On Subjective Logic Trust Discount for Referral Paths

Subjective Logic (SL) enriches probabilistic logic by incorporating uncertainty and subjective belief ownership, enabling the expression of uncertainty about subjective beliefs. Unlike traditional probabilistic logics, SL 1) accommodates situations where different agents express beliefs about the same proposition, integrating the subjective nature and ownership of beliefs; and 2) addresses existing limitations in Dempster-Shafer Theory of evidence (DST), particularly in modelling trust transitivity. In modern computer systems, trust assessment extends beyond direct relationships to complex networks, necessitating the consideration of referral and direct trust relationships. This paper introduces a novel trust discount operator for referral edges in complex networks, addressing challenges in discounting trust across two and multiple referral edges. Through our empirical analysis, we demonstrate the effectiveness of the proposed operator and establish a relationship between path length and trustworthiness.