Latent Dirichlet allocation

About: Latent Dirichlet allocation is a research topic. Over the lifetime, 5351 publications have been published within this topic receiving 212555 citations. The topic is also known as: LDA.

Efficient Methods for Incorporating Knowledge into Topic Models

Abstract: Latent Dirichlet allocation (LDA) is a popular topic modeling technique for exploring hidden topics in text corpora. Increasingly, topic modeling needs to scale to larger topic spaces and use richer forms of prior knowledge, such as word correlations or document labels. However, inference is cumbersome for LDA models with prior knowledge. As a result, LDA models that use prior knowledge only work in small-scale scenarios. In this work, we propose a factor graph framework, Sparse Constrained LDA (SC-LDA), for efficiently incorporating prior knowledge into LDA. We evaluate SC-LDA’s ability to incorporate word correlation knowledge and document label knowledge on three benchmark datasets. Compared to several baseline methods, SC-LDA achieves comparable performance but is significantly faster.

NUS-ML:Improving Word Sense Disambiguation Using Topic Features

Abstract: We participated in SemEval-1 English coarse-grained all-words task (task 7), English fine-grained all-words task (task 17, subtask 3) and English coarse-grained lexical sample task (task 17, subtask 1). The same method with different labeled data is used for the tasks; SemCor is the labeled corpus used to train our system for the all-words tasks while the labeled corpus that is provided is used for the lexical sample task. The knowledge sources include part-of-speech of neighboring words, single words in the surrounding context, local collocations, and syntactic patterns. In addition, we constructed a topic feature, targeted to capture the global context information, using the latent dirichlet allocation (LDA) algorithm with unlabeled corpus. A modified naive Bayes classifier is constructed to incorporate all the features. We achieved 81.6%, 57.6%, 88.7% for coarse-grained all-words task, fine-grained all-words task and coarse-grained lexical sample task respectively.

Annotating images and image objects using a hierarchical dirichlet process model

Abstract: Many applications call for learning to label individual objects in an image where the only information available to the learner is a dataset of images with their associated captions, i.e., words that describe the image content without specifically labeling the individual objects. We address this problem using a multi-modal hierarchical Dirichlet process model (MoM-HDP) - a nonparametric Bayesian model which provides a generalization for multi-model latent Dirichlet allocation model (MoM-LDA) used for similar problems in the past. We apply this model for predicting labels of objects in images containing multiple objects. During training, the model has access to an un-segmented image and its caption, but not the labels for each object in the image. The trained model is used to predict the label for each region of interest in a segmented image. MoM-HDP generalizes a multi-modal latent Dirichlet allocation model in that it allows the number of components of the mixture model to adapt to the data. The model parameters are efficiently estimated using variational inference. Our experiments show that MoM-HDP performs just as well as or better than the MoM-LDA model (regardless the choice of the number of clusters in the MoM-LDA model).

A Text-Based Analysis of Corporate Innovation

Abstract: We develop a new measure of innovation using the text of analyst reports of S&P 500 firms. Our text-based measure gives a useful description of innovation by firms with and without patenting and R&...

An unsupervised topic-sentiment joint probabilistic model for detecting deceptive reviews

Abstract: In electronic commerce, online reviews play very important roles in customers’ purchasing decisions. Unfortunately, malicious sellers often hire buyers to fabricate fake reviews to improve their reputation. In order to detect deceptive reviews and mine the topics and sentiments from the reviews, in this paper, we propose an unsupervised topic-sentiment joint probabilistic model (UTSJ) based on Latent Dirichlet Allocation (LDA) model. This model first employs Gibbs sampling algorithm to approximate parameters of maximum likelihood function offline and obtain topic-sentiment joint probabilistic distribution vector for each review. Secondly, a Random Forest classifier and a SVM (Support Vector Machine) classifier are trained offline, respectively. Experimental results on real-life datasets show that our proposed model is better than baseline models such as n-grams, character n-grams in token, POS (part-of-speech), LDA, and JST (Joint Sentiment/Topic). Moreover, our UTSJ model outperforms or performs similarly to benchmark models in detecting deceptive reviews over balanced dataset and unbalanced dataset in different domains. Particularly, our UTSJ model is good at dealing with real-life unbalanced big data, which makes it very suitable for being applied in e-commerce environment.