Subjective characterization of fuzzy target sets based on a fuzzy universe

When a subject does not have the direct observation or perfect information of the universe to characterize a target set, he needs to create a classifier on his own based on his past knowledge or experience or even wild guess. In this paper, I will give an approach to characterize a fuzzy target set via a fuzzy-universe information system. This approach allows one to characterize a target set with his own classifier induced from his own knowledge. It also gives the subject much more freedom to choose his own classifier. I also introduce several alternative characterizations for a fuzzy target set based on how confident the subject is about his knowledge regarding the universe.