| Step | Hyp | Ref | Expression | 
						
							| 1 |  | 0prjspnlem.b | ⊢ 𝐵  =  ( ( Base ‘ 𝑊 )  ∖  { ( 0g ‘ 𝑊 ) } ) | 
						
							| 2 |  | 0prjspnlem.w | ⊢ 𝑊  =  ( 𝐾  freeLMod  ( 0 ... 0 ) ) | 
						
							| 3 |  | 0prjspnlem.1 | ⊢  1   =  ( ( 𝐾  unitVec  ( 0 ... 0 ) ) ‘ 0 ) | 
						
							| 4 |  | drngnzr | ⊢ ( 𝐾  ∈  DivRing  →  𝐾  ∈  NzRing ) | 
						
							| 5 |  | ovex | ⊢ ( 0 ... 0 )  ∈  V | 
						
							| 6 |  | c0ex | ⊢ 0  ∈  V | 
						
							| 7 | 6 | snid | ⊢ 0  ∈  { 0 } | 
						
							| 8 |  | fz0sn | ⊢ ( 0 ... 0 )  =  { 0 } | 
						
							| 9 | 7 8 | eleqtrri | ⊢ 0  ∈  ( 0 ... 0 ) | 
						
							| 10 |  | nzrring | ⊢ ( 𝐾  ∈  NzRing  →  𝐾  ∈  Ring ) | 
						
							| 11 |  | eqid | ⊢ ( 𝐾  unitVec  ( 0 ... 0 ) )  =  ( 𝐾  unitVec  ( 0 ... 0 ) ) | 
						
							| 12 |  | eqid | ⊢ ( Base ‘ 𝑊 )  =  ( Base ‘ 𝑊 ) | 
						
							| 13 | 11 2 12 | uvccl | ⊢ ( ( 𝐾  ∈  Ring  ∧  ( 0 ... 0 )  ∈  V  ∧  0  ∈  ( 0 ... 0 ) )  →  ( ( 𝐾  unitVec  ( 0 ... 0 ) ) ‘ 0 )  ∈  ( Base ‘ 𝑊 ) ) | 
						
							| 14 | 10 13 | syl3an1 | ⊢ ( ( 𝐾  ∈  NzRing  ∧  ( 0 ... 0 )  ∈  V  ∧  0  ∈  ( 0 ... 0 ) )  →  ( ( 𝐾  unitVec  ( 0 ... 0 ) ) ‘ 0 )  ∈  ( Base ‘ 𝑊 ) ) | 
						
							| 15 |  | eqid | ⊢ ( 0g ‘ 𝑊 )  =  ( 0g ‘ 𝑊 ) | 
						
							| 16 | 11 2 12 15 | uvcn0 | ⊢ ( ( 𝐾  ∈  NzRing  ∧  ( 0 ... 0 )  ∈  V  ∧  0  ∈  ( 0 ... 0 ) )  →  ( ( 𝐾  unitVec  ( 0 ... 0 ) ) ‘ 0 )  ≠  ( 0g ‘ 𝑊 ) ) | 
						
							| 17 |  | eldifsn | ⊢ ( ( ( 𝐾  unitVec  ( 0 ... 0 ) ) ‘ 0 )  ∈  ( ( Base ‘ 𝑊 )  ∖  { ( 0g ‘ 𝑊 ) } )  ↔  ( ( ( 𝐾  unitVec  ( 0 ... 0 ) ) ‘ 0 )  ∈  ( Base ‘ 𝑊 )  ∧  ( ( 𝐾  unitVec  ( 0 ... 0 ) ) ‘ 0 )  ≠  ( 0g ‘ 𝑊 ) ) ) | 
						
							| 18 | 14 16 17 | sylanbrc | ⊢ ( ( 𝐾  ∈  NzRing  ∧  ( 0 ... 0 )  ∈  V  ∧  0  ∈  ( 0 ... 0 ) )  →  ( ( 𝐾  unitVec  ( 0 ... 0 ) ) ‘ 0 )  ∈  ( ( Base ‘ 𝑊 )  ∖  { ( 0g ‘ 𝑊 ) } ) ) | 
						
							| 19 | 5 9 18 | mp3an23 | ⊢ ( 𝐾  ∈  NzRing  →  ( ( 𝐾  unitVec  ( 0 ... 0 ) ) ‘ 0 )  ∈  ( ( Base ‘ 𝑊 )  ∖  { ( 0g ‘ 𝑊 ) } ) ) | 
						
							| 20 | 4 19 | syl | ⊢ ( 𝐾  ∈  DivRing  →  ( ( 𝐾  unitVec  ( 0 ... 0 ) ) ‘ 0 )  ∈  ( ( Base ‘ 𝑊 )  ∖  { ( 0g ‘ 𝑊 ) } ) ) | 
						
							| 21 | 20 3 1 | 3eltr4g | ⊢ ( 𝐾  ∈  DivRing  →   1   ∈  𝐵 ) |