The multiset semantics of SPARQL patterns

TL;DR

This paper characterizes the algebraic and logical structure of SPARQL's core patterns under multiset semantics, linking them to multiset relational algebra and non-recursive Datalog with safe negation.

Contribution

It establishes a formal correspondence between SPARQL core patterns and well-known algebraic and logical frameworks, clarifying their theoretical foundations.

Findings

SPARQL core patterns correspond to multiset relational algebra

They also align with multiset non-recursive Datalog with safe negation

Provides a formal basis for understanding SPARQL semantics

Abstract

The paper determines the algebraic and logic structure of the multiset semantics of the core patterns of SPARQL. We prove that the fragment formed by AND, UNION, OPTIONAL, FILTER, MINUS and SELECT corresponds precisely to both, the intuitive multiset relational algebra (projection, selection, natural join, arithmetic union and except), and the multiset non-recursive Datalog with safe negation.