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DiShIn (Disjunctive Shared Information) is a method for exploitation of multiple inheritance when calculating the shared information content between two ontological concepts being compared by node-based semantic similarity measures. DiShIn re-defines the shared information content between two concepts as the average of all their disjunctive ancestors, assuming that an ancestor is disjunctive if the difference between the number of distinct paths from the concepts to it is different from that of any other more informative ancestor. In other words, a disjunctive ancestor is the most informative ancestor representing a given set of parallel interpretations. DiShIn is an improvement of GraSM in terms of computational efficiency and in the management of parallel interpretations. == Example == For example, palladium, platinum, silver and gold are considered to be precious metals, and silver, gold and copper considered to be coinage metals. Thus, we have: metal / \ precious coinage / | \ \ / / \ / | \ gold / \ palladium platinum silver copper When calculating the semantic similarity between ''platinum'' and ''gold'', DiShIn starts by calculating the number of paths difference for all their common ancestors: gold -> coinage -> metal gold -> precious -> metal platinum -> precious -> metal gold -> precious platinum -> precious For ''metal'' we have two paths from ''gold'' and one from ''platinum'', so we have a path difference of one. For ''precious'' we have one path from each concept, so we have a path difference of zero. Since their path difference is distinct, both common ancestors ''metal'' and ''precious'' are considered to be disjunctive common ancestors. When calculating the semantic similarity between ''platinum'' and ''palladium'', DiShIn starts by calculating the number of paths difference for all their common ancestors: palladium -> precious -> metal platinum -> precious -> metal palladium -> precious platinum -> precious For both ''metal'' and ''precious'', we have only one path from each concept, so we have a path difference of zero for both common ancestors. Thus, only the common ancestor ''precious'' (the most informative) is considered to be a disjunctive common ancestor. Given that node-based semantic similarity measures are proportional to the average of the information content of their common disjunctive ancestors: ''metal'' and ''precious'' in case of ''platinum'' and ''gold''; and ''precious'' in case of ''platinum'' and ''palladium'', means that for DiShIn ''palladium'' and ''platinum'' are more similar than ''platinum'' and ''gold''. When calculating the semantic similarity between ''silver'' and ''gold'', DiShIn starts by calculating the number of paths difference for all their common ancestors: gold -> coinage -> metal gold -> precious -> metal silver -> coinage -> metal silver -> precious -> metal gold -> precious silver -> precious gold -> coinage silver -> coinage As in the case of ''platinum'' and ''palladium'', here all common ancestors have a path difference of zero, since ''silver'' and ''gold'' share the same relationships and therefore have parallel interpretations. Thus, only the most informative common ancestor ''precious'' or ''coinage'' is considered to be a disjunctive common ancestor. This means that for DiShIn the similarity between ''silver'' and ''gold'' is greater or equal than the similarity between any other pair of the leaf concepts. Thus, DiShIn does not penalize parallel interpretations as GraSM did. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「DiShIn」の詳細全文を読む スポンサード リンク
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