## 2 Literature Review  
### Product Representation and Modeling Methods in Manufacturing  
The mainstream product representation and modeling approaches of ASPO and DSPO in manufacturing can be categorized into four varieties: graph-based modeling, AND/OR graph modeling, Petri net (PN) modeling, and matrix-based modeling methods, respectively. The graph-based modeling is a method that utilizes a directed or undirected graph composed of nodes and edges to depict the precedence relationship among components, mainly based on graph theory [8]. [PERSON] et al. [17] implemented a liaison graph to express the connection relationships between parts of a fixed support holder. [PERSON] et al. [18] employed the disassembly hybrid graph to describe the hierarchical information and constraint relations between the product components. Different from the graph-based modeling, the AND/OR graph is applied to graphically represent all possible disassembly sequences of the given disassembly operations or components/parts [12]. [PERSON] et al. [19] used the AND/OR graph to handle a novel dual-objective disassembly problem from economic and energy-efficient perspectives, and the effectiveness has been validated. The Petri net is a graphical and mathematical technique suitable for modeling and analyzing information processing systems [20]. With an initial state called the initial marking, the directed graph consists of two kinds of nodes, called places and transitions, which are connected via arcs [21]. [PERSON] and [PERSON] [14] combined the disassembly Petri Net with a hybrid Bayesian network to model the disassembly process and predict the outcome of each disassembly action.  
Generally, graph-based product descriptions need to be converted into matrix-based representations for computer processing [8]. The matrices depict the characteristics of a product from three perspectives: precedence relationships, connection relationships, and interference relationships among components. [PERSON] et al. [22] adopted five matrices: a contact constraint matrix for components, a motion constraint matrix for components, a contact constraint matrix for fasteners, a motion constraint matrix for fasteners, and a projection matrix for components. [PERSON] et al. [23] put up with an omnidirectional geometrical feasibility matrix to represent the conditions in the actual disassembly environment. [PERSON] et al. [24] proposed the 'assembly matrix' as a fundamental tool to interpret a physical assembly and then derived three new matrices: a contact matrix, a space interference matrix, and a relation matrix.  
Compared with a mechanical product, the ASPO of prefabricated components is less complex due to the topological relationships among prefabricated components being solely formed by connection without precedence. An unreasonable assembly sequence might increase installation difficulty for precast components, but for a mechanical product, it may cause assembly failure and rework. Therefore, with appropriate simplification and modification, these modeling methods are competent to deal with the assembly in prefabricated construction. By contrasting the four modeling methods, the matrix-based modeling method is the most computer-friendly and more suitable for prefabricated components.