| Step | Hyp | Ref | Expression | 
						
							| 1 |  | dvhgrp.b | ⊢ 𝐵  =  ( Base ‘ 𝐾 ) | 
						
							| 2 |  | dvhgrp.h | ⊢ 𝐻  =  ( LHyp ‘ 𝐾 ) | 
						
							| 3 |  | dvhgrp.t | ⊢ 𝑇  =  ( ( LTrn ‘ 𝐾 ) ‘ 𝑊 ) | 
						
							| 4 |  | dvhgrp.e | ⊢ 𝐸  =  ( ( TEndo ‘ 𝐾 ) ‘ 𝑊 ) | 
						
							| 5 |  | dvhgrp.u | ⊢ 𝑈  =  ( ( DVecH ‘ 𝐾 ) ‘ 𝑊 ) | 
						
							| 6 |  | dvhgrp.d | ⊢ 𝐷  =  ( Scalar ‘ 𝑈 ) | 
						
							| 7 |  | dvhgrp.p | ⊢  ⨣   =  ( +g ‘ 𝐷 ) | 
						
							| 8 |  | dvhgrp.a | ⊢  +   =  ( +g ‘ 𝑈 ) | 
						
							| 9 |  | dvhgrp.o | ⊢  0   =  ( 0g ‘ 𝐷 ) | 
						
							| 10 |  | dvhgrp.i | ⊢ 𝐼  =  ( invg ‘ 𝐷 ) | 
						
							| 11 |  | eqid | ⊢ ( Base ‘ 𝑈 )  =  ( Base ‘ 𝑈 ) | 
						
							| 12 | 2 3 4 5 11 | dvhvbase | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  →  ( Base ‘ 𝑈 )  =  ( 𝑇  ×  𝐸 ) ) | 
						
							| 13 | 12 | eqcomd | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  →  ( 𝑇  ×  𝐸 )  =  ( Base ‘ 𝑈 ) ) | 
						
							| 14 | 8 | a1i | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  →   +   =  ( +g ‘ 𝑈 ) ) | 
						
							| 15 | 2 3 4 5 6 7 8 | dvhvaddcl | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  ( 𝑓  ∈  ( 𝑇  ×  𝐸 )  ∧  𝑔  ∈  ( 𝑇  ×  𝐸 ) ) )  →  ( 𝑓  +  𝑔 )  ∈  ( 𝑇  ×  𝐸 ) ) | 
						
							| 16 | 15 | 3impb | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑓  ∈  ( 𝑇  ×  𝐸 )  ∧  𝑔  ∈  ( 𝑇  ×  𝐸 ) )  →  ( 𝑓  +  𝑔 )  ∈  ( 𝑇  ×  𝐸 ) ) | 
						
							| 17 | 2 3 4 5 6 7 8 | dvhvaddass | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  ( 𝑓  ∈  ( 𝑇  ×  𝐸 )  ∧  𝑔  ∈  ( 𝑇  ×  𝐸 )  ∧  ℎ  ∈  ( 𝑇  ×  𝐸 ) ) )  →  ( ( 𝑓  +  𝑔 )  +  ℎ )  =  ( 𝑓  +  ( 𝑔  +  ℎ ) ) ) | 
						
							| 18 | 1 2 3 | idltrn | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  →  (  I   ↾  𝐵 )  ∈  𝑇 ) | 
						
							| 19 |  | eqid | ⊢ ( ( EDRing ‘ 𝐾 ) ‘ 𝑊 )  =  ( ( EDRing ‘ 𝐾 ) ‘ 𝑊 ) | 
						
							| 20 | 2 19 5 6 | dvhsca | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  →  𝐷  =  ( ( EDRing ‘ 𝐾 ) ‘ 𝑊 ) ) | 
						
							| 21 | 2 19 | erngdv | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  →  ( ( EDRing ‘ 𝐾 ) ‘ 𝑊 )  ∈  DivRing ) | 
						
							| 22 | 20 21 | eqeltrd | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  →  𝐷  ∈  DivRing ) | 
						
							| 23 |  | drnggrp | ⊢ ( 𝐷  ∈  DivRing  →  𝐷  ∈  Grp ) | 
						
							| 24 | 22 23 | syl | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  →  𝐷  ∈  Grp ) | 
						
							| 25 |  | eqid | ⊢ ( Base ‘ 𝐷 )  =  ( Base ‘ 𝐷 ) | 
						
							| 26 | 25 9 | grpidcl | ⊢ ( 𝐷  ∈  Grp  →   0   ∈  ( Base ‘ 𝐷 ) ) | 
						
							| 27 | 24 26 | syl | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  →   0   ∈  ( Base ‘ 𝐷 ) ) | 
						
							| 28 | 2 4 5 6 25 | dvhbase | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  →  ( Base ‘ 𝐷 )  =  𝐸 ) | 
						
							| 29 | 27 28 | eleqtrd | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  →   0   ∈  𝐸 ) | 
						
							| 30 |  | opelxpi | ⊢ ( ( (  I   ↾  𝐵 )  ∈  𝑇  ∧   0   ∈  𝐸 )  →  〈 (  I   ↾  𝐵 ) ,   0  〉  ∈  ( 𝑇  ×  𝐸 ) ) | 
						
							| 31 | 18 29 30 | syl2anc | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  →  〈 (  I   ↾  𝐵 ) ,   0  〉  ∈  ( 𝑇  ×  𝐸 ) ) | 
						
							| 32 |  | simpl | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑓  ∈  ( 𝑇  ×  𝐸 ) )  →  ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 ) ) | 
						
							| 33 | 18 | adantr | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑓  ∈  ( 𝑇  ×  𝐸 ) )  →  (  I   ↾  𝐵 )  ∈  𝑇 ) | 
						
							| 34 | 29 | adantr | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑓  ∈  ( 𝑇  ×  𝐸 ) )  →   0   ∈  𝐸 ) | 
						
							| 35 |  | xp1st | ⊢ ( 𝑓  ∈  ( 𝑇  ×  𝐸 )  →  ( 1st  ‘ 𝑓 )  ∈  𝑇 ) | 
						
							| 36 | 35 | adantl | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑓  ∈  ( 𝑇  ×  𝐸 ) )  →  ( 1st  ‘ 𝑓 )  ∈  𝑇 ) | 
						
							| 37 |  | xp2nd | ⊢ ( 𝑓  ∈  ( 𝑇  ×  𝐸 )  →  ( 2nd  ‘ 𝑓 )  ∈  𝐸 ) | 
						
							| 38 | 37 | adantl | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑓  ∈  ( 𝑇  ×  𝐸 ) )  →  ( 2nd  ‘ 𝑓 )  ∈  𝐸 ) | 
						
							| 39 | 2 3 4 5 6 8 7 | dvhopvadd | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  ( (  I   ↾  𝐵 )  ∈  𝑇  ∧   0   ∈  𝐸 )  ∧  ( ( 1st  ‘ 𝑓 )  ∈  𝑇  ∧  ( 2nd  ‘ 𝑓 )  ∈  𝐸 ) )  →  ( 〈 (  I   ↾  𝐵 ) ,   0  〉  +  〈 ( 1st  ‘ 𝑓 ) ,  ( 2nd  ‘ 𝑓 ) 〉 )  =  〈 ( (  I   ↾  𝐵 )  ∘  ( 1st  ‘ 𝑓 ) ) ,  (  0   ⨣  ( 2nd  ‘ 𝑓 ) ) 〉 ) | 
						
							| 40 | 32 33 34 36 38 39 | syl122anc | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑓  ∈  ( 𝑇  ×  𝐸 ) )  →  ( 〈 (  I   ↾  𝐵 ) ,   0  〉  +  〈 ( 1st  ‘ 𝑓 ) ,  ( 2nd  ‘ 𝑓 ) 〉 )  =  〈 ( (  I   ↾  𝐵 )  ∘  ( 1st  ‘ 𝑓 ) ) ,  (  0   ⨣  ( 2nd  ‘ 𝑓 ) ) 〉 ) | 
						
							| 41 | 1 2 3 | ltrn1o | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  ( 1st  ‘ 𝑓 )  ∈  𝑇 )  →  ( 1st  ‘ 𝑓 ) : 𝐵 –1-1-onto→ 𝐵 ) | 
						
							| 42 | 36 41 | syldan | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑓  ∈  ( 𝑇  ×  𝐸 ) )  →  ( 1st  ‘ 𝑓 ) : 𝐵 –1-1-onto→ 𝐵 ) | 
						
							| 43 |  | f1of | ⊢ ( ( 1st  ‘ 𝑓 ) : 𝐵 –1-1-onto→ 𝐵  →  ( 1st  ‘ 𝑓 ) : 𝐵 ⟶ 𝐵 ) | 
						
							| 44 |  | fcoi2 | ⊢ ( ( 1st  ‘ 𝑓 ) : 𝐵 ⟶ 𝐵  →  ( (  I   ↾  𝐵 )  ∘  ( 1st  ‘ 𝑓 ) )  =  ( 1st  ‘ 𝑓 ) ) | 
						
							| 45 | 42 43 44 | 3syl | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑓  ∈  ( 𝑇  ×  𝐸 ) )  →  ( (  I   ↾  𝐵 )  ∘  ( 1st  ‘ 𝑓 ) )  =  ( 1st  ‘ 𝑓 ) ) | 
						
							| 46 | 24 | adantr | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑓  ∈  ( 𝑇  ×  𝐸 ) )  →  𝐷  ∈  Grp ) | 
						
							| 47 | 28 | adantr | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑓  ∈  ( 𝑇  ×  𝐸 ) )  →  ( Base ‘ 𝐷 )  =  𝐸 ) | 
						
							| 48 | 38 47 | eleqtrrd | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑓  ∈  ( 𝑇  ×  𝐸 ) )  →  ( 2nd  ‘ 𝑓 )  ∈  ( Base ‘ 𝐷 ) ) | 
						
							| 49 | 25 7 9 | grplid | ⊢ ( ( 𝐷  ∈  Grp  ∧  ( 2nd  ‘ 𝑓 )  ∈  ( Base ‘ 𝐷 ) )  →  (  0   ⨣  ( 2nd  ‘ 𝑓 ) )  =  ( 2nd  ‘ 𝑓 ) ) | 
						
							| 50 | 46 48 49 | syl2anc | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑓  ∈  ( 𝑇  ×  𝐸 ) )  →  (  0   ⨣  ( 2nd  ‘ 𝑓 ) )  =  ( 2nd  ‘ 𝑓 ) ) | 
						
							| 51 | 45 50 | opeq12d | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑓  ∈  ( 𝑇  ×  𝐸 ) )  →  〈 ( (  I   ↾  𝐵 )  ∘  ( 1st  ‘ 𝑓 ) ) ,  (  0   ⨣  ( 2nd  ‘ 𝑓 ) ) 〉  =  〈 ( 1st  ‘ 𝑓 ) ,  ( 2nd  ‘ 𝑓 ) 〉 ) | 
						
							| 52 | 40 51 | eqtrd | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑓  ∈  ( 𝑇  ×  𝐸 ) )  →  ( 〈 (  I   ↾  𝐵 ) ,   0  〉  +  〈 ( 1st  ‘ 𝑓 ) ,  ( 2nd  ‘ 𝑓 ) 〉 )  =  〈 ( 1st  ‘ 𝑓 ) ,  ( 2nd  ‘ 𝑓 ) 〉 ) | 
						
							| 53 |  | 1st2nd2 | ⊢ ( 𝑓  ∈  ( 𝑇  ×  𝐸 )  →  𝑓  =  〈 ( 1st  ‘ 𝑓 ) ,  ( 2nd  ‘ 𝑓 ) 〉 ) | 
						
							| 54 | 53 | adantl | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑓  ∈  ( 𝑇  ×  𝐸 ) )  →  𝑓  =  〈 ( 1st  ‘ 𝑓 ) ,  ( 2nd  ‘ 𝑓 ) 〉 ) | 
						
							| 55 | 54 | oveq2d | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑓  ∈  ( 𝑇  ×  𝐸 ) )  →  ( 〈 (  I   ↾  𝐵 ) ,   0  〉  +  𝑓 )  =  ( 〈 (  I   ↾  𝐵 ) ,   0  〉  +  〈 ( 1st  ‘ 𝑓 ) ,  ( 2nd  ‘ 𝑓 ) 〉 ) ) | 
						
							| 56 | 52 55 54 | 3eqtr4d | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑓  ∈  ( 𝑇  ×  𝐸 ) )  →  ( 〈 (  I   ↾  𝐵 ) ,   0  〉  +  𝑓 )  =  𝑓 ) | 
						
							| 57 | 2 3 | ltrncnv | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  ( 1st  ‘ 𝑓 )  ∈  𝑇 )  →  ◡ ( 1st  ‘ 𝑓 )  ∈  𝑇 ) | 
						
							| 58 | 36 57 | syldan | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑓  ∈  ( 𝑇  ×  𝐸 ) )  →  ◡ ( 1st  ‘ 𝑓 )  ∈  𝑇 ) | 
						
							| 59 | 25 10 | grpinvcl | ⊢ ( ( 𝐷  ∈  Grp  ∧  ( 2nd  ‘ 𝑓 )  ∈  ( Base ‘ 𝐷 ) )  →  ( 𝐼 ‘ ( 2nd  ‘ 𝑓 ) )  ∈  ( Base ‘ 𝐷 ) ) | 
						
							| 60 | 46 48 59 | syl2anc | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑓  ∈  ( 𝑇  ×  𝐸 ) )  →  ( 𝐼 ‘ ( 2nd  ‘ 𝑓 ) )  ∈  ( Base ‘ 𝐷 ) ) | 
						
							| 61 | 60 47 | eleqtrd | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑓  ∈  ( 𝑇  ×  𝐸 ) )  →  ( 𝐼 ‘ ( 2nd  ‘ 𝑓 ) )  ∈  𝐸 ) | 
						
							| 62 |  | opelxpi | ⊢ ( ( ◡ ( 1st  ‘ 𝑓 )  ∈  𝑇  ∧  ( 𝐼 ‘ ( 2nd  ‘ 𝑓 ) )  ∈  𝐸 )  →  〈 ◡ ( 1st  ‘ 𝑓 ) ,  ( 𝐼 ‘ ( 2nd  ‘ 𝑓 ) ) 〉  ∈  ( 𝑇  ×  𝐸 ) ) | 
						
							| 63 | 58 61 62 | syl2anc | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑓  ∈  ( 𝑇  ×  𝐸 ) )  →  〈 ◡ ( 1st  ‘ 𝑓 ) ,  ( 𝐼 ‘ ( 2nd  ‘ 𝑓 ) ) 〉  ∈  ( 𝑇  ×  𝐸 ) ) | 
						
							| 64 | 54 | oveq2d | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑓  ∈  ( 𝑇  ×  𝐸 ) )  →  ( 〈 ◡ ( 1st  ‘ 𝑓 ) ,  ( 𝐼 ‘ ( 2nd  ‘ 𝑓 ) ) 〉  +  𝑓 )  =  ( 〈 ◡ ( 1st  ‘ 𝑓 ) ,  ( 𝐼 ‘ ( 2nd  ‘ 𝑓 ) ) 〉  +  〈 ( 1st  ‘ 𝑓 ) ,  ( 2nd  ‘ 𝑓 ) 〉 ) ) | 
						
							| 65 | 2 3 4 5 6 8 7 | dvhopvadd | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  ( ◡ ( 1st  ‘ 𝑓 )  ∈  𝑇  ∧  ( 𝐼 ‘ ( 2nd  ‘ 𝑓 ) )  ∈  𝐸 )  ∧  ( ( 1st  ‘ 𝑓 )  ∈  𝑇  ∧  ( 2nd  ‘ 𝑓 )  ∈  𝐸 ) )  →  ( 〈 ◡ ( 1st  ‘ 𝑓 ) ,  ( 𝐼 ‘ ( 2nd  ‘ 𝑓 ) ) 〉  +  〈 ( 1st  ‘ 𝑓 ) ,  ( 2nd  ‘ 𝑓 ) 〉 )  =  〈 ( ◡ ( 1st  ‘ 𝑓 )  ∘  ( 1st  ‘ 𝑓 ) ) ,  ( ( 𝐼 ‘ ( 2nd  ‘ 𝑓 ) )  ⨣  ( 2nd  ‘ 𝑓 ) ) 〉 ) | 
						
							| 66 | 32 58 61 36 38 65 | syl122anc | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑓  ∈  ( 𝑇  ×  𝐸 ) )  →  ( 〈 ◡ ( 1st  ‘ 𝑓 ) ,  ( 𝐼 ‘ ( 2nd  ‘ 𝑓 ) ) 〉  +  〈 ( 1st  ‘ 𝑓 ) ,  ( 2nd  ‘ 𝑓 ) 〉 )  =  〈 ( ◡ ( 1st  ‘ 𝑓 )  ∘  ( 1st  ‘ 𝑓 ) ) ,  ( ( 𝐼 ‘ ( 2nd  ‘ 𝑓 ) )  ⨣  ( 2nd  ‘ 𝑓 ) ) 〉 ) | 
						
							| 67 |  | f1ococnv1 | ⊢ ( ( 1st  ‘ 𝑓 ) : 𝐵 –1-1-onto→ 𝐵  →  ( ◡ ( 1st  ‘ 𝑓 )  ∘  ( 1st  ‘ 𝑓 ) )  =  (  I   ↾  𝐵 ) ) | 
						
							| 68 | 42 67 | syl | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑓  ∈  ( 𝑇  ×  𝐸 ) )  →  ( ◡ ( 1st  ‘ 𝑓 )  ∘  ( 1st  ‘ 𝑓 ) )  =  (  I   ↾  𝐵 ) ) | 
						
							| 69 | 25 7 9 10 | grplinv | ⊢ ( ( 𝐷  ∈  Grp  ∧  ( 2nd  ‘ 𝑓 )  ∈  ( Base ‘ 𝐷 ) )  →  ( ( 𝐼 ‘ ( 2nd  ‘ 𝑓 ) )  ⨣  ( 2nd  ‘ 𝑓 ) )  =   0  ) | 
						
							| 70 | 46 48 69 | syl2anc | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑓  ∈  ( 𝑇  ×  𝐸 ) )  →  ( ( 𝐼 ‘ ( 2nd  ‘ 𝑓 ) )  ⨣  ( 2nd  ‘ 𝑓 ) )  =   0  ) | 
						
							| 71 | 68 70 | opeq12d | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑓  ∈  ( 𝑇  ×  𝐸 ) )  →  〈 ( ◡ ( 1st  ‘ 𝑓 )  ∘  ( 1st  ‘ 𝑓 ) ) ,  ( ( 𝐼 ‘ ( 2nd  ‘ 𝑓 ) )  ⨣  ( 2nd  ‘ 𝑓 ) ) 〉  =  〈 (  I   ↾  𝐵 ) ,   0  〉 ) | 
						
							| 72 | 66 71 | eqtrd | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑓  ∈  ( 𝑇  ×  𝐸 ) )  →  ( 〈 ◡ ( 1st  ‘ 𝑓 ) ,  ( 𝐼 ‘ ( 2nd  ‘ 𝑓 ) ) 〉  +  〈 ( 1st  ‘ 𝑓 ) ,  ( 2nd  ‘ 𝑓 ) 〉 )  =  〈 (  I   ↾  𝐵 ) ,   0  〉 ) | 
						
							| 73 | 64 72 | eqtrd | ⊢ ( ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  ∧  𝑓  ∈  ( 𝑇  ×  𝐸 ) )  →  ( 〈 ◡ ( 1st  ‘ 𝑓 ) ,  ( 𝐼 ‘ ( 2nd  ‘ 𝑓 ) ) 〉  +  𝑓 )  =  〈 (  I   ↾  𝐵 ) ,   0  〉 ) | 
						
							| 74 | 13 14 16 17 31 56 63 73 | isgrpd | ⊢ ( ( 𝐾  ∈  HL  ∧  𝑊  ∈  𝐻 )  →  𝑈  ∈  Grp ) |