LSI就是这样一种维数约减方法。它可以通过对“文档向量矩阵”进行解奇异值分解（SVD: Singular Value Decomposition）运算，自动计算得到一个比原始空间小得多的有效语义空间-LSI is such a dimensionality reduction method. It can be through the "document vector matrix" for the singular value decomposition (SVD: Singular Valu