Assembly planning is an important component for automation in manufacturing. It can help reduce the production cost by avoiding unstable subassemblies and eliminating unnecessary tool changes within the assembly cell. The assembly plan generation process begins with the exploration of the precedence relations due to geometrical and mechanical constraints. After the precedence relations are derived, all feasible assembly sequences are generated. A diamond-shape graph is commonly used to visualize all possible assembly sequences. A dual representation of all assembly sequences is also provided to facilitate the assembly sequence comparison task. Each possible sequence is transformed into a nodal representation and assumes a spatial location in a three-dimensional space. The proximity among all assembly sequence nodes in the dual space is designed to reflect the similarity among the sequences. The user can therefore navigate in the space of all feasible assembly sequences and compare similar assembly sequences that are clustered closely in the dual space. All three visualizations, namely the precedence relation, the diamond graph, and the dual graph, are coupled together so that interactions on one visualization are reflected on the other two.