| Step | Hyp | Ref | Expression | 
						
							| 1 |  | lbsss.v | ⊢ 𝑉  =  ( Base ‘ 𝑊 ) | 
						
							| 2 |  | lbsss.j | ⊢ 𝐽  =  ( LBasis ‘ 𝑊 ) | 
						
							| 3 |  | lbssp.n | ⊢ 𝑁  =  ( LSpan ‘ 𝑊 ) | 
						
							| 4 |  | elfvdm | ⊢ ( 𝐵  ∈  ( LBasis ‘ 𝑊 )  →  𝑊  ∈  dom  LBasis ) | 
						
							| 5 | 4 2 | eleq2s | ⊢ ( 𝐵  ∈  𝐽  →  𝑊  ∈  dom  LBasis ) | 
						
							| 6 |  | eqid | ⊢ ( Scalar ‘ 𝑊 )  =  ( Scalar ‘ 𝑊 ) | 
						
							| 7 |  | eqid | ⊢ (  ·𝑠  ‘ 𝑊 )  =  (  ·𝑠  ‘ 𝑊 ) | 
						
							| 8 |  | eqid | ⊢ ( Base ‘ ( Scalar ‘ 𝑊 ) )  =  ( Base ‘ ( Scalar ‘ 𝑊 ) ) | 
						
							| 9 |  | eqid | ⊢ ( 0g ‘ ( Scalar ‘ 𝑊 ) )  =  ( 0g ‘ ( Scalar ‘ 𝑊 ) ) | 
						
							| 10 | 1 6 7 8 2 3 9 | islbs | ⊢ ( 𝑊  ∈  dom  LBasis  →  ( 𝐵  ∈  𝐽  ↔  ( 𝐵  ⊆  𝑉  ∧  ( 𝑁 ‘ 𝐵 )  =  𝑉  ∧  ∀ 𝑥  ∈  𝐵 ∀ 𝑦  ∈  ( ( Base ‘ ( Scalar ‘ 𝑊 ) )  ∖  { ( 0g ‘ ( Scalar ‘ 𝑊 ) ) } ) ¬  ( 𝑦 (  ·𝑠  ‘ 𝑊 ) 𝑥 )  ∈  ( 𝑁 ‘ ( 𝐵  ∖  { 𝑥 } ) ) ) ) ) | 
						
							| 11 | 5 10 | syl | ⊢ ( 𝐵  ∈  𝐽  →  ( 𝐵  ∈  𝐽  ↔  ( 𝐵  ⊆  𝑉  ∧  ( 𝑁 ‘ 𝐵 )  =  𝑉  ∧  ∀ 𝑥  ∈  𝐵 ∀ 𝑦  ∈  ( ( Base ‘ ( Scalar ‘ 𝑊 ) )  ∖  { ( 0g ‘ ( Scalar ‘ 𝑊 ) ) } ) ¬  ( 𝑦 (  ·𝑠  ‘ 𝑊 ) 𝑥 )  ∈  ( 𝑁 ‘ ( 𝐵  ∖  { 𝑥 } ) ) ) ) ) | 
						
							| 12 | 11 | ibi | ⊢ ( 𝐵  ∈  𝐽  →  ( 𝐵  ⊆  𝑉  ∧  ( 𝑁 ‘ 𝐵 )  =  𝑉  ∧  ∀ 𝑥  ∈  𝐵 ∀ 𝑦  ∈  ( ( Base ‘ ( Scalar ‘ 𝑊 ) )  ∖  { ( 0g ‘ ( Scalar ‘ 𝑊 ) ) } ) ¬  ( 𝑦 (  ·𝑠  ‘ 𝑊 ) 𝑥 )  ∈  ( 𝑁 ‘ ( 𝐵  ∖  { 𝑥 } ) ) ) ) | 
						
							| 13 | 12 | simp2d | ⊢ ( 𝐵  ∈  𝐽  →  ( 𝑁 ‘ 𝐵 )  =  𝑉 ) |