| Step | Hyp | Ref | Expression | 
						
							| 1 |  | hhsst.1 | ⊢ 𝑈  =  〈 〈  +ℎ  ,   ·ℎ  〉 ,  normℎ 〉 | 
						
							| 2 |  | hhsst.2 | ⊢ 𝑊  =  〈 〈 (  +ℎ   ↾  ( 𝐻  ×  𝐻 ) ) ,  (  ·ℎ   ↾  ( ℂ  ×  𝐻 ) ) 〉 ,  ( normℎ  ↾  𝐻 ) 〉 | 
						
							| 3 |  | hhssp3.3 | ⊢ 𝑊  ∈  ( SubSp ‘ 𝑈 ) | 
						
							| 4 |  | hhssp3.4 | ⊢ 𝐻  ⊆   ℋ | 
						
							| 5 | 1 | hhnv | ⊢ 𝑈  ∈  NrmCVec | 
						
							| 6 | 1 | hh0v | ⊢ 0ℎ  =  ( 0vec ‘ 𝑈 ) | 
						
							| 7 |  | eqid | ⊢ ( 0vec ‘ 𝑊 )  =  ( 0vec ‘ 𝑊 ) | 
						
							| 8 |  | eqid | ⊢ ( SubSp ‘ 𝑈 )  =  ( SubSp ‘ 𝑈 ) | 
						
							| 9 | 6 7 8 | sspz | ⊢ ( ( 𝑈  ∈  NrmCVec  ∧  𝑊  ∈  ( SubSp ‘ 𝑈 ) )  →  ( 0vec ‘ 𝑊 )  =  0ℎ ) | 
						
							| 10 | 5 3 9 | mp2an | ⊢ ( 0vec ‘ 𝑊 )  =  0ℎ | 
						
							| 11 | 8 | sspnv | ⊢ ( ( 𝑈  ∈  NrmCVec  ∧  𝑊  ∈  ( SubSp ‘ 𝑈 ) )  →  𝑊  ∈  NrmCVec ) | 
						
							| 12 | 5 3 11 | mp2an | ⊢ 𝑊  ∈  NrmCVec | 
						
							| 13 |  | eqid | ⊢ ( BaseSet ‘ 𝑊 )  =  ( BaseSet ‘ 𝑊 ) | 
						
							| 14 | 13 7 | nvzcl | ⊢ ( 𝑊  ∈  NrmCVec  →  ( 0vec ‘ 𝑊 )  ∈  ( BaseSet ‘ 𝑊 ) ) | 
						
							| 15 | 12 14 | ax-mp | ⊢ ( 0vec ‘ 𝑊 )  ∈  ( BaseSet ‘ 𝑊 ) | 
						
							| 16 | 1 2 3 4 | hhshsslem1 | ⊢ 𝐻  =  ( BaseSet ‘ 𝑊 ) | 
						
							| 17 | 15 16 | eleqtrri | ⊢ ( 0vec ‘ 𝑊 )  ∈  𝐻 | 
						
							| 18 | 10 17 | eqeltrri | ⊢ 0ℎ  ∈  𝐻 | 
						
							| 19 | 4 18 | pm3.2i | ⊢ ( 𝐻  ⊆   ℋ  ∧  0ℎ  ∈  𝐻 ) | 
						
							| 20 | 1 | hhva | ⊢  +ℎ   =  (  +𝑣  ‘ 𝑈 ) | 
						
							| 21 |  | eqid | ⊢ (  +𝑣  ‘ 𝑊 )  =  (  +𝑣  ‘ 𝑊 ) | 
						
							| 22 | 16 20 21 8 | sspgval | ⊢ ( ( ( 𝑈  ∈  NrmCVec  ∧  𝑊  ∈  ( SubSp ‘ 𝑈 ) )  ∧  ( 𝑥  ∈  𝐻  ∧  𝑦  ∈  𝐻 ) )  →  ( 𝑥 (  +𝑣  ‘ 𝑊 ) 𝑦 )  =  ( 𝑥  +ℎ  𝑦 ) ) | 
						
							| 23 | 5 3 22 | mpanl12 | ⊢ ( ( 𝑥  ∈  𝐻  ∧  𝑦  ∈  𝐻 )  →  ( 𝑥 (  +𝑣  ‘ 𝑊 ) 𝑦 )  =  ( 𝑥  +ℎ  𝑦 ) ) | 
						
							| 24 | 16 21 | nvgcl | ⊢ ( ( 𝑊  ∈  NrmCVec  ∧  𝑥  ∈  𝐻  ∧  𝑦  ∈  𝐻 )  →  ( 𝑥 (  +𝑣  ‘ 𝑊 ) 𝑦 )  ∈  𝐻 ) | 
						
							| 25 | 12 24 | mp3an1 | ⊢ ( ( 𝑥  ∈  𝐻  ∧  𝑦  ∈  𝐻 )  →  ( 𝑥 (  +𝑣  ‘ 𝑊 ) 𝑦 )  ∈  𝐻 ) | 
						
							| 26 | 23 25 | eqeltrrd | ⊢ ( ( 𝑥  ∈  𝐻  ∧  𝑦  ∈  𝐻 )  →  ( 𝑥  +ℎ  𝑦 )  ∈  𝐻 ) | 
						
							| 27 | 26 | rgen2 | ⊢ ∀ 𝑥  ∈  𝐻 ∀ 𝑦  ∈  𝐻 ( 𝑥  +ℎ  𝑦 )  ∈  𝐻 | 
						
							| 28 | 1 | hhsm | ⊢  ·ℎ   =  (  ·𝑠OLD  ‘ 𝑈 ) | 
						
							| 29 |  | eqid | ⊢ (  ·𝑠OLD  ‘ 𝑊 )  =  (  ·𝑠OLD  ‘ 𝑊 ) | 
						
							| 30 | 16 28 29 8 | sspsval | ⊢ ( ( ( 𝑈  ∈  NrmCVec  ∧  𝑊  ∈  ( SubSp ‘ 𝑈 ) )  ∧  ( 𝑥  ∈  ℂ  ∧  𝑦  ∈  𝐻 ) )  →  ( 𝑥 (  ·𝑠OLD  ‘ 𝑊 ) 𝑦 )  =  ( 𝑥  ·ℎ  𝑦 ) ) | 
						
							| 31 | 5 3 30 | mpanl12 | ⊢ ( ( 𝑥  ∈  ℂ  ∧  𝑦  ∈  𝐻 )  →  ( 𝑥 (  ·𝑠OLD  ‘ 𝑊 ) 𝑦 )  =  ( 𝑥  ·ℎ  𝑦 ) ) | 
						
							| 32 | 16 29 | nvscl | ⊢ ( ( 𝑊  ∈  NrmCVec  ∧  𝑥  ∈  ℂ  ∧  𝑦  ∈  𝐻 )  →  ( 𝑥 (  ·𝑠OLD  ‘ 𝑊 ) 𝑦 )  ∈  𝐻 ) | 
						
							| 33 | 12 32 | mp3an1 | ⊢ ( ( 𝑥  ∈  ℂ  ∧  𝑦  ∈  𝐻 )  →  ( 𝑥 (  ·𝑠OLD  ‘ 𝑊 ) 𝑦 )  ∈  𝐻 ) | 
						
							| 34 | 31 33 | eqeltrrd | ⊢ ( ( 𝑥  ∈  ℂ  ∧  𝑦  ∈  𝐻 )  →  ( 𝑥  ·ℎ  𝑦 )  ∈  𝐻 ) | 
						
							| 35 | 34 | rgen2 | ⊢ ∀ 𝑥  ∈  ℂ ∀ 𝑦  ∈  𝐻 ( 𝑥  ·ℎ  𝑦 )  ∈  𝐻 | 
						
							| 36 | 27 35 | pm3.2i | ⊢ ( ∀ 𝑥  ∈  𝐻 ∀ 𝑦  ∈  𝐻 ( 𝑥  +ℎ  𝑦 )  ∈  𝐻  ∧  ∀ 𝑥  ∈  ℂ ∀ 𝑦  ∈  𝐻 ( 𝑥  ·ℎ  𝑦 )  ∈  𝐻 ) | 
						
							| 37 |  | issh2 | ⊢ ( 𝐻  ∈   Sℋ   ↔  ( ( 𝐻  ⊆   ℋ  ∧  0ℎ  ∈  𝐻 )  ∧  ( ∀ 𝑥  ∈  𝐻 ∀ 𝑦  ∈  𝐻 ( 𝑥  +ℎ  𝑦 )  ∈  𝐻  ∧  ∀ 𝑥  ∈  ℂ ∀ 𝑦  ∈  𝐻 ( 𝑥  ·ℎ  𝑦 )  ∈  𝐻 ) ) ) | 
						
							| 38 | 19 36 37 | mpbir2an | ⊢ 𝐻  ∈   Sℋ |