| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ocvz.v | ⊢ 𝑉  =  ( Base ‘ 𝑊 ) | 
						
							| 2 |  | ocvz.o | ⊢  ⊥   =  ( ocv ‘ 𝑊 ) | 
						
							| 3 |  | ocvz.z | ⊢  0   =  ( 0g ‘ 𝑊 ) | 
						
							| 4 |  | phllmod | ⊢ ( 𝑊  ∈  PreHil  →  𝑊  ∈  LMod ) | 
						
							| 5 |  | eqid | ⊢ ( LSpan ‘ 𝑊 )  =  ( LSpan ‘ 𝑊 ) | 
						
							| 6 | 3 5 | lsp0 | ⊢ ( 𝑊  ∈  LMod  →  ( ( LSpan ‘ 𝑊 ) ‘ ∅ )  =  {  0  } ) | 
						
							| 7 | 4 6 | syl | ⊢ ( 𝑊  ∈  PreHil  →  ( ( LSpan ‘ 𝑊 ) ‘ ∅ )  =  {  0  } ) | 
						
							| 8 | 7 | fveq2d | ⊢ ( 𝑊  ∈  PreHil  →  (  ⊥  ‘ ( ( LSpan ‘ 𝑊 ) ‘ ∅ ) )  =  (  ⊥  ‘ {  0  } ) ) | 
						
							| 9 |  | 0ss | ⊢ ∅  ⊆  𝑉 | 
						
							| 10 | 1 2 5 | ocvlsp | ⊢ ( ( 𝑊  ∈  PreHil  ∧  ∅  ⊆  𝑉 )  →  (  ⊥  ‘ ( ( LSpan ‘ 𝑊 ) ‘ ∅ ) )  =  (  ⊥  ‘ ∅ ) ) | 
						
							| 11 | 9 10 | mpan2 | ⊢ ( 𝑊  ∈  PreHil  →  (  ⊥  ‘ ( ( LSpan ‘ 𝑊 ) ‘ ∅ ) )  =  (  ⊥  ‘ ∅ ) ) | 
						
							| 12 | 1 2 | ocv0 | ⊢ (  ⊥  ‘ ∅ )  =  𝑉 | 
						
							| 13 | 11 12 | eqtrdi | ⊢ ( 𝑊  ∈  PreHil  →  (  ⊥  ‘ ( ( LSpan ‘ 𝑊 ) ‘ ∅ ) )  =  𝑉 ) | 
						
							| 14 | 8 13 | eqtr3d | ⊢ ( 𝑊  ∈  PreHil  →  (  ⊥  ‘ {  0  } )  =  𝑉 ) |