Dynamic vs Static

A Semantic Web Primer for Object-Oriented Software Developers "In contrast to object-oriented systems, where objects normally cannot change their type, applications based on Semantic Web technology can follow a formal, yet dynamic typing system. RDF and OWL classes themselves are also dynamic, it is possible to create and manipulate them at runtime. For example, one could define a temporary class that is formally represented as an OWL expression and then ask the reasoner about the instances of this class. This means that reasoners can be compared to rich query answering systems. These queries can not only be asked at ontology design time, but also at execution time."