Abstract: With the development and recent research of three-way decisions (3WD), this paper proposes generalized three-way decisions and special three-way decisions based on the models, algorithms and applications of 3WD at first. Generalized three-way decisions focus on illustrating the intension and extension of 3WD; and special three-way decisions take attention to the semantic interpretation of 3WD in real decision problems. Then, this paper presents a “four-level” three-way granular structure decision model. In order to clarify the development process and research context of 3WD, this paper uses two viewpoints (static and dynamic viewpoint, generalized and special viewpoint) to analyze 3WD. Finally, this paper gives the research status and future research directions of 3WD.

Key words: three-way decisions, decision-theoretic rough sets, generalized three-way decisions, special three-way   , decisions

摘要： 从三支决策发展历史出发，在总结三支决策近年来研究的基础上，基于三支决策现有模型、算法及应用，提出了一种广义三支决策和狭义三支决策理论。广义三支决策注重对三支决策概念内涵和外延进行诠释；狭义三支决策主要注重三支决策在实际决策问题中的语义解释。提出了一种“四层次”三支粒结构决策模型，从静态和动态、广义和狭义两种视角对三支决策进行剖析，厘清了三支决策发展过程和研究脉络。最后，给出了三支决策的研究现状和未来发展方向。

关键词: 三支决策, 决策粗糙集, 广义三支决策, 狭义三支决策