| Step | Hyp | Ref | Expression | 
						
							| 1 |  | phlsrng.f | ⊢ 𝐹  =  ( Scalar ‘ 𝑊 ) | 
						
							| 2 |  | phllmhm.h | ⊢  ,   =  ( ·𝑖 ‘ 𝑊 ) | 
						
							| 3 |  | phllmhm.v | ⊢ 𝑉  =  ( Base ‘ 𝑊 ) | 
						
							| 4 |  | ipsubdir.m | ⊢  −   =  ( -g ‘ 𝑊 ) | 
						
							| 5 |  | ipsubdir.s | ⊢ 𝑆  =  ( -g ‘ 𝐹 ) | 
						
							| 6 |  | simpl | ⊢ ( ( 𝑊  ∈  PreHil  ∧  ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉  ∧  𝐶  ∈  𝑉 ) )  →  𝑊  ∈  PreHil ) | 
						
							| 7 |  | phllmod | ⊢ ( 𝑊  ∈  PreHil  →  𝑊  ∈  LMod ) | 
						
							| 8 | 7 | adantr | ⊢ ( ( 𝑊  ∈  PreHil  ∧  ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉  ∧  𝐶  ∈  𝑉 ) )  →  𝑊  ∈  LMod ) | 
						
							| 9 |  | lmodgrp | ⊢ ( 𝑊  ∈  LMod  →  𝑊  ∈  Grp ) | 
						
							| 10 | 8 9 | syl | ⊢ ( ( 𝑊  ∈  PreHil  ∧  ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉  ∧  𝐶  ∈  𝑉 ) )  →  𝑊  ∈  Grp ) | 
						
							| 11 |  | simpr1 | ⊢ ( ( 𝑊  ∈  PreHil  ∧  ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉  ∧  𝐶  ∈  𝑉 ) )  →  𝐴  ∈  𝑉 ) | 
						
							| 12 |  | simpr2 | ⊢ ( ( 𝑊  ∈  PreHil  ∧  ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉  ∧  𝐶  ∈  𝑉 ) )  →  𝐵  ∈  𝑉 ) | 
						
							| 13 | 3 4 | grpsubcl | ⊢ ( ( 𝑊  ∈  Grp  ∧  𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉 )  →  ( 𝐴  −  𝐵 )  ∈  𝑉 ) | 
						
							| 14 | 10 11 12 13 | syl3anc | ⊢ ( ( 𝑊  ∈  PreHil  ∧  ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉  ∧  𝐶  ∈  𝑉 ) )  →  ( 𝐴  −  𝐵 )  ∈  𝑉 ) | 
						
							| 15 |  | simpr3 | ⊢ ( ( 𝑊  ∈  PreHil  ∧  ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉  ∧  𝐶  ∈  𝑉 ) )  →  𝐶  ∈  𝑉 ) | 
						
							| 16 |  | eqid | ⊢ ( +g ‘ 𝑊 )  =  ( +g ‘ 𝑊 ) | 
						
							| 17 |  | eqid | ⊢ ( +g ‘ 𝐹 )  =  ( +g ‘ 𝐹 ) | 
						
							| 18 | 1 2 3 16 17 | ipdir | ⊢ ( ( 𝑊  ∈  PreHil  ∧  ( ( 𝐴  −  𝐵 )  ∈  𝑉  ∧  𝐵  ∈  𝑉  ∧  𝐶  ∈  𝑉 ) )  →  ( ( ( 𝐴  −  𝐵 ) ( +g ‘ 𝑊 ) 𝐵 )  ,  𝐶 )  =  ( ( ( 𝐴  −  𝐵 )  ,  𝐶 ) ( +g ‘ 𝐹 ) ( 𝐵  ,  𝐶 ) ) ) | 
						
							| 19 | 6 14 12 15 18 | syl13anc | ⊢ ( ( 𝑊  ∈  PreHil  ∧  ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉  ∧  𝐶  ∈  𝑉 ) )  →  ( ( ( 𝐴  −  𝐵 ) ( +g ‘ 𝑊 ) 𝐵 )  ,  𝐶 )  =  ( ( ( 𝐴  −  𝐵 )  ,  𝐶 ) ( +g ‘ 𝐹 ) ( 𝐵  ,  𝐶 ) ) ) | 
						
							| 20 | 3 16 4 | grpnpcan | ⊢ ( ( 𝑊  ∈  Grp  ∧  𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉 )  →  ( ( 𝐴  −  𝐵 ) ( +g ‘ 𝑊 ) 𝐵 )  =  𝐴 ) | 
						
							| 21 | 10 11 12 20 | syl3anc | ⊢ ( ( 𝑊  ∈  PreHil  ∧  ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉  ∧  𝐶  ∈  𝑉 ) )  →  ( ( 𝐴  −  𝐵 ) ( +g ‘ 𝑊 ) 𝐵 )  =  𝐴 ) | 
						
							| 22 | 21 | oveq1d | ⊢ ( ( 𝑊  ∈  PreHil  ∧  ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉  ∧  𝐶  ∈  𝑉 ) )  →  ( ( ( 𝐴  −  𝐵 ) ( +g ‘ 𝑊 ) 𝐵 )  ,  𝐶 )  =  ( 𝐴  ,  𝐶 ) ) | 
						
							| 23 | 19 22 | eqtr3d | ⊢ ( ( 𝑊  ∈  PreHil  ∧  ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉  ∧  𝐶  ∈  𝑉 ) )  →  ( ( ( 𝐴  −  𝐵 )  ,  𝐶 ) ( +g ‘ 𝐹 ) ( 𝐵  ,  𝐶 ) )  =  ( 𝐴  ,  𝐶 ) ) | 
						
							| 24 | 1 | lmodfgrp | ⊢ ( 𝑊  ∈  LMod  →  𝐹  ∈  Grp ) | 
						
							| 25 | 8 24 | syl | ⊢ ( ( 𝑊  ∈  PreHil  ∧  ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉  ∧  𝐶  ∈  𝑉 ) )  →  𝐹  ∈  Grp ) | 
						
							| 26 |  | eqid | ⊢ ( Base ‘ 𝐹 )  =  ( Base ‘ 𝐹 ) | 
						
							| 27 | 1 2 3 26 | ipcl | ⊢ ( ( 𝑊  ∈  PreHil  ∧  𝐴  ∈  𝑉  ∧  𝐶  ∈  𝑉 )  →  ( 𝐴  ,  𝐶 )  ∈  ( Base ‘ 𝐹 ) ) | 
						
							| 28 | 6 11 15 27 | syl3anc | ⊢ ( ( 𝑊  ∈  PreHil  ∧  ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉  ∧  𝐶  ∈  𝑉 ) )  →  ( 𝐴  ,  𝐶 )  ∈  ( Base ‘ 𝐹 ) ) | 
						
							| 29 | 1 2 3 26 | ipcl | ⊢ ( ( 𝑊  ∈  PreHil  ∧  𝐵  ∈  𝑉  ∧  𝐶  ∈  𝑉 )  →  ( 𝐵  ,  𝐶 )  ∈  ( Base ‘ 𝐹 ) ) | 
						
							| 30 | 6 12 15 29 | syl3anc | ⊢ ( ( 𝑊  ∈  PreHil  ∧  ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉  ∧  𝐶  ∈  𝑉 ) )  →  ( 𝐵  ,  𝐶 )  ∈  ( Base ‘ 𝐹 ) ) | 
						
							| 31 | 1 2 3 26 | ipcl | ⊢ ( ( 𝑊  ∈  PreHil  ∧  ( 𝐴  −  𝐵 )  ∈  𝑉  ∧  𝐶  ∈  𝑉 )  →  ( ( 𝐴  −  𝐵 )  ,  𝐶 )  ∈  ( Base ‘ 𝐹 ) ) | 
						
							| 32 | 6 14 15 31 | syl3anc | ⊢ ( ( 𝑊  ∈  PreHil  ∧  ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉  ∧  𝐶  ∈  𝑉 ) )  →  ( ( 𝐴  −  𝐵 )  ,  𝐶 )  ∈  ( Base ‘ 𝐹 ) ) | 
						
							| 33 | 26 17 5 | grpsubadd | ⊢ ( ( 𝐹  ∈  Grp  ∧  ( ( 𝐴  ,  𝐶 )  ∈  ( Base ‘ 𝐹 )  ∧  ( 𝐵  ,  𝐶 )  ∈  ( Base ‘ 𝐹 )  ∧  ( ( 𝐴  −  𝐵 )  ,  𝐶 )  ∈  ( Base ‘ 𝐹 ) ) )  →  ( ( ( 𝐴  ,  𝐶 ) 𝑆 ( 𝐵  ,  𝐶 ) )  =  ( ( 𝐴  −  𝐵 )  ,  𝐶 )  ↔  ( ( ( 𝐴  −  𝐵 )  ,  𝐶 ) ( +g ‘ 𝐹 ) ( 𝐵  ,  𝐶 ) )  =  ( 𝐴  ,  𝐶 ) ) ) | 
						
							| 34 | 25 28 30 32 33 | syl13anc | ⊢ ( ( 𝑊  ∈  PreHil  ∧  ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉  ∧  𝐶  ∈  𝑉 ) )  →  ( ( ( 𝐴  ,  𝐶 ) 𝑆 ( 𝐵  ,  𝐶 ) )  =  ( ( 𝐴  −  𝐵 )  ,  𝐶 )  ↔  ( ( ( 𝐴  −  𝐵 )  ,  𝐶 ) ( +g ‘ 𝐹 ) ( 𝐵  ,  𝐶 ) )  =  ( 𝐴  ,  𝐶 ) ) ) | 
						
							| 35 | 23 34 | mpbird | ⊢ ( ( 𝑊  ∈  PreHil  ∧  ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉  ∧  𝐶  ∈  𝑉 ) )  →  ( ( 𝐴  ,  𝐶 ) 𝑆 ( 𝐵  ,  𝐶 ) )  =  ( ( 𝐴  −  𝐵 )  ,  𝐶 ) ) | 
						
							| 36 | 35 | eqcomd | ⊢ ( ( 𝑊  ∈  PreHil  ∧  ( 𝐴  ∈  𝑉  ∧  𝐵  ∈  𝑉  ∧  𝐶  ∈  𝑉 ) )  →  ( ( 𝐴  −  𝐵 )  ,  𝐶 )  =  ( ( 𝐴  ,  𝐶 ) 𝑆 ( 𝐵  ,  𝐶 ) ) ) |