On foundational aspects of RDF and SPARQL

TL;DR

This paper introduces a category theory-based formal framework for RDF and SPARQL, clarifying their core features and semantics through algebraic graph transformations, enhancing understanding of blank nodes and query operations.

Contribution

It presents a novel categorical and algebraic framework for RDF and SPARQL, providing formal definitions and semantics that improve conceptual clarity.

Findings

Formal definitions of RDF graphs and SPARQL patterns using category theory

Clarification of blank nodes' roles in RDF and SPARQL

Operational semantics for SPARQL queries via POIM algebraic graph transformations

Abstract

We consider the recommendations of the World Wide Web Consortium (W3C) about the Resource Description Framework (RDF) and the associated query language SPARQL. We propose a new formal framework based on category theory which provides clear and concise formal definitions of the main basic features of RDF and SPARQL. We propose to define the notions of RDF graphs as well as SPARQL basic graph patterns as objects of some nested categories. This allows one to clarify, in particular, the role of blank nodes. Furthermore, we consider basic SPARQL CONSTRUCT and SELECT queries and formalize their operational semantics following a novel algebraic graph transformation approach called POIM.