标题： 2-范畴理论中的Lax结构 显示英文标题

标题： Lax structures in 2-category theory

摘要： 本论文专注于2-范畴理论的主题：特别是双重范畴、伪单子和码升对象。 在第2章中我们回顾了所有必要的概念。 在第3章中我们展示了可以将因子系统等价地描述为满足某些性质的双重范畴。 在第4章中我们关注以通用方式将弱（次共变）结构转变为严格结构——这包括例如次共变单子范畴或次函子。 在第5章中我们研究了一个次幂等伪单子的Kleisli 2-范畴，其应用在于建立诸如单子范畴和次单子函子这类2-范畴的弱余完备性。 最后，在第6章中我们关注如何将任意2-单子转变为次幂等的。 显示英文摘要

摘要： This thesis focuses on topics in 2-category theory: in particular on double categories, pseudomonads and codescent objects. In Chapter 2 we recall all the necessary notions. In Chapter 3 we show that factorization systems can be equivalently described as double categories satisfying certain properties. In Chapter 4 we focus on turning weak (colax) structures into strict ones in a universal way - this covers for instance colax monoidal categories or lax functors. In Chapter 5 we study the Kleisli 2-category for a lax-idempotent pseudomonad, the application of which is establishing weak cocompleteness of 2-categories such as the one of monoidal categories and lax monoidal functors. Finally, Chapter 6 focuses on the process of turning any 2-monad into a lax-idempotent one.