“…On the other side, in item-item TBRS, the reliance of items is measured by applying users' feedback on the items [56] or studying users' activity with these items [28,57,58].However, according to the methodology of trust integration, TBRS can be categorized as memory-based [30,38,59] and model-based [20,38,60,61] approaches. Further, the TBRS can be classified based on the trust definition as either explicit [19,38,52,62] or implicit [12,13,17,18] or hybrid trust-based recommender system [35,63,64]. Figure 3 shows the classification of TBRS in a row.…”