Questions tagged [latent-semantic-indexing]

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Difference between Latent and Explicit Semantic Analysis

I'm trying to analyse the paper ''Computing Semantic Relatedness using Wikipedia-based Explicit Semantic Analysis''. One component of the system described therein that I'm currently grappling with ...
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296 views

What are some of the advantages and disadvantages of Explicit Semantic Analysis (ESA)?

I am writing a report semantic analysis and I have come across a celebrated paper Computing Semantic Relatedness using Wikipedia-based Explicit Semantic Analysis by Evgeniy Gabrilovich and Shaul ...
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385 views

Supervised semantic analysis

Dimensional reduction and semantic vectorization techniques like LSA, pLSA, LDA and Random Indexing do not take advantage of semantic labeled data like Explicit Semantic Analysis (ESA). I am looking ...
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18 views

Semantic Analysis: Set a default value for examples not in scope of the training set

I am working with a semantic analysis problem and wanted to know if anyone has been able to set a default value, say a probability of zero or 0.5 for phrases/words that the machine learning algorithm ...
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87 views

Latent class in Gaussian mixture model

I would like to get any advice on the latent class in the mixture model. But i wish to do latent code by hand without relying on the existing R package. This is my snippet code to do the finite ...
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308 views

Is Latent Semantic Analysis a clustering algorithm?

The input of LSA is a term frequency matrix of a set of documents. What's the output? If I want to cluster a bunch of news into different clusters, can I use LSA? If not, what's the major uses of LSA? ...
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243 views

Calculating perplexity for LSA

I am new to topic modelling, so kindly bear me if my question is silly. I am trying to calculate perplexity after applying LSA. i am aware that LSA returns negative values, so i followed the steps ...
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309 views

LDA or pLSA for short documents?

I'd like to classify short documents, from a predefined set of words. What algorithm would you suggest, LDA or pLSA ? My use case I have a list of users, and for each user a list of the pages she ...
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149 views

Latent semantic analysis and keyword extraction

Well, I've started with a collection of documents. The aim is to extract keywords for each document. I've made a document-term matrix, to which I applied an singular value decomposition. I've made a ...
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7 views

Transformation of SVD for latent semantic analysis

General Idea: I'm working through a particular implementation of Latent Semantic Analysis via SVD. Here is some example code. fairly simple: ...
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8 views

Topic modelling on only 24 documents gives the same “topic” for any K

Description: I have 24 documents, each one of around 2.5K tokens. They are public speeches. My text preprocessing pipeline is a generic one, including punctuation removal, expansion of English ...
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31 views

Latent Semantic Indexing coordinates vs PCA scores

For PCA: Let $X$ be a mean-centered matrix having as columns observations and as rows features. Via SVD, we have $X = U \Sigma V^\top$. Then PCA scores are $U^\top X = \Sigma V^\top$. For LSA/LSI: ...