https://yestino.com/zh-CN/entities/kids-0c1df2与 Kids 相关的全部事件zh-CNhttps://yestino.com/zh-CN/events/category-theory-for-kids-405d59https://yestino.com/zh-CN/events/category-theory-for-kids-405d59Tue, 25 Aug 2026 22:01:42 GMTIn mathematics , a category is like a special collection of "things" (called objects ) that are connected by "links" (called arrows or morphisms ). 来源：Hacker News