| Step | Hyp | Ref | Expression | 
						
							| 1 |  | hvass.1 | ⊢ 𝐴  ∈   ℋ | 
						
							| 2 |  | hvass.2 | ⊢ 𝐵  ∈   ℋ | 
						
							| 3 |  | hvass.3 | ⊢ 𝐶  ∈   ℋ | 
						
							| 4 |  | hvadd4.4 | ⊢ 𝐷  ∈   ℋ | 
						
							| 5 |  | neg1cn | ⊢ - 1  ∈  ℂ | 
						
							| 6 | 5 2 | hvmulcli | ⊢ ( - 1  ·ℎ  𝐵 )  ∈   ℋ | 
						
							| 7 | 5 3 | hvmulcli | ⊢ ( - 1  ·ℎ  𝐶 )  ∈   ℋ | 
						
							| 8 | 5 4 | hvmulcli | ⊢ ( - 1  ·ℎ  𝐷 )  ∈   ℋ | 
						
							| 9 | 5 8 | hvmulcli | ⊢ ( - 1  ·ℎ  ( - 1  ·ℎ  𝐷 ) )  ∈   ℋ | 
						
							| 10 | 1 6 7 9 | hvadd4i | ⊢ ( ( 𝐴  +ℎ  ( - 1  ·ℎ  𝐵 ) )  +ℎ  ( ( - 1  ·ℎ  𝐶 )  +ℎ  ( - 1  ·ℎ  ( - 1  ·ℎ  𝐷 ) ) ) )  =  ( ( 𝐴  +ℎ  ( - 1  ·ℎ  𝐶 ) )  +ℎ  ( ( - 1  ·ℎ  𝐵 )  +ℎ  ( - 1  ·ℎ  ( - 1  ·ℎ  𝐷 ) ) ) ) | 
						
							| 11 | 5 3 8 | hvdistr1i | ⊢ ( - 1  ·ℎ  ( 𝐶  +ℎ  ( - 1  ·ℎ  𝐷 ) ) )  =  ( ( - 1  ·ℎ  𝐶 )  +ℎ  ( - 1  ·ℎ  ( - 1  ·ℎ  𝐷 ) ) ) | 
						
							| 12 | 11 | oveq2i | ⊢ ( ( 𝐴  +ℎ  ( - 1  ·ℎ  𝐵 ) )  +ℎ  ( - 1  ·ℎ  ( 𝐶  +ℎ  ( - 1  ·ℎ  𝐷 ) ) ) )  =  ( ( 𝐴  +ℎ  ( - 1  ·ℎ  𝐵 ) )  +ℎ  ( ( - 1  ·ℎ  𝐶 )  +ℎ  ( - 1  ·ℎ  ( - 1  ·ℎ  𝐷 ) ) ) ) | 
						
							| 13 | 5 2 8 | hvdistr1i | ⊢ ( - 1  ·ℎ  ( 𝐵  +ℎ  ( - 1  ·ℎ  𝐷 ) ) )  =  ( ( - 1  ·ℎ  𝐵 )  +ℎ  ( - 1  ·ℎ  ( - 1  ·ℎ  𝐷 ) ) ) | 
						
							| 14 | 13 | oveq2i | ⊢ ( ( 𝐴  +ℎ  ( - 1  ·ℎ  𝐶 ) )  +ℎ  ( - 1  ·ℎ  ( 𝐵  +ℎ  ( - 1  ·ℎ  𝐷 ) ) ) )  =  ( ( 𝐴  +ℎ  ( - 1  ·ℎ  𝐶 ) )  +ℎ  ( ( - 1  ·ℎ  𝐵 )  +ℎ  ( - 1  ·ℎ  ( - 1  ·ℎ  𝐷 ) ) ) ) | 
						
							| 15 | 10 12 14 | 3eqtr4i | ⊢ ( ( 𝐴  +ℎ  ( - 1  ·ℎ  𝐵 ) )  +ℎ  ( - 1  ·ℎ  ( 𝐶  +ℎ  ( - 1  ·ℎ  𝐷 ) ) ) )  =  ( ( 𝐴  +ℎ  ( - 1  ·ℎ  𝐶 ) )  +ℎ  ( - 1  ·ℎ  ( 𝐵  +ℎ  ( - 1  ·ℎ  𝐷 ) ) ) ) | 
						
							| 16 | 1 6 | hvaddcli | ⊢ ( 𝐴  +ℎ  ( - 1  ·ℎ  𝐵 ) )  ∈   ℋ | 
						
							| 17 | 3 8 | hvaddcli | ⊢ ( 𝐶  +ℎ  ( - 1  ·ℎ  𝐷 ) )  ∈   ℋ | 
						
							| 18 | 16 17 | hvsubvali | ⊢ ( ( 𝐴  +ℎ  ( - 1  ·ℎ  𝐵 ) )  −ℎ  ( 𝐶  +ℎ  ( - 1  ·ℎ  𝐷 ) ) )  =  ( ( 𝐴  +ℎ  ( - 1  ·ℎ  𝐵 ) )  +ℎ  ( - 1  ·ℎ  ( 𝐶  +ℎ  ( - 1  ·ℎ  𝐷 ) ) ) ) | 
						
							| 19 | 1 7 | hvaddcli | ⊢ ( 𝐴  +ℎ  ( - 1  ·ℎ  𝐶 ) )  ∈   ℋ | 
						
							| 20 | 2 8 | hvaddcli | ⊢ ( 𝐵  +ℎ  ( - 1  ·ℎ  𝐷 ) )  ∈   ℋ | 
						
							| 21 | 19 20 | hvsubvali | ⊢ ( ( 𝐴  +ℎ  ( - 1  ·ℎ  𝐶 ) )  −ℎ  ( 𝐵  +ℎ  ( - 1  ·ℎ  𝐷 ) ) )  =  ( ( 𝐴  +ℎ  ( - 1  ·ℎ  𝐶 ) )  +ℎ  ( - 1  ·ℎ  ( 𝐵  +ℎ  ( - 1  ·ℎ  𝐷 ) ) ) ) | 
						
							| 22 | 15 18 21 | 3eqtr4i | ⊢ ( ( 𝐴  +ℎ  ( - 1  ·ℎ  𝐵 ) )  −ℎ  ( 𝐶  +ℎ  ( - 1  ·ℎ  𝐷 ) ) )  =  ( ( 𝐴  +ℎ  ( - 1  ·ℎ  𝐶 ) )  −ℎ  ( 𝐵  +ℎ  ( - 1  ·ℎ  𝐷 ) ) ) | 
						
							| 23 | 1 2 | hvsubvali | ⊢ ( 𝐴  −ℎ  𝐵 )  =  ( 𝐴  +ℎ  ( - 1  ·ℎ  𝐵 ) ) | 
						
							| 24 | 3 4 | hvsubvali | ⊢ ( 𝐶  −ℎ  𝐷 )  =  ( 𝐶  +ℎ  ( - 1  ·ℎ  𝐷 ) ) | 
						
							| 25 | 23 24 | oveq12i | ⊢ ( ( 𝐴  −ℎ  𝐵 )  −ℎ  ( 𝐶  −ℎ  𝐷 ) )  =  ( ( 𝐴  +ℎ  ( - 1  ·ℎ  𝐵 ) )  −ℎ  ( 𝐶  +ℎ  ( - 1  ·ℎ  𝐷 ) ) ) | 
						
							| 26 | 1 3 | hvsubvali | ⊢ ( 𝐴  −ℎ  𝐶 )  =  ( 𝐴  +ℎ  ( - 1  ·ℎ  𝐶 ) ) | 
						
							| 27 | 2 4 | hvsubvali | ⊢ ( 𝐵  −ℎ  𝐷 )  =  ( 𝐵  +ℎ  ( - 1  ·ℎ  𝐷 ) ) | 
						
							| 28 | 26 27 | oveq12i | ⊢ ( ( 𝐴  −ℎ  𝐶 )  −ℎ  ( 𝐵  −ℎ  𝐷 ) )  =  ( ( 𝐴  +ℎ  ( - 1  ·ℎ  𝐶 ) )  −ℎ  ( 𝐵  +ℎ  ( - 1  ·ℎ  𝐷 ) ) ) | 
						
							| 29 | 22 25 28 | 3eqtr4i | ⊢ ( ( 𝐴  −ℎ  𝐵 )  −ℎ  ( 𝐶  −ℎ  𝐷 ) )  =  ( ( 𝐴  −ℎ  𝐶 )  −ℎ  ( 𝐵  −ℎ  𝐷 ) ) |