ar for abstract concepts, and a number of formally expressed, structural restrictions. Copyright c 2008, Association for the Advancement of Artificial Intelligence (www.aaai.org). All rights reserved. On the other hand, the knowledgebase (in our sense of the word) contains information with a more complex structure than what can be cleanly represented in the factbase. For example, in the domain of scientific publishing, the factbase may specify the relation between a journal and the publisher of the journal, the relation to the editorial board members, and the city where the publisher is located. The knowledgebase may e.g. contain the information about the restrictions and requirements for parallell publication that different publishers have adopted, that is, the conditions under which an author may post her article on her university's website. Knowledgebase contents are empirical in character, in the sense that it is meaningful to ask whether they are true or false, whereas the de...