That is, take a complete flag (say the standard flag) 0 = V0 < V1 <...< Vn; then the closed k-cell is lines that lie in Vk.
这便是，取一个完全旗（称为标准旗）0 = V0 < V1 <...< Vn；则闭 k-胞腔是属于 Vk 中的直线。