“…Modern society has witnessed an enormous progress in collecting all kinds of data with complex structures, and datasets in the form of tensors have been increasingly encountered from many fields, such as signal processing (Zhao et al, 2012;Shimoda et al, 2012), medical imaging analysis (Zhou et al, 2013;Li et al, 2018), economics and finance (Chen et al, 2022;Wang et al, 2021b), digital marketing (Hao et al, 2021;Bi et al, 2018) and many others. Many unsupervised learning methods have been considered for these datasets, and they include the principal component analysis (Zhang and Ng, 2022), clustering (Sun and Li, 2019;Luo and Zhang, 2022), and factor modeling (Bi et al, 2018;Chen et al, 2022). On the other hand, there is a bigger literature for analyzing tensor-valued observations with supervised learning methods, and most of them come from the area of machine learning by using neural networks (Novikov et al, 2015;Kossaifi et al, 2020).…”