Edge Labelled Graphs and Property Graphs; a comparison from the user perspective
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This study compares participant acceptance of the property graph and edge-labelled graph paradigms, as represented by Cypher and the proposed extensions to the W3C standards, RDF* and SPARQL*. In general, modelling preferences are consistent across the two paradigms. When presented with location information, participants preferred to create nodes to represent cities, rather than use metadata; although the preference was less marked for Cypher. In Cypher, participants showed little difference in preference between representing dates or population size as nodes. In RDF*, this choice was not necessary since both could be represented as literals. However, there was a significant preference for using the date as metadata to describe a triple containing population size, rather than vice versa. There was no significant difference overall in accuracy of interpretation of queries in the two paradigms; although in one specific case, the use of a reverse arrow in Cypher was interpreted significantly more accurately than the ^ symbol in SPARQL. Based on our results and on the comments of participants, we make some recommendations for modellers. Techniques for reifing RDF have attracted a great deal of research. Recently, a hybrid approach, employing some of the features of property graphs, has claimed to offer an improved technique for RDF reification. Query-time reasoning is also a requirement which has prompted a number of proposed extensions to SPARQL and which is only possible to a limited extent in the property graph paradigm. Another recent development, the hypergraph paradigm enables more powerful query-time reasoning. There is a need for more research into the user acceptance of these various more powerful approaches to modelling and querying. Such research should take account of complex modelling situations.
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