112 research outputs found
Semisupervised Autoencoder for Sentiment Analysis
In this paper, we investigate the usage of autoencoders in modeling textual
data. Traditional autoencoders suffer from at least two aspects: scalability
with the high dimensionality of vocabulary size and dealing with
task-irrelevant words. We address this problem by introducing supervision via
the loss function of autoencoders. In particular, we first train a linear
classifier on the labeled data, then define a loss for the autoencoder with the
weights learned from the linear classifier. To reduce the bias brought by one
single classifier, we define a posterior probability distribution on the
weights of the classifier, and derive the marginalized loss of the autoencoder
with Laplace approximation. We show that our choice of loss function can be
rationalized from the perspective of Bregman Divergence, which justifies the
soundness of our model. We evaluate the effectiveness of our model on six
sentiment analysis datasets, and show that our model significantly outperforms
all the competing methods with respect to classification accuracy. We also show
that our model is able to take advantage of unlabeled dataset and get improved
performance. We further show that our model successfully learns highly
discriminative feature maps, which explains its superior performance.Comment: To appear in AAAI 201
Affective Image Content Analysis: Two Decades Review and New Perspectives
Images can convey rich semantics and induce various emotions in viewers.
Recently, with the rapid advancement of emotional intelligence and the
explosive growth of visual data, extensive research efforts have been dedicated
to affective image content analysis (AICA). In this survey, we will
comprehensively review the development of AICA in the recent two decades,
especially focusing on the state-of-the-art methods with respect to three main
challenges -- the affective gap, perception subjectivity, and label noise and
absence. We begin with an introduction to the key emotion representation models
that have been widely employed in AICA and description of available datasets
for performing evaluation with quantitative comparison of label noise and
dataset bias. We then summarize and compare the representative approaches on
(1) emotion feature extraction, including both handcrafted and deep features,
(2) learning methods on dominant emotion recognition, personalized emotion
prediction, emotion distribution learning, and learning from noisy data or few
labels, and (3) AICA based applications. Finally, we discuss some challenges
and promising research directions in the future, such as image content and
context understanding, group emotion clustering, and viewer-image interaction.Comment: Accepted by IEEE TPAM
Two-Stage Fine-Tuning: A Novel Strategy for Learning Class-Imbalanced Data
Classification on long-tailed distributed data is a challenging problem,
which suffers from serious class-imbalance and hence poor performance on tail
classes with only a few samples. Owing to this paucity of samples, learning on
the tail classes is especially challenging for the fine-tuning when
transferring a pretrained model to a downstream task. In this work, we present
a simple modification of standard fine-tuning to cope with these challenges.
Specifically, we propose a two-stage fine-tuning: we first fine-tune the final
layer of the pretrained model with class-balanced reweighting loss, and then we
perform the standard fine-tuning. Our modification has several benefits: (1) it
leverages pretrained representations by only fine-tuning a small portion of the
model parameters while keeping the rest untouched; (2) it allows the model to
learn an initial representation of the specific task; and importantly (3) it
protects the learning of tail classes from being at a disadvantage during the
model updating. We conduct extensive experiments on synthetic datasets of both
two-class and multi-class tasks of text classification as well as a real-world
application to ADME (i.e., absorption, distribution, metabolism, and excretion)
semantic labeling. The experimental results show that the proposed two-stage
fine-tuning outperforms both fine-tuning with conventional loss and fine-tuning
with a reweighting loss on the above datasets.Comment: 20 pages, 6 figure
Data Collection and Quality Challenges in Deep Learning: A Data-Centric AI Perspective
Data-centric AI is at the center of a fundamental shift in software
engineering where machine learning becomes the new software, powered by big
data and computing infrastructure. Here software engineering needs to be
re-thought where data becomes a first-class citizen on par with code. One
striking observation is that a significant portion of the machine learning
process is spent on data preparation. Without good data, even the best machine
learning algorithms cannot perform well. As a result, data-centric AI practices
are now becoming mainstream. Unfortunately, many datasets in the real world are
small, dirty, biased, and even poisoned. In this survey, we study the research
landscape for data collection and data quality primarily for deep learning
applications. Data collection is important because there is lesser need for
feature engineering for recent deep learning approaches, but instead more need
for large amounts of data. For data quality, we study data validation,
cleaning, and integration techniques. Even if the data cannot be fully cleaned,
we can still cope with imperfect data during model training using robust model
training techniques. In addition, while bias and fairness have been less
studied in traditional data management research, these issues become essential
topics in modern machine learning applications. We thus study fairness measures
and unfairness mitigation techniques that can be applied before, during, or
after model training. We believe that the data management community is well
poised to solve these problems
Hierarchical Interaction Networks with Rethinking Mechanism for Document-level Sentiment Analysis
Document-level Sentiment Analysis (DSA) is more challenging due to vague
semantic links and complicate sentiment information. Recent works have been
devoted to leveraging text summarization and have achieved promising results.
However, these summarization-based methods did not take full advantage of the
summary including ignoring the inherent interactions between the summary and
document. As a result, they limited the representation to express major points
in the document, which is highly indicative of the key sentiment. In this
paper, we study how to effectively generate a discriminative representation
with explicit subject patterns and sentiment contexts for DSA. A Hierarchical
Interaction Networks (HIN) is proposed to explore bidirectional interactions
between the summary and document at multiple granularities and learn
subject-oriented document representations for sentiment classification.
Furthermore, we design a Sentiment-based Rethinking mechanism (SR) by refining
the HIN with sentiment label information to learn a more sentiment-aware
document representation. We extensively evaluate our proposed models on three
public datasets. The experimental results consistently demonstrate the
effectiveness of our proposed models and show that HIN-SR outperforms various
state-of-the-art methods.Comment: 17 pages, accepted by ECML-PKDD 202
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