Reasoning Methods in Semantic Web

Semantic Web is a collection of different technologies, where most of them is already standardized. The main purpose of these technologies is to describe semantic content of the web, i.e. their meaning and sense, in the format understood by computers. As a consequence, computer programs will be able to use more (human) knowledge to do assigned tasks. In this paper we overview the ontology and logic layers of the semantic web stack. Although ontology languages are standardized by W3C, there are still many problems remaining, which are related to reasoning over the ontologies. On the logic layer of the semantic web stack are considered unranked languages, where function and predicate symbols do not have a fixed arity. Such languages can naturally model XML documents and operations on them. In this paper we present survey of reasoning methods over such unranked languages.