Perturbation Methods for Abstract Cauchy Problems associated to Evolution Equations

在这个项目中，我们研究与发展方程相关的抽象柯西问题的扰动理论。许多着名的偏微分方程建模物理系统，如热方程，薛定谔方程或波动方程，使用状态的时间变化。“演化方程”是这类方程的总称，可以解释为描述系统发展的微分定律，也可以解释为对时间运动的数学处理。通过对随时间演变的系统进行建模，时间变量起着至关重要的作用，因为方程是通过平衡系统随时间的变化与其“空间”行为而建立的。通过找到演化方程的解，人们有可能预测相应物理系统的未来，这使得它成为确定性的。在理想世界中，由于系统的演化是明确给出的，因此对于给定的方程，人们将能够找到初等函数的精确解。这对从业者来说是有益的。然而，大多数真正有趣的方程不能用这种方式处理。尽管如此，研究的存在性的解决方案，其唯一性，以及定性性质作为所使用的模型的部分验证，也提供了一个基础的数值分析的方程，这是很重要的从业者。在这方面，摄动理论是一个强大的工具，并允许对这些问题的更一般和抽象的看法。一般的想法是从一个相关的和更简单的问题开始，其中的精确解是已知的。我们不仅考虑C_0-半群，而且还分别利用双连续半群和ru-连续半群来研究非强连续半群或向量格上的半群。另一方面，我们也考虑不同阶的时间依赖的非自治动力系统。

In this project we study the perturbation theory for abstract Cauchy problems associated to evolution equations. Many well-known partial differential equations modeling physical systems, such as the heat equation, the Schrödinger equation or the wave equation, use temporal change of states. "Evolution equation" is an umbrella term for such equations that can be interpreted as differential laws describing the development of a system or as a mathematical treatment of motion in time. By modeling systems evolving in time, the time variable plays a crucial role, as the equations are built by balancing the change of the system in time against its "spatial" behaviour. By finding a solution of an evolution equation one has the possibility to predict the future of the corresponding physical system which makes it deterministic. In an ideal world, one would be able to find an exact solution in terms of elementary functions for a given equation since the evolution of the system is given explicitly. This would be beneficial for practitioners. However, most of the really interesting equations cannot be treated in such a way. Nonetheless, the study of existence of solutions, their uniqueness, as well as the qualitative properties serve as a partial validation of the used models and also provides a foundation for the numerical analysis of the equation which is important for the practitioners. Perturbation theory is a powerful tool in this regard and allows for a more general and abstract view on such problems. The general idea is to start with a related and simpler problem where the exact solution is already known.On the one hand side, we study autonomous dynamical systems. We will not only consider C_0-semigroups but also non-strongly continuous semigroups or semigroups on vector lattices by means of bi-continuous semigroups and ru-continuous semigroups, respectively. On the other hand side, we also consider time-dependent and hence non-autonomous dynamical systems of different orders.