我们研究里奇流非紧孤立子的几何与分析性质， 特别关注那些在研究短时间Ricci流奇异点的过程中自然出现的非紧孤立子。在四维的时候，我们期望对这样的非紧收缩孤立子的无穷远性质有更加深刻的了解。 基于这些了解, 我们最终会得到一个关于四维非紧收缩孤立子的分类定理。这将会极大地提升人们对四维 Ricci流的理解。

We study the geometric and analytic properties of the noncompact Ricci shrinkers. In particular, we focus on the shrinkers which appear naturally in the formation of short time singularities of the Ricci flow. When the dimension is four, we expect to obtain much deeper understanding of the infinity structure of the shrinkers. Based on such understanding, we shall finally obtain a complete classification of such Ricci shrinkers. This study will greatly improve our understanding of four dimensional Ricci flow.