| Step | Hyp | Ref | Expression | 
						
							| 1 |  | djhexmid.h | ⊢ 𝐻  =  ( LHyp ‘ 𝐾 ) | 
						
							| 2 |  | djhexmid.u | ⊢ 𝑈  =  ( ( DVecH ‘ 𝐾 ) ‘ 𝑊 ) | 
						
							| 3 |  | djhexmid.v | ⊢ 𝑉  =  ( Base ‘ 𝑈 ) | 
						
							| 4 |  | djhexmid.o | ⊢  ⊥   =  ( ( ocH ‘ 𝐾 ) ‘ 𝑊 ) | 
						
							| 5 |  | djhexmid.j | ⊢  ∨   =  ( ( joinH ‘ 𝐾 ) ‘ 𝑊 ) | 
						
							| 6 |  | simpl | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑋  ⊆  𝑉 )  →  ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 ) ) | 
						
							| 7 |  | simpr | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑋  ⊆  𝑉 )  →  𝑋  ⊆  𝑉 ) | 
						
							| 8 | 1 2 3 4 | dochssv | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑋  ⊆  𝑉 )  →  (  ⊥  ‘ 𝑋 )  ⊆  𝑉 ) | 
						
							| 9 | 1 2 3 4 5 | djhval | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  ( 𝑋  ⊆  𝑉  ∧  (  ⊥  ‘ 𝑋 )  ⊆  𝑉 ) )  →  ( 𝑋  ∨  (  ⊥  ‘ 𝑋 ) )  =  (  ⊥  ‘ ( (  ⊥  ‘ 𝑋 )  ∩  (  ⊥  ‘ (  ⊥  ‘ 𝑋 ) ) ) ) ) | 
						
							| 10 | 6 7 8 9 | syl12anc | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑋  ⊆  𝑉 )  →  ( 𝑋  ∨  (  ⊥  ‘ 𝑋 ) )  =  (  ⊥  ‘ ( (  ⊥  ‘ 𝑋 )  ∩  (  ⊥  ‘ (  ⊥  ‘ 𝑋 ) ) ) ) ) | 
						
							| 11 |  | eqid | ⊢ ( LSubSp ‘ 𝑈 )  =  ( LSubSp ‘ 𝑈 ) | 
						
							| 12 | 1 2 3 11 4 | dochlss | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑋  ⊆  𝑉 )  →  (  ⊥  ‘ 𝑋 )  ∈  ( LSubSp ‘ 𝑈 ) ) | 
						
							| 13 |  | eqid | ⊢ ( 0g ‘ 𝑈 )  =  ( 0g ‘ 𝑈 ) | 
						
							| 14 | 1 2 11 13 4 | dochnoncon | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  (  ⊥  ‘ 𝑋 )  ∈  ( LSubSp ‘ 𝑈 ) )  →  ( (  ⊥  ‘ 𝑋 )  ∩  (  ⊥  ‘ (  ⊥  ‘ 𝑋 ) ) )  =  { ( 0g ‘ 𝑈 ) } ) | 
						
							| 15 | 12 14 | syldan | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑋  ⊆  𝑉 )  →  ( (  ⊥  ‘ 𝑋 )  ∩  (  ⊥  ‘ (  ⊥  ‘ 𝑋 ) ) )  =  { ( 0g ‘ 𝑈 ) } ) | 
						
							| 16 | 1 2 4 3 13 | doch1 | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  →  (  ⊥  ‘ 𝑉 )  =  { ( 0g ‘ 𝑈 ) } ) | 
						
							| 17 | 16 | adantr | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑋  ⊆  𝑉 )  →  (  ⊥  ‘ 𝑉 )  =  { ( 0g ‘ 𝑈 ) } ) | 
						
							| 18 | 15 17 | eqtr4d | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑋  ⊆  𝑉 )  →  ( (  ⊥  ‘ 𝑋 )  ∩  (  ⊥  ‘ (  ⊥  ‘ 𝑋 ) ) )  =  (  ⊥  ‘ 𝑉 ) ) | 
						
							| 19 | 18 | fveq2d | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑋  ⊆  𝑉 )  →  (  ⊥  ‘ ( (  ⊥  ‘ 𝑋 )  ∩  (  ⊥  ‘ (  ⊥  ‘ 𝑋 ) ) ) )  =  (  ⊥  ‘ (  ⊥  ‘ 𝑉 ) ) ) | 
						
							| 20 |  | eqid | ⊢ ( ( DIsoH ‘ 𝐾 ) ‘ 𝑊 )  =  ( ( DIsoH ‘ 𝐾 ) ‘ 𝑊 ) | 
						
							| 21 | 1 20 2 3 | dih1rn | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  →  𝑉  ∈  ran  ( ( DIsoH ‘ 𝐾 ) ‘ 𝑊 ) ) | 
						
							| 22 | 21 | adantr | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑋  ⊆  𝑉 )  →  𝑉  ∈  ran  ( ( DIsoH ‘ 𝐾 ) ‘ 𝑊 ) ) | 
						
							| 23 | 1 20 4 | dochoc | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑉  ∈  ran  ( ( DIsoH ‘ 𝐾 ) ‘ 𝑊 ) )  →  (  ⊥  ‘ (  ⊥  ‘ 𝑉 ) )  =  𝑉 ) | 
						
							| 24 | 22 23 | syldan | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑋  ⊆  𝑉 )  →  (  ⊥  ‘ (  ⊥  ‘ 𝑉 ) )  =  𝑉 ) | 
						
							| 25 | 10 19 24 | 3eqtrd | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑋  ⊆  𝑉 )  →  ( 𝑋  ∨  (  ⊥  ‘ 𝑋 ) )  =  𝑉 ) |