January 2012 Volume 15 Number 1 - Educational Technology ...

Ontology-Based Reasoning
The inference agent depends on semantics of SoPro ontology and cu-2’s LOM to reason the following facts.
1. The cu-2 learning object is an instance of XHTML class (see row 2 of Table 1).
2. There is a standard relation from cu-2 to cu-1 (see row 1 of Table 2).
3. The application property is an inverse of standard property.
Base on the above facts, inference agent can reason that there is an application relation from cu-1 to cu-2. The
inference result is converted to an LOM document, as shown in Figure 6. The output result of ontology-based
reasoning is shown in (B) of Figure 4.
Rule-based Inference
……………….
URI
http://sparc.nfu.edu.tw/~hsuic/sw/ontology/SoPro.owl#XML
URI
http://sparc.nfu.edu.tw/~hsuic/sw/ontology/SoPro.owl#application
learning object ID
cu-2
…………………
Figure 6. The ontology-based metadata created by inference agent
This inference agent relies on the previous inference results, LOM-based metadata documents and RuleML rules to
perform the following tasks.
1. It converts the relation metadata of LOMs (see Table 2) and previous inference results (see Figure 6) to JESSbased
facts, as shown in Figure 7.
(assert
(triple (predicate "http://sparc.nfu.edu.tw/~hsuic/sw/ontology/SoPro.owl#standard ")
(subject "cu-2") (object "cu-1")))
(assert
(triple (predicate "http://sparc.nfu.edu.tw/~hsuic/sw/ontology/SoPro.owl#application")
(subject "cu-1") (object "cu-2")))
(assert
(triple (predicate "http://sparc.nfu.edu.tw/~hsuic/sw/ontology/SoPro.owl# XMLParser ")
(subject "cu-1") (object "cu-4")))
(assert
(triple (predicate "http://sparc.nfu.edu.tw/~hsuic/sw/ontology/SoPro.owl#using")
(subject "cu-4") (object "cu-3")))
Figure 7. The relation metadata are converted to JESS-based facts
2. It converts the RuleML rule (see Example 4) to JESS-based rule, as shown in Figure 8.
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