通常，这样的线性序列称为满足拓扑次序(Topological Order)的序列，简称拓扑序列。简单的说，由某个集合上的一个偏序得到该集合上的一个全序，这个操作称之为拓扑排序。-Typically, such a linear sequence called meet topological order (Topological Order) sequence, referred to topological sequence. Simply put, by a partial order on a collection of a total order on the collection, this operation is called topological sorting.