∀ (𝕜 : Type u_1) {E : Type u_2} {G : Type u_4} [inst : Ring 𝕜] [inst_1 : PartialOrder 𝕜] [AddRightMono 𝕜]
  [inst_3 : AddCommGroup E] [inst_4 : AddCommGroup G] [inst_5 : Module 𝕜 E] [inst_6 : AddTorsor G E]
  [VAddCommClass G E E] (a : G) (b c : E), openSegment 𝕜 (a +ᵥ b) (a +ᵥ c) = a +ᵥ openSegment 𝕜 b c