for r, s being Real for V being RealLinearSpace for v being VECTOR of V for L1, L2 being Linear_Combination of V for p being Real st ((r * L1)+((1 - r)* L2)). v <= p & p <=((s * L1)+((1 - s)* L2)). v holds ex rs being Real st ( ((rs * L1)+((1 - rs)* L2)). v = p & ( r <= s implies ( r <= rs & rs <= s ) ) & ( s <= r implies ( s <= rs & rs <= r ) ) )