|This article relies largely or entirely upon a single source. (March 2011)|
GraSM (Graph-based Similarity Measure) is a method for incorporating the semantic richness of a graph in semantic similarity measures by selecting disjunctive common ancestors of two concepts. GraSM assumes that two common ancestors are disjunctive if there are independent paths from both ancestors to the concept. In 2011, the authors of GraSM proposed the method DiShIn with a higher computational efficiency and a more solid management of parallel interpretations.
metal / \ precious coinage / | \ / \ palladium platinum gold copper
When calculating the semantic similarity between platinum and gold, most topological measures only use their most informative common ancestor, in this case precious. On the other hand, GraSM takes also in account the following independent paths to metal:
gold -> coinage -> metal platinum -> precious -> metal
Thus, GraSM defines the similarity between platinum and gold proportional to the average of the information content of their common disjunctive ancestors: metal and precious; and the similarity between platinum and palladium only proportional to the information content of precious, since there are no independent paths from them to metal.
This means that for GraSM palladium and platinum are more similar than platinum and gold, since gold can have another interpretation.
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