INFS3101/7100 Ontology and the Semantic Web

Exercises from Week 7

For discussion in tutorial week 8-9

Key concepts from lecture: Quality principles for ontologies include clarity, coherence, extendibility, encoding bias and ontological commitment. Want to maximise the first three and minimise the last two.

1.           (relevant to points 10 and 11 of the assignment) Consider the rental accommodation exchange from the week 2 tutorial and the representation in the solution to the week 4 tutorial and following.

a.          Criticise the ontology in terms of the five principles of Gruber.

·             Clarity: suggest a plausible unintended interpretation of one of the concepts. How does (or could) the ontology prevent that unintended interpretation?

·             Coherence: suggest a plausible inference that an agent could be expected to draw from the ontology. How does (or could) the ontology support the reasoning necessary to make the inference?

·             Extendibility: suggest a plausible extension to the ontology. Show what changes would need to be made. Are any of the changes redundant? If so, show how. If not, show how the ontology design anticipated the extension.

·             Encoding bias: Show how one of the actions of week 2 might be implemented. Does it make sense for it to be implemented in a different way? If not, why not? If so, does the ontology make the different implementation difficult? Consider each element of the implementation of the action.

·             Ontological commitment: There are many different systems of interoperations in which the ontology could be reused. Describe one such system and how the ontology could be adapted to the re-use.

·             In each quality dimension, indicate whether in your judgment the quality is high or low.

b.           Propose an improvement to the ontology. Argue why this improvement is a good idea in terms of at least one of Gruber’s principles.

c.           Examine the cost and benefits of the improvement, taking into account the generality of the ontology and the number of implementations one might expect it to have. On balance, is the improvement a good idea? Take a position and justify it.