标题： 在朴素离散同伦理论中极限的不存在性 显示英文标题

标题： Nonexistence of colimits in naive discrete homotopy theory

摘要： 我们证明，将图的范畴在A-同伦等价类处进行局部化所定义的准范畴不包含余极限。特别是，我们以否定方式解决了图的范畴中的A-同伦等价是否属于一个模型结构的问题。 显示英文摘要

摘要： We show that the quasicategory defined as the localization of the category of (simple) graphs at the class of A-homotopy equivalences does not admit colimits. In particular, we settle in the negative the question of whether the A-homotopy equivalences in the category of graphs are part of a model structure.