“…For example, the pioneering trust metric Eigen-Trust [Kamvar et al 2003] defined the direct trust for a pair of transacted participants using binary rating {-1, +1}, tr (p i , p j )=-1 denoted a negative rating from p i to p j , and tr (p i , p j )=+1 represented a positive rating. The heritage EigenTrust ++ [Fan et al 2012] and GroupTrust [Fan et al 2017], both employed this kind of binary rating. Differently, ServiceTrust [Su et al 2013] and ServiceTrust ++ [Su et al 2015] utilized the multiscale rating {-1, 0, 1, 2, 3, 4, 5} indicating bad, no-rating, neutral, fair, good, very good and excellent query transaction respectively.…”