Page 75 - Trust in ICT 2017

Trust in ICT 1

expectations), TrustProfile (trust guarantees), TrustAttribute, Measurable TrustAttribute and
NonMeasurable TrustAttribute.

Figure 20 – Trust ontology [77]
Semantic Matchers

Discovery of the trustworthy products is a semantic matching or semantic search task. The trust expectations
of a user are semantically matched with the trust guarantees of a service/product. The trust expectations
and guarantees may match exactly, almost or be disjoint. If the trust guarantees match the trust expectations
exactly or almost, the product classifies as trustworthy. If disjoint, the product classifies as distrusted. With
the trust expectations and trust guarantees expressions communalized and formalized using semantic
vocabularies and machine-processable semantic annotations, the trust-based discovery engines will be
capable to do better job, thanks to the semantics.
There are many existing semantic matchers and semantic search engines available. The existing ones can be
reused to develop a special-purpose engine for matching the trust expectations with trust guarantees. In
particular [77] have developed a trust evaluation module on the top of a trust goal classification approach
introduced in [78], which was designed for the trust-based discovery of semantic web services. In that
approach, trust guarantees of the web services are matched against trust expectations by a classification
technique to identify services that fit (classify) into the requirement. In addition to the classification, they
have introduced the measure of similarity between the trust expectations and trust guarantees. The measure
is a value between 0 and 1, and represents the trust level.

Importantly, the trust guarantees should be constantly or periodically verified and monitored, by users
and/or by established central authorities, in order to help to increase accuracy of the trust evaluation. The
monitoring is collecting the evidence for the claimed trust guarantees. The monitoring of trust guarantees
requires sophisticated mechanisms over the Internet with possible involvement of trusted third parties for
detecting, isolating and limiting the negative behaviours. It is a challenge on its own.

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