OLG++: A Semantic Extension of Obligation Logic Graph

TL;DR

OLG++ is a semantic extension of Obligation Logic Graph that enhances legal rule modeling with richer constructs, enabling nuanced reasoning and improved expressiveness over prior models, demonstrated through legal regulation examples.

Contribution

Introduces OLG++, a semantic extension of OLG with advanced node and edge types for detailed legal rule representation and reasoning.

Findings

Supports complex legal rule modeling with spatial, temporal, and defeasibility constructs.

Enables legal question answering using property graph queries.

Offers greater expressiveness than prior graph-based legal models.

Abstract

We present OLG++, a semantic extension of the Obligation Logic Graph (OLG) for modeling regulatory and legal rules in municipal and interjurisdictional contexts. OLG++ introduces richer node and edge types, including spatial, temporal, party group, defeasibility, and logical grouping constructs, enabling nuanced representations of legal obligations, exceptions, and hierarchies. The model supports structured reasoning over rules with contextual conditions, precedence, and complex triggers. We demonstrate its expressiveness through examples from food business regulations, showing how OLG++ supports legal question answering using property graph queries. OLG++ also improves over LegalRuleML by providing native support for subClassOf, spatial constraints, and reified exception structures. Our examples show that OLG++ is more expressive than prior graph-based models for legal knowledge representation.