1 CIS607, Fall 2005 Semantic Information Integration Presentation by Zebin Chen Week 7 (Nov. 9)

2 Questions from Homework 5 About inference approach? – Limiting the complexity of facts generated in inference, as well as the direction provided (I assume that unreasonable seeming paths are not followed) pretty much guarantees missing some valid bindings, doesn ’ t it? -- Enrico – What type of direction do you give? Is this what is going on in the backward chaining to bind variables? It seems that any fact would eventually be generated by undirected forward chaining. – Enrico – What is 'equality substitution? ‘ – Shiwoong – Could you explain forward chaining and backward chaining algorithms in more details? -- Jiawei

3 Questions from Homework 5 (cont ’ d) About the axioms? – Can the same relationship be expressed in different sets of bridging-axioms? If so, will the translated results be different? -- Dayi – How would one develop a consistency checker for bridging axioms, and what kind of techniques might it use? – Shiwoong – In page 966, (P ?x) ^ (member ? x[c1,c2,c3]) => (Q ?x). What is the meaning of backward chaining? – DongHwi – What is does logically complete mean? i.e. why isn't covering all terms from the source ontologies so that they are represented correctly in the target ontology logically complete? -- Amanda

4 Questions from Homework 5 (cont ’ d) About the OntoMerge. – Are those bridging-axioms automatically generated, or some domain experts need to write them? Can those methods for finding ontology mappings be used here (they probably can be used to generate those simple bridging-axioms)? If so, are they already plugged in or there is a plan for that? -- Dayi – In the following web site ( translation.html), we can get merged ontology of Airport ontology and Map ontology. After generating merged ontology, how can we practically use this merged ontology? -- DongHwi

5 Questions from Homework 5 (cont ’ d) Other questions about this paper: – Have you been following up on this path? Anything new and exciting along it? – Enrico – In the experiments of querying through different ontologies, do you have any experimental results -- Jiawei – So...the difference between ontology mapping and ontology merging is that ontology mapping is the correspondences between concepts in two ontologies, and ontology merging is using inference to describe more complicated correspondences between concepts in two ontologies? Or what? – Amanda – I do not yet understand the significance of generating ontology extensions. Is this an important problem with real applications? -- Paea

6 Questions from Homework 5 (cont ’ d) Other questions about this paper: – In section 1.2 is the claim: "...the querying agent doesn't need to specify which knowledge base(s) can answer it's query, it also doesn't need to know what ontologies..." But the paper also assumes that ontologies will eventually exist in large numbers. This raises some significant searching and bottleneck problems, doesn't it? The translation service has the difficult burden of identifying which ontologies apply for a given problem. If there are many ontologies, and they are distributed, then this problem is even more difficult. It reminds me of the DNS problem of networking. How will this problem be addressed? – Paea –. In section 2.2 the last two or three paragraphs make some very fundamental claims about the expressivity and power of the techniques used. Is there any theory or evidence supporting these claims? – Paea – Finally, how to you verify your results of translation or query answering? What is your criteria for success and how do you verify it? Do you just use a "gold standard" or is there a formal proof of correctness? -- Paea