It is known that poset theory is important to the study on greedoid theory.But what is the direct relation between poset theory and the containment relations between different kinds of greedoids?

• 众所周知；偏序集理论在研究广义拟阵论中起着重要作用.；但是偏序集理论与不同种广义拟阵间的包含关系的直接联系是什么呢?