Propagation of trust and distrust
R. GuhaRavi KumarPrabhakar RaghavanAndrew Tomkins
Develops a matrix-based framework for propagating both positive trust and negative distrust across social networks, proving on large-scale real-world data that even sparse ratings can accurately predict interpersonal trust.
Online platforms and e-commerce systems face significant challenges in filtering low-quality information, malicious reviews, and fraudulent behavior. While reputation networks can help users assess the trustworthiness of others, real-world trust graphs are highly sparse, meaning most individuals rate only a small number of peers. The article develops and evaluates a computational framework designed to accurately predict pairwise trust and distrust scores across sparse social networks.
To test this framework, the authors conducted an empirical study using real-world data from the review platform Epinions, comprising approximately 841,000 trust and distrust relationships across 131,000 users. The evaluation tested 81 combinations of computational approaches using cross-validation over thousands of masked connections. The framework varied the propagation patterns (direct links, shared citations, reciprocation, and coupled trust), distrust handling mechanisms, numerical iteration strategies, and methods for converting continuous trust scores back into binary decisions.
Key findings show that pairwise trust can be inferred with high accuracy even from sparse network data. The best-performing approach reduced prediction error to 6.4% on random evaluation links and 14.7% on a balanced dataset of equal trust and distrust instances, outperforming the baseline error rate of 50%. Incorporating distrust was critical: treating distrust as propagating a single step—discounting the immediate judgments of distrusted parties rather than chaining distrust across multiple hops—yielded the strongest predictive power. Combining direct connections with indirect network patterns, such as co-citation, substantially outperformed relying on direct trust chains alone. Additionally, local neighborhood rounding methods proved decisive in accurately translating calculated scores into discrete ratings.
These findings indicate that digital marketplaces and community platforms can strengthen content integrity, reduce fraudulent manipulation, and improve personalized recommendations without requiring extensive user rating history. Contrary to common assumptions, modeling distrust requires different mathematical properties than positive trust, as transitive negative chains create distortion. Platforms that actively incorporate distrust signals can significantly improve safety and content filtering compared to systems relying solely on positive feedback.
Organizations implementing web-of-trust frameworks should deploy models that integrate multiple relationship structures, restrict distrust propagation to single-step discounting, and utilize local majority-based rounding. Further research and piloting should explore how these methods perform on other online network topologies, as well as test additive rather than multiplicative models for chaining distrust across larger communities.
- Paper: The Eigentrust algorithm for reputation management in P2P networks, Sepandar D. Kamvar et al. (2003). EigenTrust established iterative matrix-based propagation of global trust scores across sparse networks, providing the foundational mathematical framework that the source paper adapts and contrasts when handling distrust.
- Paper: The link prediction problem for social networks, David Liben-Nowell et al. (2003). This work formalized link prediction and proximity metrics (including co-citation and multi-hop paths) in social graphs, which the source paper directly applies to infer pairwise trust and distrust.
- Paper: SimRank: a measure of structural-context similarity, Glen Jeh et al. (2002). SimRank introduced structural context and co-citation similarity propagation over arbitrary graphs, directly informing the propagation patterns evaluated in the source paper.
- Paper: Mining knowledge-sharing sites for viral marketing, Matthew Richardson et al. (2002). This study pioneered the extraction and linear modeling of trust networks using the Epinions platform data, establishing the primary empirical testbed used by the source paper.
- Paper: Predicting positive and negative links in online social networks, Jure Leskovec et al. (2010). This paper extends the study of signed social networks by evaluating supervised learning over local structural balance and status theories to predict positive and negative edges on Epinions and other graphs.
- Paper: A matrix factorization technique with trust propagation for recommendation in social networks, Mohsen Jamali et al. (2010). This research builds upon network-based trust propagation by integrating multi-step trust influence directly into matrix factorization models for recommendation.
- Paper: Recommender systems with social regularization, Hao Ma et al. (2011). This work extends trust and social network modeling into collaborative filtering through explicit social regularization constraints on matrix factorization.
- Paper: Graph Neural Networks for Social Recommendation, Wenqi Fan et al. (2019). GraphRec modernizes social trust modeling by utilizing graph neural networks to jointly capture user-user trust and user-item interactions on platforms like Epinions.
