1 Berendt: Advanced databases, first semester 2011, 1 Advanced databases – Inferring new knowledge from data(bases): Some observations about problems with deductive reasoning and inconsistencies, and with other data- quality problems, in HW 1 and 2 Bettina Berendt Katholieke Universiteit Leuven, Department of Computer Science Last update: 6 December 2011

2 Berendt: Advanced databases, first semester 2011, 2 Common issues in HW1 and HW2 (1) n Intended differences between UML/ER model and OWL ontology l „Semantic“ differences vs. Differences due to expressivity l Attention: look at constraints! l TODO: describe which is which (and why) n Unintended differences between UML/ER model and OWL ontology l Cardinality/multiplicity restrictions l TODO: check for each one, add where applicable n (This occurred mainly when there were „semantic“ differences“): subclass vs. Instance l HEURISTIC: ? l TODO: ?

3 Berendt: Advanced databases, first semester 2011, 3 Common issues in HW1 and HW2 (2) Inconsistent ontologies n Cardinality constraints violated l TODO: ? n Missing data in the data source l TODO: ? n Datatype incompatibilities l TODO: ? n Axioms violated l TODO: ? n Own ontology not uploaded, but recreated (with divergences9 l TODO: ? n Outlook: inconsistent data l TODO: ?

4 Berendt: Advanced databases, first semester 2011, 4 Common issues in HW1 and HW2 (3) n The reasoner does not infer what it should do l EXPLANATION (I think): inadequate usage of sufficient and necessary conditions [cf. Pizza Tutorial] l TODO: ?