ODRL Policy Comparison Through Normalisation

arXiv cs.AI / 3/16/2026

📰 NewsIdeas & Deep AnalysisModels & Research

共有:

Key Points

The paper addresses the complexity and lack of interoperability in ODRL policies by focusing on semantically equivalent policies expressed in multiple fragments.
It introduces a parametrised normalisation approach that reduces policies to minimal components, converting prohibitions into permissions and simplifying complex constraints.
The authors provide algorithms to compute a normal form while proving semantic preservation, and they analyze size complexity as exponential in the number of attributes and linear in the number of unique attribute values.
The work demonstrates that complex policies can be represented in simpler ODRL fragments and that policy comparison is reduced to checking whether two rules are identical.

Abstract

The ODRL language has become the standard for representing policies and regulations for digital rights. However its complexity is a barrier to its usage, which has caused many related theoretical and practical works to focus on different, and not interoperable, fragments of ODRL. Moreover, semantically equivalent policies can be expressed in numerous different ways, which makes comparing them and processing them harder. Building on top of a recently defined semantics, we tackle these problems by proposing an approach that involves a parametrised normalisation of ODRL policies into its minimal components which reformulates policies with permissions and prohibitions into policies with permissions exclusively, and simplifies complex logic constraints into simple ones. We provide algorithms to compute a normal form for ODRL policies and simplifying numerical and symbolic constraints. We prove that these algorithms preserve the semantics of policies, and analyse the size complexity of the result, which is exponential on the number of attributes and linear on the number of unique values for these attributes. We show how this makes complex policies representable in more basic fragments of ODRL, and how it reduces the problem of policy comparison to the simpler problem of checking if two rules are identical.