Abstract: In ontology-based case retrieval system,because the number of cases in the database can double increases with time, the efficiency of case retrieval continues lower. This paper presented a multi dimensional case retrieval algorithm-the DRR(Dimensionality Reduction of R-Tree) , the algorithm dimensionality reduces the case point of the multidimensional space to two-dimensional space point, uses a two-dimensional space points to represent the collection on behalf of the class case points, and biulds R-tree spatial index for this two-dimensional space point accelerates the retrieval efficiency and accuracy by the two search methods. It is proved that the method not only improves the accuracy of case retrieval, but also greatly improves the efficiency of case retrieval.

Key words: Case retrieval, R-tree index, Relative point, Relative vector