“…It is a non-trivial task to retrieve the set of patents that are accurately relevant to a specific search interest, such as 3D printing and rolling robots, for the interests of engineers, designers, and innovators. The existing retrieval methods rely on keyword search in patent texts (Fujii, 2007;Koch et al, 2011;Nakamura et al, 2015) and mining additional structured information in patent documents, such as inventors, assignees, classification and citations (Wang, 2011;Benson and Magee, 2013;Song and Luo, 2017). Keyword search in patent texts is the key in general patent retrieval procedures, methods, and tools, but the keywords are often intuitively chosen by searchers subject to their knowledge and vocabulary on the technology of search interest (Fujii, 2007;Wang, 2011;Montecchi, Russo and Liu, 2013).…”