English
If p lies in the affine span of ps, inserting p into ps does not change the span.
Русский
Если p принадлежит аффинной оболочке ps, добавление p в ps не изменяет оболочку.
LaTeX
$$$p \in \operatorname{affineSpan}(k, ps) \Rightarrow \operatorname{affineSpan}(k, \operatorname{insert } p ps) = \operatorname{affineSpan}(k, ps).$$$
Lean4
/-- One line is contained in another differing in the second point if the second point of the
first line is contained in the second line. -/
theorem affineSpan_pair_le_of_right_mem {p₁ p₂ p₃ : P} (h : p₁ ∈ line[k, p₂, p₃]) : line[k, p₂, p₁] ≤ line[k, p₂, p₃] :=
affineSpan_pair_le_of_mem_of_mem (left_mem_affineSpan_pair _ _ _) h