| Step | Hyp | Ref | Expression | 
						
							| 1 |  | diaoc.j | ⊢  ∨   =  ( join ‘ 𝐾 ) | 
						
							| 2 |  | diaoc.m | ⊢  ∧   =  ( meet ‘ 𝐾 ) | 
						
							| 3 |  | diaoc.o | ⊢  ⊥   =  ( oc ‘ 𝐾 ) | 
						
							| 4 |  | diaoc.h | ⊢ 𝐻  =  ( LHyp ‘ 𝐾 ) | 
						
							| 5 |  | diaoc.t | ⊢ 𝑇  =  ( ( LTrn ‘ 𝐾 ) ‘ 𝑊 ) | 
						
							| 6 |  | diaoc.i | ⊢ 𝐼  =  ( ( DIsoA ‘ 𝐾 ) ‘ 𝑊 ) | 
						
							| 7 |  | diaoc.n | ⊢ 𝑁  =  ( ( ocA ‘ 𝐾 ) ‘ 𝑊 ) | 
						
							| 8 |  | simpl | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑋  ∈  dom  𝐼 )  →  ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 ) ) | 
						
							| 9 |  | eqid | ⊢ ( Base ‘ 𝐾 )  =  ( Base ‘ 𝐾 ) | 
						
							| 10 | 9 4 6 | diadmclN | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑋  ∈  dom  𝐼 )  →  𝑋  ∈  ( Base ‘ 𝐾 ) ) | 
						
							| 11 |  | eqid | ⊢ ( le ‘ 𝐾 )  =  ( le ‘ 𝐾 ) | 
						
							| 12 | 11 4 6 | diadmleN | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑋  ∈  dom  𝐼 )  →  𝑋 ( le ‘ 𝐾 ) 𝑊 ) | 
						
							| 13 | 9 11 4 5 6 | diass | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  ( 𝑋  ∈  ( Base ‘ 𝐾 )  ∧  𝑋 ( le ‘ 𝐾 ) 𝑊 ) )  →  ( 𝐼 ‘ 𝑋 )  ⊆  𝑇 ) | 
						
							| 14 | 8 10 12 13 | syl12anc | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑋  ∈  dom  𝐼 )  →  ( 𝐼 ‘ 𝑋 )  ⊆  𝑇 ) | 
						
							| 15 | 1 2 3 4 5 6 7 | docavalN | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  ( 𝐼 ‘ 𝑋 )  ⊆  𝑇 )  →  ( 𝑁 ‘ ( 𝐼 ‘ 𝑋 ) )  =  ( 𝐼 ‘ ( ( (  ⊥  ‘ ( ◡ 𝐼 ‘ ∩  { 𝑧  ∈  ran  𝐼  ∣  ( 𝐼 ‘ 𝑋 )  ⊆  𝑧 } ) )  ∨  (  ⊥  ‘ 𝑊 ) )  ∧  𝑊 ) ) ) | 
						
							| 16 | 14 15 | syldan | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑋  ∈  dom  𝐼 )  →  ( 𝑁 ‘ ( 𝐼 ‘ 𝑋 ) )  =  ( 𝐼 ‘ ( ( (  ⊥  ‘ ( ◡ 𝐼 ‘ ∩  { 𝑧  ∈  ran  𝐼  ∣  ( 𝐼 ‘ 𝑋 )  ⊆  𝑧 } ) )  ∨  (  ⊥  ‘ 𝑊 ) )  ∧  𝑊 ) ) ) | 
						
							| 17 | 4 6 | diaclN | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑋  ∈  dom  𝐼 )  →  ( 𝐼 ‘ 𝑋 )  ∈  ran  𝐼 ) | 
						
							| 18 |  | intmin | ⊢ ( ( 𝐼 ‘ 𝑋 )  ∈  ran  𝐼  →  ∩  { 𝑧  ∈  ran  𝐼  ∣  ( 𝐼 ‘ 𝑋 )  ⊆  𝑧 }  =  ( 𝐼 ‘ 𝑋 ) ) | 
						
							| 19 | 17 18 | syl | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑋  ∈  dom  𝐼 )  →  ∩  { 𝑧  ∈  ran  𝐼  ∣  ( 𝐼 ‘ 𝑋 )  ⊆  𝑧 }  =  ( 𝐼 ‘ 𝑋 ) ) | 
						
							| 20 | 19 | fveq2d | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑋  ∈  dom  𝐼 )  →  ( ◡ 𝐼 ‘ ∩  { 𝑧  ∈  ran  𝐼  ∣  ( 𝐼 ‘ 𝑋 )  ⊆  𝑧 } )  =  ( ◡ 𝐼 ‘ ( 𝐼 ‘ 𝑋 ) ) ) | 
						
							| 21 | 4 6 | diaf11N | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  →  𝐼 : dom  𝐼 –1-1-onto→ ran  𝐼 ) | 
						
							| 22 |  | f1ocnvfv1 | ⊢ ( ( 𝐼 : dom  𝐼 –1-1-onto→ ran  𝐼  ∧  𝑋  ∈  dom  𝐼 )  →  ( ◡ 𝐼 ‘ ( 𝐼 ‘ 𝑋 ) )  =  𝑋 ) | 
						
							| 23 | 21 22 | sylan | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑋  ∈  dom  𝐼 )  →  ( ◡ 𝐼 ‘ ( 𝐼 ‘ 𝑋 ) )  =  𝑋 ) | 
						
							| 24 | 20 23 | eqtrd | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑋  ∈  dom  𝐼 )  →  ( ◡ 𝐼 ‘ ∩  { 𝑧  ∈  ran  𝐼  ∣  ( 𝐼 ‘ 𝑋 )  ⊆  𝑧 } )  =  𝑋 ) | 
						
							| 25 | 24 | fveq2d | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑋  ∈  dom  𝐼 )  →  (  ⊥  ‘ ( ◡ 𝐼 ‘ ∩  { 𝑧  ∈  ran  𝐼  ∣  ( 𝐼 ‘ 𝑋 )  ⊆  𝑧 } ) )  =  (  ⊥  ‘ 𝑋 ) ) | 
						
							| 26 | 25 | oveq1d | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑋  ∈  dom  𝐼 )  →  ( (  ⊥  ‘ ( ◡ 𝐼 ‘ ∩  { 𝑧  ∈  ran  𝐼  ∣  ( 𝐼 ‘ 𝑋 )  ⊆  𝑧 } ) )  ∨  (  ⊥  ‘ 𝑊 ) )  =  ( (  ⊥  ‘ 𝑋 )  ∨  (  ⊥  ‘ 𝑊 ) ) ) | 
						
							| 27 | 26 | fvoveq1d | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑋  ∈  dom  𝐼 )  →  ( 𝐼 ‘ ( ( (  ⊥  ‘ ( ◡ 𝐼 ‘ ∩  { 𝑧  ∈  ran  𝐼  ∣  ( 𝐼 ‘ 𝑋 )  ⊆  𝑧 } ) )  ∨  (  ⊥  ‘ 𝑊 ) )  ∧  𝑊 ) )  =  ( 𝐼 ‘ ( ( (  ⊥  ‘ 𝑋 )  ∨  (  ⊥  ‘ 𝑊 ) )  ∧  𝑊 ) ) ) | 
						
							| 28 | 16 27 | eqtr2d | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑋  ∈  dom  𝐼 )  →  ( 𝐼 ‘ ( ( (  ⊥  ‘ 𝑋 )  ∨  (  ⊥  ‘ 𝑊 ) )  ∧  𝑊 ) )  =  ( 𝑁 ‘ ( 𝐼 ‘ 𝑋 ) ) ) |