Implement Nucleolus?

For completeness in the implementation of all methods in

_Yan, Tom, and Ariel D. Procaccia. “If You Like Shapley Then You’ll Love the Core.” In Proceedings of the 35th AAAI Conference on Artificial Intelligence, 2021. Virtual conference: Association for the Advancement of Artificial Intelligence, 2021. http://procaccia.info/wp-content/uploads/2020/12/core.pdf_

Note however, that the paper reports very poor performance, so this has low priority

该 issue 引用了用于实现 Nucleolus 方法的一篇特定学术论文。首先阅读链接的论文以理解该算法。查看库中其他方法（例如 Shapley、Core）的现有实现，以了解其模式。这项工作涉及向代码库添加一个新算法，可能位于与博弈论或数据估值方法相关的模块中。检查是否已有针对类似方法的测试，以了解测试模式。

由索引模型根据 Issue 内容生成。