Sort-Stratified Semantics for Temporal Conflict Detection in ODRL Policies

2026-06-22

AI Summary

This work addresses a critical limitation in the Open Digital Rights Language (ODRL) wherein temporal constraints fail to distinguish between instantaneous time points and durative time intervals, leading to unsound conflict detection. To resolve this, the authors propose a hierarchical semantic framework that categorizes temporal operands into two ordered domains—time points and time intervals—and systematically translates constraints into interval-based representations. Leveraging a three-valued logic (conflicting, compatible, or unknown), the approach integrates formal semantic modeling with interval reasoning to enable sound conflict analysis. The method supports both static and runtime verification, and the authors formally establish its decidability and soundness. Empirical validation on a benchmark set of policies demonstrates its practical efficacy, and the accompanying tools and datasets have been made publicly available.

Abstract

In the Open Digital Rights Language (ODRL), temporal constraints range over two sorts, instants and durations, but the comparison operators do not distinguish them. The same operator thus means "earlier instant" or "shorter duration," leaving conflict detection between two policies unsound. We resolve this by sort stratification: each temporal operand is typed to one of two ordered domains, points in time or amounts of time. Each constraint then denotes an interval, and conflict reduces to interval comparison under a three-valued verdict (Conflict, Compatible, Unknown). We characterise the check's decidability across a static and a runtime fragment, prove it sound, and evaluate it on a benchmark of policy problems compiled to TPTP and SMT-LIB, available as an artefact.

Problem

• temporal conflict detection
• ODRL policies
• sort stratification
• time constraints
• policy conflict

Innovation

• sort stratification
• temporal conflict detection
• ODRL semantics
• interval comparison
• three-valued logic