An RDF Vocabulary for the Representation and Exploration of Expressions with an Illustration on Mathematical Search

Complex expressions, as used in mathematics and logics, account for a large part of human knowledge. It is therefore desirable to allow for their representation in RDF and for their exploration through semantic search. We propose an RDF vocabulary that fulfills three objectives. The first objective is the accurate representation of expressions in standard RDF, so that expressive mathematical search is made possible. We here propose a syntactic extension of Turtle and SPARQL for the concise notation of such expressions. The second objective is the automated generation of expression labels that are close to usual mathematical notations (e.g., infix operators, symbols). The third objective is the compatibility with existing practice and legacy data in the Semantic Web community for the representation of expressions and structures (e.g., OWL/RDF, SPIN). We illustrate the use of this vocabulary on mathematical search using SEWELIS, a tool for the guided exploration and edition of RDF graphs, and discuss the benefits compared to state-of-the-art in mathematical search.