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LSA is relatively similar in some abstract sense to the published pagerank algorithm. LDA is more powerful, in the sense that it can account for more complex re
by cdavid 16y ago
LSA is relatively similar in some abstract sense to the published pagerank algorithm. LDA is more powerful, in the sense that it can account for more complex relationships (but may be less accurate with large number of data - I have really no idea how those would scale and compare at google-like size).
- nl 16y agoCan you explain this some more? My understanding of LDA is that it gives you document scores against queries based on the topics extracted using the LDA algorithm on the text in the page. Pagerank, on the other hand scores based on external pointers (ie, references) but doesn't have anything to do with the text on the page.
- noelwelsh 16y agoIt's the abstract sense that is important. Pagerank is a dimensionality reduction technique. It finds the first eigenvector of the transition matrix. Eigenvectors = PCA. LSI is basically PCA, but applied to the document-term matrix. LDA is a dimensionality reduction technique that makes use of more information.
- nl 16y agoOh, I see. I thought you were talking about some functional similarities, not the mathematical similarities.