The semantic challenge for situation assessments

In relation to situation assessments in a deconstructed JDL model, one confronts the question, "What symbols should be used and how do those symbols acquire meaning?"-previously termed "the semantic challenge" for information fusion. The paper shows how meaning can be assigned to symbols by formal theories with logics because they constrain the number of possible interpretations of those symbols. Implemented examples are discussed involving ontologies, inference engines and agents. Concerning what symbols to use, the paper describes experimentation with a conceptually large military scenario. Two implementations are discussed. The first concerns an ontology and agents for semantically fusing legacy databases. The second concerns agents that receive queries through an agent grid and semantically fuse information to reply to the queries.