http://en.wikipedia.org/wiki/Convex_combination

convex combination is a linear combination of points (which can be vectors, scalars, or more generally points in an affine space) where all coefficients are non-negative and sum to 1.

흔히 하는 가중 평균(?) 형태의 조합. 이렇게 convex combination은 조합된 점들의 convex hull안에 있다는 특징이 있음.