“…In relation to the study of this topic, several approaches have been used as follows: in case a Cartesian product (or digital product) has a normal adjacency in [11] (or an S-compatible adjacency in [27], or the L S -property [23]) or the L C -property in [21], many works including [6,20,23,26] dealt with digital topological properties of digital products by using a digital fundamental group [4], digital coverings [10,11,25], an automorphism group of a digital covering [18] and a digital k-surface structure [2,3,8,14,31]. Computing Hyper-crossed complex pairings in digital images was studied in [35]. However, these approaches could not be enough to deal with the issue because the other cases remain open.…”