∀ {k : Type u_1} {V1 : Type u_2} {P1 : Type u_3} [inst : Ring k] [inst_1 : AddCommGroup V1] [inst_2 : Module k V1]
  [inst_3 : AddTorsor V1 P1] (p₁ p₂ p₃ p₄ : P1) (c : k),
  (AffineMap.lineMap p₁ p₂) c -ᵥ (AffineMap.lineMap p₃ p₄) c = (AffineMap.lineMap (p₁ -ᵥ p₃) (p₂ -ᵥ p₄)) c