Partially ordered set
“partially ordered set”即“偏序集”。
维基百科Partially ordered set
笔记
Partial order VS total order
在原文中的对一段中对这个问题进行了详细分析。
Partial order的 reflexive 的思考？
在原文第二段中：
Formally, a partial order is any binary relation that is reflexive (each element is comparable to itself), antisymmetric (no two different elements precede each other), and transitive (the start of a chain of precedence relations must precede the end of the chain).
其中强调了partial order需要是 reflexive ，但是第三段中所枚举的 genealogical descendancy 显然是不具备 reflexive 的。