Understanding and using the data and knowledge encoded in semantic web documents requires an inference engine . F - OWL is an inference engine for the semantic web language OWL language based on F - logic , an approach to defining frame - based systems in logic . F - OWL is implemented using XSB and Flora-2 and takes full advantage of their features . We describe how F - OWL computes ontology entailment and compare it with other description logic based approaches . We also describe TAGA , a trading agent environment that we have used as a test bed for F - OWL and to explore how multiagent systems can use semantic web concepts and technology .