“…There have been proposed many methods, such as transfer learning, domain adaptation, multitask learning [52,33,20,18,25], and meta-learning [48,5,43,2,54,49,4,9,42,21,55,11], to improve performance using data from related but different domains for regression, classification, and time-series prediction [16,44,29,41,51,1,39,40,17]. However, these methods are inapplicable for Koopman spectral analysis.…”