| Step | Hyp | Ref | Expression | 
						
							| 1 |  | dochsncom.h | ⊢ 𝐻  =  ( LHyp ‘ 𝐾 ) | 
						
							| 2 |  | dochsncom.o | ⊢  ⊥   =  ( ( ocH ‘ 𝐾 ) ‘ 𝑊 ) | 
						
							| 3 |  | dochsncom.u | ⊢ 𝑈  =  ( ( DVecH ‘ 𝐾 ) ‘ 𝑊 ) | 
						
							| 4 |  | dochsncom.v | ⊢ 𝑉  =  ( Base ‘ 𝑈 ) | 
						
							| 5 |  | dochsncom.k | ⊢ ( 𝜑  →  ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 ) ) | 
						
							| 6 |  | dochsncom.x | ⊢ ( 𝜑  →  𝑋  ∈  𝑉 ) | 
						
							| 7 |  | dochsncom.y | ⊢ ( 𝜑  →  𝑌  ∈  𝑉 ) | 
						
							| 8 |  | eqid | ⊢ ( ( DIsoH ‘ 𝐾 ) ‘ 𝑊 )  =  ( ( DIsoH ‘ 𝐾 ) ‘ 𝑊 ) | 
						
							| 9 |  | eqid | ⊢ ( LSpan ‘ 𝑈 )  =  ( LSpan ‘ 𝑈 ) | 
						
							| 10 | 1 3 4 9 8 | dihlsprn | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑋  ∈  𝑉 )  →  ( ( LSpan ‘ 𝑈 ) ‘ { 𝑋 } )  ∈  ran  ( ( DIsoH ‘ 𝐾 ) ‘ 𝑊 ) ) | 
						
							| 11 | 5 6 10 | syl2anc | ⊢ ( 𝜑  →  ( ( LSpan ‘ 𝑈 ) ‘ { 𝑋 } )  ∈  ran  ( ( DIsoH ‘ 𝐾 ) ‘ 𝑊 ) ) | 
						
							| 12 | 1 3 4 9 8 | dihlsprn | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑌  ∈  𝑉 )  →  ( ( LSpan ‘ 𝑈 ) ‘ { 𝑌 } )  ∈  ran  ( ( DIsoH ‘ 𝐾 ) ‘ 𝑊 ) ) | 
						
							| 13 | 5 7 12 | syl2anc | ⊢ ( 𝜑  →  ( ( LSpan ‘ 𝑈 ) ‘ { 𝑌 } )  ∈  ran  ( ( DIsoH ‘ 𝐾 ) ‘ 𝑊 ) ) | 
						
							| 14 | 1 8 2 5 11 13 | dochord3 | ⊢ ( 𝜑  →  ( ( ( LSpan ‘ 𝑈 ) ‘ { 𝑋 } )  ⊆  (  ⊥  ‘ ( ( LSpan ‘ 𝑈 ) ‘ { 𝑌 } ) )  ↔  ( ( LSpan ‘ 𝑈 ) ‘ { 𝑌 } )  ⊆  (  ⊥  ‘ ( ( LSpan ‘ 𝑈 ) ‘ { 𝑋 } ) ) ) ) | 
						
							| 15 | 7 | snssd | ⊢ ( 𝜑  →  { 𝑌 }  ⊆  𝑉 ) | 
						
							| 16 | 1 3 2 4 9 5 15 | dochocsp | ⊢ ( 𝜑  →  (  ⊥  ‘ ( ( LSpan ‘ 𝑈 ) ‘ { 𝑌 } ) )  =  (  ⊥  ‘ { 𝑌 } ) ) | 
						
							| 17 | 16 | sseq2d | ⊢ ( 𝜑  →  ( ( ( LSpan ‘ 𝑈 ) ‘ { 𝑋 } )  ⊆  (  ⊥  ‘ ( ( LSpan ‘ 𝑈 ) ‘ { 𝑌 } ) )  ↔  ( ( LSpan ‘ 𝑈 ) ‘ { 𝑋 } )  ⊆  (  ⊥  ‘ { 𝑌 } ) ) ) | 
						
							| 18 | 6 | snssd | ⊢ ( 𝜑  →  { 𝑋 }  ⊆  𝑉 ) | 
						
							| 19 | 1 3 2 4 9 5 18 | dochocsp | ⊢ ( 𝜑  →  (  ⊥  ‘ ( ( LSpan ‘ 𝑈 ) ‘ { 𝑋 } ) )  =  (  ⊥  ‘ { 𝑋 } ) ) | 
						
							| 20 | 19 | sseq2d | ⊢ ( 𝜑  →  ( ( ( LSpan ‘ 𝑈 ) ‘ { 𝑌 } )  ⊆  (  ⊥  ‘ ( ( LSpan ‘ 𝑈 ) ‘ { 𝑋 } ) )  ↔  ( ( LSpan ‘ 𝑈 ) ‘ { 𝑌 } )  ⊆  (  ⊥  ‘ { 𝑋 } ) ) ) | 
						
							| 21 | 14 17 20 | 3bitr3d | ⊢ ( 𝜑  →  ( ( ( LSpan ‘ 𝑈 ) ‘ { 𝑋 } )  ⊆  (  ⊥  ‘ { 𝑌 } )  ↔  ( ( LSpan ‘ 𝑈 ) ‘ { 𝑌 } )  ⊆  (  ⊥  ‘ { 𝑋 } ) ) ) | 
						
							| 22 |  | eqid | ⊢ ( LSubSp ‘ 𝑈 )  =  ( LSubSp ‘ 𝑈 ) | 
						
							| 23 | 1 3 5 | dvhlmod | ⊢ ( 𝜑  →  𝑈  ∈  LMod ) | 
						
							| 24 | 1 3 4 22 2 | dochlss | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  { 𝑌 }  ⊆  𝑉 )  →  (  ⊥  ‘ { 𝑌 } )  ∈  ( LSubSp ‘ 𝑈 ) ) | 
						
							| 25 | 5 15 24 | syl2anc | ⊢ ( 𝜑  →  (  ⊥  ‘ { 𝑌 } )  ∈  ( LSubSp ‘ 𝑈 ) ) | 
						
							| 26 | 4 22 9 23 25 6 | ellspsn5b | ⊢ ( 𝜑  →  ( 𝑋  ∈  (  ⊥  ‘ { 𝑌 } )  ↔  ( ( LSpan ‘ 𝑈 ) ‘ { 𝑋 } )  ⊆  (  ⊥  ‘ { 𝑌 } ) ) ) | 
						
							| 27 | 1 3 4 22 2 | dochlss | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  { 𝑋 }  ⊆  𝑉 )  →  (  ⊥  ‘ { 𝑋 } )  ∈  ( LSubSp ‘ 𝑈 ) ) | 
						
							| 28 | 5 18 27 | syl2anc | ⊢ ( 𝜑  →  (  ⊥  ‘ { 𝑋 } )  ∈  ( LSubSp ‘ 𝑈 ) ) | 
						
							| 29 | 4 22 9 23 28 7 | ellspsn5b | ⊢ ( 𝜑  →  ( 𝑌  ∈  (  ⊥  ‘ { 𝑋 } )  ↔  ( ( LSpan ‘ 𝑈 ) ‘ { 𝑌 } )  ⊆  (  ⊥  ‘ { 𝑋 } ) ) ) | 
						
							| 30 | 21 26 29 | 3bitr4d | ⊢ ( 𝜑  →  ( 𝑋  ∈  (  ⊥  ‘ { 𝑌 } )  ↔  𝑌  ∈  (  ⊥  ‘ { 𝑋 } ) ) ) |