Representing Time for the Semantic Web

Representation of temporal information for the Semantic Web often involves qualitative defined information (i.e., information described using natural language terms such as "before"), since precise dates are not always available in addition to quantitative defined temporal information. This work proposes several representations for time points and intervals in ontologies by means of OWL properties and reasoning rules in SWRL embedded into the ontology. Although qualitative representations for interval and point relations exist, in addition to quantitative ones, this is the first work proposing representations combining qualitative and quantitative information for the Semantic Web. In addition to this, several existing and proposed approaches are compared using different reasoners and experimental results are presented in detail. Experimental results illustrate that reasoning performance differs greatly between different representations and reasoners. To the best of our knowledge this is the first such experimental evaluation of both qualitative and quantitative Semantic Web temporal representations.