Enhancing Semantic Web technologies with ability to express uncertainty and imprecision is widely discussed topic. While SWRL can provide additional expressivity to OWL-based ontologies, it does not provide any way to handle uncertainty or imprecision. There is a pressing need to provide a standard-based, simple and functioning solution. We describe an extension of SWRL called SWRL-F that we believe can provides such a solution. SWRL-F is based on SWRL rule language and uses SWRL’s strong semantic foundation as its formal underpinning. We extend it with a SWRL-F ontology to enable fuzzy reasoning in the rule base basing on the fuzzy control systems approach. The resulting language provides small but powerful set of fuzzy operations that do not introduce inconsistencies in the host ontology. We present it basing on the example of risk assessment in oil and gas industry which was a driving use case for this project.
