Results 1 - 10
of
999
Reading Tea Leaves: How Humans Interpret Topic Models
"... Probabilistic topic models are a popular tool for the unsupervised analysis of text, providing both a predictive model of future text and a latent topic representation of the corpus. Practitioners typically assume that the latent space is semantically meaningful. It is used to check models, summariz ..."
Abstract
-
Cited by 229 (24 self)
- Add to MetaCart
(Show Context)
Probabilistic topic models are a popular tool for the unsupervised analysis of text, providing both a predictive model of future text and a latent topic representation of the corpus. Practitioners typically assume that the latent space is semantically meaningful. It is used to check models, summarize the corpus, and guide exploration of its contents. However, whether the latent space is interpretable is in need of quantitative evaluation. In this paper, we present new quantitative methods for measuring semantic meaning in inferred topics. We back these measures with large-scale user studies, showing that they capture aspects of the model that are undetected by previous measures of model quality based on held-out likelihood. Surprisingly, topic models which perform better on held-out likelihood may infer less semantically meaningful topics. 1
Twitter as a corpus for sentiment analysis and opinion mining
- In Proceedings of the Seventh Conference on International Language Resources and Evaluation
"... Microblogging today has become a very popular communication tool among Internet users. Millions of users share opinions on different aspects of life everyday. Therefore microblogging web-sites are rich sources of data for opinion mining and sentiment analysis. Because microblogging has appeared rela ..."
Abstract
-
Cited by 217 (2 self)
- Add to MetaCart
(Show Context)
Microblogging today has become a very popular communication tool among Internet users. Millions of users share opinions on different aspects of life everyday. Therefore microblogging web-sites are rich sources of data for opinion mining and sentiment analysis. Because microblogging has appeared relatively recently, there are a few research works that were devoted to this topic. In our paper, we focus on using Twitter, the most popular microblogging platform, for the task of sentiment analysis. We show how to automatically collect a corpus for sentiment analysis and opinion mining purposes. We perform linguistic analysis of the collected corpus and explain discovered phenomena. Using the corpus, we build a sentiment classifier, that is able to determine positive, negative and neutral sentiments for a document. Experimental evaluations show that our proposed techniques are efficient and performs better than previously proposed methods. In our research, we worked with English, however, the proposed technique can be used with any other language. 1.
Improvements In Part-of-Speech Tagging With an Application To German
- In Proceedings of the ACL SIGDAT-Workshop
, 1995
"... This paper presents a couple of extensions to a basic Markov Model tagger (called TreeTagger) which improve its accuracy when trained on small corpora. The basic tagger was originally developed for English [Schmid, 1994]. The extensions together reduced error rates on a German test corpus by more th ..."
Abstract
-
Cited by 201 (1 self)
- Add to MetaCart
This paper presents a couple of extensions to a basic Markov Model tagger (called TreeTagger) which improve its accuracy when trained on small corpora. The basic tagger was originally developed for English [Schmid, 1994]. The extensions together reduced error rates on a German test corpus by more than a third.
Learning concept hierarchies from text corpora using formal concept analysis
- J. Artif. Intell. Res
, 2005
"... We present a novel approach to the automatic acquisition of taxonomies or concept hierarchies from a text corpus. The approach is based on Formal Concept Analysis (FCA), a method mainly used for the analysis of data, i.e. for investigating and processing explicitly given information. We follow Harri ..."
Abstract
-
Cited by 158 (5 self)
- Add to MetaCart
(Show Context)
We present a novel approach to the automatic acquisition of taxonomies or concept hierarchies from a text corpus. The approach is based on Formal Concept Analysis (FCA), a method mainly used for the analysis of data, i.e. for investigating and processing explicitly given information. We follow Harris ’ distributional hypothesis and model the context of a certain term as a vector representing syntactic dependencies which are automatically acquired from the text corpus with a linguistic parser. On the basis of this context information, FCA produces a lattice that we convert into a special kind of partial order constituting a concept hierarchy. The approach is evaluated by comparing the resulting concept hierarchies with hand-crafted taxonomies for two domains: tourism and finance. We also directly compare our approach with hierarchical agglomerative clustering as well as with Bi-Section-KMeans as an instance of a divisive clustering algorithm. Furthermore, we investigate the impact of using different measures weighting the contribution of each attribute as well as of applying a particular smoothing technique to cope with data sparseness. 1.
An end-to-end discriminative approach to machine translation
- In Proceedings of the Joint International Conference on Computational Linguistics and Association of Computational Linguistics (COLING/ACL
, 2006
"... We present a perceptron-style discriminative approach to machine translation in which large feature sets can be exploited. Unlike discriminative reranking approaches, our system can take advantage of learned features in all stages of decoding. We first discuss several challenges to error-driven disc ..."
Abstract
-
Cited by 156 (3 self)
- Add to MetaCart
(Show Context)
We present a perceptron-style discriminative approach to machine translation in which large feature sets can be exploited. Unlike discriminative reranking approaches, our system can take advantage of learned features in all stages of decoding. We first discuss several challenges to error-driven discriminative approaches. In particular, we explore different ways of updating parameters given a training example. We find that making frequent but smaller updates is preferable to making fewer but larger updates. Then, we discuss an array of features and show both how they quantitatively increase BLEU score and how they qualitatively interact on specific examples. One particular feature we investigate is a novel way to introduce learning into the initial phrase extraction process, which has previously been entirely heuristic. 1
Learning Bilingual Lexicons from Monolingual Corpora
"... We present a method for learning bilingual translation lexicons from monolingual corpora. Word types in each language are characterized by purely monolingual features, such as context counts and orthographic substrings. Translations are induced using a generative model based on canonical correlation ..."
Abstract
-
Cited by 115 (1 self)
- Add to MetaCart
(Show Context)
We present a method for learning bilingual translation lexicons from monolingual corpora. Word types in each language are characterized by purely monolingual features, such as context counts and orthographic substrings. Translations are induced using a generative model based on canonical correlation analysis, which explains the monolingual lexicons in terms of latent matchings. We show that high-precision lexicons can be learned in a variety of language pairs and from a range of corpus types. 1
Learning Taxonomic Relations from Heterogeneous Evidence
"... We present a novel approach to the automatic acquisition of taxonomic relations. The main difference to earlier approaches is that we do not only consider one single source of evidence, i.e. a specific algorithm or approach, but examine the possibility of learning taxonomic relations by considerin ..."
Abstract
-
Cited by 111 (9 self)
- Add to MetaCart
(Show Context)
We present a novel approach to the automatic acquisition of taxonomic relations. The main difference to earlier approaches is that we do not only consider one single source of evidence, i.e. a specific algorithm or approach, but examine the possibility of learning taxonomic relations by considering various and heterogeneous forms of evidence. In particular, we derive these different evidences by using well-known NLP techniques and resources and combine them via two simple strategies. Our approach shows very promising results compared to other results from the literature. The main aim of the work presented in this paper is (i) to gain insight into the behaviour of different approaches to learn taxonomic relations, (ii) to provide a first step towards combining these different approaches, and (iii) to establish a baseline for further research.
From Temporal Expressions to Temporal Information: Semantic Tagging of News Messages
- in Proceedings of the ACL-2001 Workshop on Temporal and Spatial Information Processing, ACL-2001. Toulose
, 2001
"... We present a semantic tagging system for temporal expressions and discuss how the temporal information conveyed by these expressions can be extracted. The performance of the system was evaluated wrt. a small hand-annotated corpus of news messages. 1 ..."
Abstract
-
Cited by 74 (0 self)
- Add to MetaCart
(Show Context)
We present a semantic tagging system for temporal expressions and discuss how the temporal information conveyed by these expressions can be extracted. The performance of the system was evaluated wrt. a small hand-annotated corpus of news messages. 1
Extracting Semantic Orientations of Words using Spin Model
- In ACL
, 2005
"... We propose a method for extracting semantic orientations of words: desirable or undesirable. Regarding semantic orientations as spins of electrons, we use the mean field approximation to compute the approximate probability function of the system instead of the intractable actual probability function ..."
Abstract
-
Cited by 67 (1 self)
- Add to MetaCart
(Show Context)
We propose a method for extracting semantic orientations of words: desirable or undesirable. Regarding semantic orientations as spins of electrons, we use the mean field approximation to compute the approximate probability function of the system instead of the intractable actual probability function. We also propose a criterion for parameter selection on the basis of magnetization. Given only a small number of seed words, the proposed method extracts semantic orientations with high accuracy in the experiments on English lexicon. The result is comparable to the best value ever reported. 1
Shallow Morphological Analysis in Monolingual Information Retrieval for Dutch, German and Italian
- Evaluation of Cross-Language Information Retrieval Systems, CLEF 2001, volume 2406 of Lecture Notes in Computer Science
, 2001
"... This paper describes the experiments of our team for CLEF 2001, which includes both official and post-submission runs. We took part in the monolingual task, for Dutch, German, and Italian. The focus of our experiments was on the effects of morphological analyses such as stemming and compound spli ..."
Abstract
-
Cited by 51 (13 self)
- Add to MetaCart
This paper describes the experiments of our team for CLEF 2001, which includes both official and post-submission runs. We took part in the monolingual task, for Dutch, German, and Italian. The focus of our experiments was on the effects of morphological analyses such as stemming and compound splitting on retrieval effectiveness. Confirming earlier reports on retrieval in compound splitting languages such as Dutch and German, we found improvements to be around 25% for German and as much as 69% for Dutch. For Italian, lexiconbased stemming resulted in gains of up to 25%. 1
