roughadj.粗糙的；粗略的，大概的；粗暴的；艰难的；讨厌的；不适的；汹涌的adv.粗糙地；粗暴地n.粗制品；暴徒；高低不平的路面vt.使粗糙；殴打；草拟rough a.粗糙的；粗暴的 draft [ dra:ft ] n.；草稿；

1. Reduction of knowledge is the core of rough set theory.
   摘要知识约简是粗糙集理论的核心问题。
2. A new method about extracting rules based on rough sets theory was proposed.
   摘要提出了一种基于粗糙集理论的规则提取的新方法。