LSA figure

A cool figure easily describing SVD process for LSA.

LSA cannot address the polysem problem, but the synonym problem can be addressed by this model

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LSI, LSA, pLSA, LDA, etc

•What is the difference between LSI and LSA?

–LSI refers to using this technique for indexing, or information retrieval.

–LSA refers to using it for everything else.

–It’s the same technique, just different applications.

 

•Two problems that arise using the vector space model:

–synonymy: many ways to refer to the same object, e.g. car and automobile

•leads to poor recall

–polysemy: most words have more than one distinct meaning, e.g. model, python, chip

•leads to poor precision