Support + Belief = Decision Trust
Alessandro Aldini, Agata Ciabattoni, Dominik Pichler, Mirko Tagliaferri
TL;DR
SBTrust introduces a unified logical framework for decision trust by combining a belief modality with a novel non-monotonic support operator. The support connective, interpreted via preference-based semantics, captures when one statement most likely supports another, while belief anchors subjective truth, yielding a trust operator Tφψ that requires both φ and φ supports ψ to hold. The paper provides syntax, semantics, and proof theory, and shows SBTrust is sound, complete, and PSPACE-complete for satisfiability, with tractable model checking. By connecting to KLM and Åqvist FA84 and allowing multiple support systems via trust frames, SBTrust offers a flexible, integrative approach to reasoning about trust across cognitive, policy, and reputation factors. The framework lays groundwork for future extensions such as nesting, proofs, and dynamic multi-agent settings, broadening applicability to complex, real-world trust environments.
Abstract
We present SBTrust, a logical framework designed to formalize decision trust. Our logic integrates a doxastic modality with a novel non-monotonic conditional operator that establishes a positive support relation between statements, and is closely related to a known dyadic deontic modality. For SBTrust, we provide semantics, proof theory and complexity results, as well as motivating examples. Compared to existing approaches, our framework seamlessly accommodates the integration of multiple factors in the emergence of trust.