## 2 Literature Review
### Reconfiguration Strategies  
Reconfiguration strategies have been used in various domains. [PERSON] et al. [25] modeled the post-disruption reconfiguration strategy as direction reversing in road networks and line switching in power networks. The authors obtained system optimal dynamic traffic assignment and optimal power flow distribution. [PERSON] et al. [26] considered reconfiguration in manufacturing systems as a combination of reassignment and replacement, in which reassignment refers to changing the positions of components without changing the component reliability. The authors obtained optimal reconfigurations with the objectives of maximum system reliability and minimum reconfiguration cost. [PERSON] et al. [27] proposed a universal redundancy strategy that can change the system structure at any time by inserting or removing redundant components individually or simultaneously. The strategy can help select the optimal reconfiguration instant, along with the optimal numbers of components to be activated or inactivated for each subsystems. [PERSON] et al. [28] considered reconfiguration as a re-arrangement of satellites in a constellation by the addition or subtraction of satellites and orbital maneuvering to achieve the desired coverage. As a summary, most reconfiguration problems have been treated as allocation/assignment problems, although the mathematical formulations demonstrate significant differences.  
In the SoS context, a number of researchers have explored the potential benefits of reconfiguration, and can be categorized into two groups. One group employs network theory to explore reconfiguration strategies. For example, [PERSON] et al. [16] employed rewiring and preferential attachment in network theory as reconfiguration strategies to achieve system resilience. The authors used simulation to compare different reconfiguration strategies. [PERSON] et al. [29; 30] proposed a cooperative reconfiguration model for unmanned swarm SoSs that allows two nodes with same function in two kill chains to work as a substitution pair. The other group employs operational-physical architecture allocation to examine the reconfiguration policies. For instance, [PERSON] and [PERSON] [31] considered reconfiguration as pro-active function-system re-tasking under \"stand-in redundancy\". [PERSON] et al. [32] pro vided an approximate dynamic programming (ADP) method to conduct function-capability re-allocation for achieving agile response under disruptions. [PERSON] et al. [33] proposed a reconfiguration method for SoSs that develops a knowledge base of adaptation strategies at the design time while generating particular adaptation strategies when receiving disruptions during the run time. Interestingly, an early study by [PERSON] and [PERSON] [34] explored the relationship between a system's architecture and reconfigurability and proposed several useful principles and guidelines for design for reconfigurability in the early design phase. Although the study focused on the system level, it offers us a deeper understanding of SoS reconfigurability.  
Reconfiguration is a promising method for improving SoS resilience and vitality, especially given the current popularity of software-defined equipment in the defense and aerospace domain. However, many questions still remain. For example, what are the optimal reconfiguration decisions for maximizing the SoS capability, what kind of architecture is more suitable for reconfiguration, and what proactive strategies are needed to realize the optimal reconfiguration? This paper aims to improve SoS resilience by developing an integrated architecture selection method to support design-time architecture selection and run-time reconfiguration decision-making.