  →  𝑎  ∈  { 𝐸 } ) | 
						
							| 36 | 34 35 | sseldd | ⊢ ( ( 𝜓  ∧  𝑎  ∈  { 𝐸 }  ∧  𝑏  ∈  𝑁 )  →  𝑎  ∈  𝑁 ) | 
						
							| 37 | 36 20 | syld3an2 | ⊢ ( ( 𝜓  ∧  𝑎  ∈  { 𝐸 }  ∧  𝑏  ∈  𝑁 )  →  𝐹  ∈  𝐾 ) | 
						
							| 38 | 36 21 | syld3an2 | ⊢ ( ( 𝜓  ∧  𝑎  ∈  { 𝐸 }  ∧  𝑏  ∈  𝑁 )  →  𝐺  ∈  𝐾 ) | 
						
							| 39 |  | eqidd | ⊢ ( 𝜓  →  ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  𝐹 )  =  ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  𝐹 ) ) | 
						
							| 40 |  | eqidd | ⊢ ( 𝜓  →  ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  𝐺 )  =  ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  𝐺 ) ) | 
						
							| 41 | 32 17 37 38 39 40 | offval22 | ⊢ ( 𝜓  →  ( ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  𝐹 )  ∘f   +  ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  𝐺 ) )  =  ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  ( 𝐹  +  𝐺 ) ) ) | 
						
							| 42 | 41 | eqcomd | ⊢ ( 𝜓  →  ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  ( 𝐹  +  𝐺 ) )  =  ( ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  𝐹 )  ∘f   +  ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  𝐺 ) ) ) | 
						
							| 43 |  | mposnif | ⊢ ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  ( 𝐹  +  𝐺 ) ,  𝐻 ) )  =  ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  ( 𝐹  +  𝐺 ) ) | 
						
							| 44 |  | mposnif | ⊢ ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐹 ,  𝐻 ) )  =  ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  𝐹 ) | 
						
							| 45 |  | mposnif | ⊢ ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐺 ,  𝐻 ) )  =  ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  𝐺 ) | 
						
							| 46 | 44 45 | oveq12i | ⊢ ( ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐹 ,  𝐻 ) )  ∘f   +  ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐺 ,  𝐻 ) ) )  =  ( ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  𝐹 )  ∘f   +  ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  𝐺 ) ) | 
						
							| 47 | 42 43 46 | 3eqtr4g | ⊢ ( 𝜓  →  ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  ( 𝐹  +  𝐺 ) ,  𝐻 ) )  =  ( ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐹 ,  𝐻 ) )  ∘f   +  ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐺 ,  𝐻 ) ) ) ) | 
						
							| 48 |  | ssid | ⊢ 𝑁  ⊆  𝑁 | 
						
							| 49 |  | resmpo | ⊢ ( ( { 𝐸 }  ⊆  𝑁  ∧  𝑁  ⊆  𝑁 )  →  ( ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  ( 𝐹  +  𝐺 ) ,  𝐻 ) )  ↾  ( { 𝐸 }  ×  𝑁 ) )  =  ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  ( 𝐹  +  𝐺 ) ,  𝐻 ) ) ) | 
						
							| 50 | 33 48 49 | sylancl | ⊢ ( 𝜓  →  ( ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  ( 𝐹  +  𝐺 ) ,  𝐻 ) )  ↾  ( { 𝐸 }  ×  𝑁 ) )  =  ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  ( 𝐹  +  𝐺 ) ,  𝐻 ) ) ) | 
						
							| 51 |  | resmpo | ⊢ ( ( { 𝐸 }  ⊆  𝑁  ∧  𝑁  ⊆  𝑁 )  →  ( ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐹 ,  𝐻 ) )  ↾  ( { 𝐸 }  ×  𝑁 ) )  =  ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐹 ,  𝐻 ) ) ) | 
						
							| 52 | 33 48 51 | sylancl | ⊢ ( 𝜓  →  ( ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐹 ,  𝐻 ) )  ↾  ( { 𝐸 }  ×  𝑁 ) )  =  ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐹 ,  𝐻 ) ) ) | 
						
							| 53 |  | resmpo | ⊢ ( ( { 𝐸 }  ⊆  𝑁  ∧  𝑁  ⊆  𝑁 )  →  ( ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐺 ,  𝐻 ) )  ↾  ( { 𝐸 }  ×  𝑁 ) )  =  ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐺 ,  𝐻 ) ) ) | 
						
							| 54 | 33 48 53 | sylancl | ⊢ ( 𝜓  →  ( ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐺 ,  𝐻 ) )  ↾  ( { 𝐸 }  ×  𝑁 ) )  =  ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐺 ,  𝐻 ) ) ) | 
						
							| 55 | 52 54 | oveq12d | ⊢ ( 𝜓  →  ( ( ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐹 ,  𝐻 ) )  ↾  ( { 𝐸 }  ×  𝑁 ) )  ∘f   +  ( ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐺 ,  𝐻 ) )  ↾  ( { 𝐸 }  ×  𝑁 ) ) )  =  ( ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐹 ,  𝐻 ) )  ∘f   +  ( 𝑎  ∈  { 𝐸 } ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐺 ,  𝐻 ) ) ) ) | 
						
							| 56 | 47 50 55 | 3eqtr4d | ⊢ ( 𝜓  →  ( ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  ( 𝐹  +  𝐺 ) ,  𝐻 ) )  ↾  ( { 𝐸 }  ×  𝑁 ) )  =  ( ( ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐹 ,  𝐻 ) )  ↾  ( { 𝐸 }  ×  𝑁 ) )  ∘f   +  ( ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐺 ,  𝐻 ) )  ↾  ( { 𝐸 }  ×  𝑁 ) ) ) ) | 
						
							| 57 |  | eldifsni | ⊢ ( 𝑎  ∈  ( 𝑁  ∖  { 𝐸 } )  →  𝑎  ≠  𝐸 ) | 
						
							| 58 | 57 | 3ad2ant2 | ⊢ ( ( 𝜓  ∧  𝑎  ∈  ( 𝑁  ∖  { 𝐸 } )  ∧  𝑏  ∈  𝑁 )  →  𝑎  ≠  𝐸 ) | 
						
							| 59 | 58 | neneqd | ⊢ ( ( 𝜓  ∧  𝑎  ∈  ( 𝑁  ∖  { 𝐸 } )  ∧  𝑏  ∈  𝑁 )  →  ¬  𝑎  =  𝐸 ) | 
						
							| 60 |  | iffalse | ⊢ ( ¬  𝑎  =  𝐸  →  if ( 𝑎  =  𝐸 ,  ( 𝐹  +  𝐺 ) ,  𝐻 )  =  𝐻 ) | 
						
							| 61 |  | iffalse | ⊢ ( ¬  𝑎  =  𝐸  →  if ( 𝑎  =  𝐸 ,  𝐹 ,  𝐻 )  =  𝐻 ) | 
						
							| 62 | 60 61 | eqtr4d | ⊢ ( ¬  𝑎  =  𝐸  →  if ( 𝑎  =  𝐸 ,  ( 𝐹  +  𝐺 ) ,  𝐻 )  =  if ( 𝑎  =  𝐸 ,  𝐹 ,  𝐻 ) ) | 
						
							| 63 | 59 62 | syl | ⊢ ( ( 𝜓  ∧  𝑎  ∈  ( 𝑁  ∖  { 𝐸 } )  ∧  𝑏  ∈  𝑁 )  →  if ( 𝑎  =  𝐸 ,  ( 𝐹  +  𝐺 ) ,  𝐻 )  =  if ( 𝑎  =  𝐸 ,  𝐹 ,  𝐻 ) ) | 
						
							| 64 | 63 | mpoeq3dva | ⊢ ( 𝜓  →  ( 𝑎  ∈  ( 𝑁  ∖  { 𝐸 } ) ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  ( 𝐹  +  𝐺 ) ,  𝐻 ) )  =  ( 𝑎  ∈  ( 𝑁  ∖  { 𝐸 } ) ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐹 ,  𝐻 ) ) ) | 
						
							| 65 |  | difss | ⊢ ( 𝑁  ∖  { 𝐸 } )  ⊆  𝑁 | 
						
							| 66 |  | resmpo | ⊢ ( ( ( 𝑁  ∖  { 𝐸 } )  ⊆  𝑁  ∧  𝑁  ⊆  𝑁 )  →  ( ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  ( 𝐹  +  𝐺 ) ,  𝐻 ) )  ↾  ( ( 𝑁  ∖  { 𝐸 } )  ×  𝑁 ) )  =  ( 𝑎  ∈  ( 𝑁  ∖  { 𝐸 } ) ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  ( 𝐹  +  𝐺 ) ,  𝐻 ) ) ) | 
						
							| 67 | 65 48 66 | mp2an | ⊢ ( ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  ( 𝐹  +  𝐺 ) ,  𝐻 ) )  ↾  ( ( 𝑁  ∖  { 𝐸 } )  ×  𝑁 ) )  =  ( 𝑎  ∈  ( 𝑁  ∖  { 𝐸 } ) ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  ( 𝐹  +  𝐺 ) ,  𝐻 ) ) | 
						
							| 68 |  | resmpo | ⊢ ( ( ( 𝑁  ∖  { 𝐸 } )  ⊆  𝑁  ∧  𝑁  ⊆  𝑁 )  →  ( ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐹 ,  𝐻 ) )  ↾  ( ( 𝑁  ∖  { 𝐸 } )  ×  𝑁 ) )  =  ( 𝑎  ∈  ( 𝑁  ∖  { 𝐸 } ) ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐹 ,  𝐻 ) ) ) | 
						
							| 69 | 65 48 68 | mp2an | ⊢ ( ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐹 ,  𝐻 ) )  ↾  ( ( 𝑁  ∖  { 𝐸 } )  ×  𝑁 ) )  =  ( 𝑎  ∈  ( 𝑁  ∖  { 𝐸 } ) ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐹 ,  𝐻 ) ) | 
						
							| 70 | 64 67 69 | 3eqtr4g | ⊢ ( 𝜓  →  ( ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  ( 𝐹  +  𝐺 ) ,  𝐻 ) )  ↾  ( ( 𝑁  ∖  { 𝐸 } )  ×  𝑁 ) )  =  ( ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐹 ,  𝐻 ) )  ↾  ( ( 𝑁  ∖  { 𝐸 } )  ×  𝑁 ) ) ) | 
						
							| 71 |  | iffalse | ⊢ ( ¬  𝑎  =  𝐸  →  if ( 𝑎  =  𝐸 ,  𝐺 ,  𝐻 )  =  𝐻 ) | 
						
							| 72 | 60 71 | eqtr4d | ⊢ ( ¬  𝑎  =  𝐸  →  if ( 𝑎  =  𝐸 ,  ( 𝐹  +  𝐺 ) ,  𝐻 )  =  if ( 𝑎  =  𝐸 ,  𝐺 ,  𝐻 ) ) | 
						
							| 73 | 59 72 | syl | ⊢ ( ( 𝜓  ∧  𝑎  ∈  ( 𝑁  ∖  { 𝐸 } )  ∧  𝑏  ∈  𝑁 )  →  if ( 𝑎  =  𝐸 ,  ( 𝐹  +  𝐺 ) ,  𝐻 )  =  if ( 𝑎  =  𝐸 ,  𝐺 ,  𝐻 ) ) | 
						
							| 74 | 73 | mpoeq3dva | ⊢ ( 𝜓  →  ( 𝑎  ∈  ( 𝑁  ∖  { 𝐸 } ) ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  ( 𝐹  +  𝐺 ) ,  𝐻 ) )  =  ( 𝑎  ∈  ( 𝑁  ∖  { 𝐸 } ) ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐺 ,  𝐻 ) ) ) | 
						
							| 75 |  | resmpo | ⊢ ( ( ( 𝑁  ∖  { 𝐸 } )  ⊆  𝑁  ∧  𝑁  ⊆  𝑁 )  →  ( ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐺 ,  𝐻 ) )  ↾  ( ( 𝑁  ∖  { 𝐸 } )  ×  𝑁 ) )  =  ( 𝑎  ∈  ( 𝑁  ∖  { 𝐸 } ) ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐺 ,  𝐻 ) ) ) | 
						
							| 76 | 65 48 75 | mp2an | ⊢ ( ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐺 ,  𝐻 ) )  ↾  ( ( 𝑁  ∖  { 𝐸 } )  ×  𝑁 ) )  =  ( 𝑎  ∈  ( 𝑁  ∖  { 𝐸 } ) ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐺 ,  𝐻 ) ) | 
						
							| 77 | 74 67 76 | 3eqtr4g | ⊢ ( 𝜓  →  ( ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  ( 𝐹  +  𝐺 ) ,  𝐻 ) )  ↾  ( ( 𝑁  ∖  { 𝐸 } )  ×  𝑁 ) )  =  ( ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐺 ,  𝐻 ) )  ↾  ( ( 𝑁  ∖  { 𝐸 } )  ×  𝑁 ) ) ) | 
						
							| 78 | 1 2 3 4 5 6 7 8 9 10 11 12 13 | mdetunilem3 | ⊢ ( ( ( 𝜑  ∧  ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  ( 𝐹  +  𝐺 ) ,  𝐻 ) )  ∈  𝐵  ∧  ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐹 ,  𝐻 ) )  ∈  𝐵 )  ∧  ( ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐺 ,  𝐻 ) )  ∈  𝐵  ∧  𝐸  ∈  𝑁  ∧  ( ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  ( 𝐹  +  𝐺 ) ,  𝐻 ) )  ↾  ( { 𝐸 }  ×  𝑁 ) )  =  ( ( ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐹 ,  𝐻 ) )  ↾  ( { 𝐸 }  ×  𝑁 ) )  ∘f   +  ( ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐺 ,  𝐻 ) )  ↾  ( { 𝐸 }  ×  𝑁 ) ) ) )  ∧  ( ( ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  ( 𝐹  +  𝐺 ) ,  𝐻 ) )  ↾  ( ( 𝑁  ∖  { 𝐸 } )  ×  𝑁 ) )  =  ( ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐹 ,  𝐻 ) )  ↾  ( ( 𝑁  ∖  { 𝐸 } )  ×  𝑁 ) )  ∧  ( ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  ( 𝐹  +  𝐺 ) ,  𝐻 ) )  ↾  ( ( 𝑁  ∖  { 𝐸 } )  ×  𝑁 ) )  =  ( ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐺 ,  𝐻 ) )  ↾  ( ( 𝑁  ∖  { 𝐸 } )  ×  𝑁 ) ) ) )  →  ( 𝐷 ‘ ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  ( 𝐹  +  𝐺 ) ,  𝐻 ) ) )  =  ( ( 𝐷 ‘ ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐹 ,  𝐻 ) ) )  +  ( 𝐷 ‘ ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐺 ,  𝐻 ) ) ) ) ) | 
						
							| 79 | 14 26 28 30 15 56 70 77 78 | syl332anc | ⊢ ( 𝜓  →  ( 𝐷 ‘ ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  ( 𝐹  +  𝐺 ) ,  𝐻 ) ) )  =  ( ( 𝐷 ‘ ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐹 ,  𝐻 ) ) )  +  ( 𝐷 ‘ ( 𝑎  ∈  𝑁 ,  𝑏  ∈  𝑁  ↦  if ( 𝑎  =  𝐸 ,  𝐺 ,  𝐻 ) ) ) ) ) |