The Semantic Web vision introduces the concept of machine-oriented web information. This information is characterized by the notions of uncertainty and vagueness. Towards this notions, an ontology model for representing uncertain or vague information, as well as an inference method for reasoning about this kind of information is necessary. Our approach faces the aforementioned issues, i.e. the imperfect ontology model and the reasoning approach. In order to show how our method performs, an implementation is outlined.