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BSDAR: Beam Search Decoding with Attention Reward in Neural Keyphrase Generation
Ni'mah, Iftitahu, Menkovski, Vlado, Pechenizkiy, Mykola
This study mainly investigates two decoding problems in neural keyphrase generation: sequence length bias and beam diversity. We introduce an extension of beam search inference based on word-level and n-gram level attention score to adjust and constrain Seq2Seq prediction at test time. Results show that our proposed solution can overcome the algorithm bias to shorter and nearly identical sequences, resulting in a significant improvement of the decoding performance on generating keyphrases that are present and absent in source text.
AdaFair: Cumulative Fairness Adaptive Boosting
Iosifidis, Vasileios, Ntoutsi, Eirini
The widespread use of ML-based decision making in domains with high societal impact such as recidivism, job hiring and loan credit has raised a lot of concerns regarding potential discrimination. In particular, in certain cases it has been observed that ML algorithms can provide different decisions based on sensitive attributes such as gender or race and therefore can lead to discrimination. Although, several fairness-aware ML approaches have been proposed, their focus has been largely on preserving the overall classification accuracy while improving fairness in predictions for both protected and non-protected groups (defined based on the sensitive attribute(s)). The overall accuracy however is not a good indicator of performance in case of class imbalance, as it is biased towards the majority class. As we will see in our experiments, many of the fairness-related datasets suffer from class imbalance and therefore, tackling fairness requires also tackling the imbalance problem. To this end, we propose AdaFair, a fairness-aware classifier based on AdaBoost that further updates the weights of the instances in each boosting round taking into account a cumulative notion of fairness based upon all current ensemble members, while explicitly tackling class-imbalance by optimizing the number of ensemble members for balanced classification error. Our experiments show that our approach can achieve parity in true positive and true negative rates for both protected and non-protected groups, while it significantly outperforms existing fairness-aware methods up to 25% in terms of balanced error.
Measure Contribution of Participants in Federated Learning
Wang, Guan, Dang, Charlie Xiaoqian, Zhou, Ziye
--Federated Machine Learning (FML) creates an ecosystem for multiple parties to collaborate on building models while protecting data privacy for the participants. A measure of the contribution for each party in FML enables fair credits allocation. In this paper we develop simple but powerful techniques to fairly calculate the contributions of multiple parties in FML, in the context of both horizontal FML and vertical FML. For Horizontal FML we use deletion method to calculate the grouped instance influence. For V ertical FML we use Shapley V alues to calculate the grouped feature importance. Our methods open the door for research in model contribution and credit allocation in the context of federated machine learning. I NTRODUCTION Federated Learning or Federated Machine Learning (FML) [1] is introduced to solve privacy issues in machine learning using data from multiple parties.
PixelHop: A Successive Subspace Learning (SSL) Method for Object Classification
A new machine learning methodology, called successive subspace learning (SSL), is introduced in this work. SSL contains four key ingredients: 1) successive near-to-far neighborhood expansion; 2) unsupervised dimension reduction via subspace approximation; 3) supervised dimension reduction via label-assisted regression (LAG); and 4) feature concatenation and decision making. An image-based object classification method, called PixelHop, is proposed to illustrate the SSL design. It is shown by experimental results that the PixelHop method outperforms the classic CNN model of similar model complexity in three benchmarking datasets (MNIST, Fashion MNIST and CIFAR-10). Although SSL and deep learning (DL) have some high-level concept in common, they are fundamentally different in model formulation, the training process and training complexity. Extensive discussion on the comparison of SSL and DL is made to provide further insights into the potential of SSL.
Two Computational Models for Analyzing Political Attention in Social Media
Hemphill, Libby, Schรถpke-Gonzalez, Angela M.
Understanding how political attention is divided and over what subjects is crucial for research on areas such as agenda setting, framing, and political rhetoric. Existing methods for measuring attention, such as manual labeling according to established codebooks, are expensive and can be restrictive. We describe two computational models that automatically distinguish topics in politicians' social media content. Our models---one supervised classifier and one unsupervised topic model---provide different benefits. The supervised classifier reduces the labor required to classify content according to pre-determined topic list. However, tweets do more than communicate policy positions. Our unsupervised model uncovers both political topics and other Twitter uses (e.g., constituent service). These models are effective, inexpensive computational tools for political communication and social media research. We demonstrate their utility and discuss the different analyses they afford by applying both models to the tweets posted by members of the 115th U.S. Congress.
Learning to Generate Questions with Adaptive Copying Neural Networks
Automatic question generation is an important problem in natural language processing. In this paper we propose a novel adaptive copying recurrent neural network model to tackle the problem of question generation from sentences and paragraphs. The proposed model adds a copying mechanism component onto a bidirectional LSTM architecture to generate more suitable questions adaptively from the input data. Our experimental results show the proposed model can outperform the state-of-the-art question generation methods in terms of BLEU and ROUGE evaluation scores.
Transfer Learning with Dynamic Adversarial Adaptation Network
Yu, Chaohui, Wang, Jindong, Chen, Yiqiang, Huang, Meiyu
-- The recent advances in deep transfer learning reveal that adversarial learning can be embedded into deep networks to learn more transferable features to reduce the distribution discrepancy between two domains. Existing adversarial domain adaptation methods either learn a single domain discriminator to align the global source and target distributions, or pay attention to align subdomains based on multiple discriminators. However, in real applications, the marginal (global) and conditional (local) distributions between domains are often contributing differently to the adaptation. There is currently no method to dynamically and quantitatively evaluate the relative importance of these two distributions for adversarial learning. In this paper, we propose a novel Dynamic Adversarial Adaptation Network (DAAN) to dynamically learn domain-invariant representations while quantitatively evaluate the relative importance of global and local domain distributions. T o the best of our knowledge, DAAN is the first attempt to perform dynamic adversarial distribution adaptation for deep adversarial learning. DAAN is extremely easy to implement and train in real applications. We theoretically analyze the effectiveness of DAAN, and it can also be explained in an attention strategy. Extensive experiments demonstrate that DAAN achieves better classification accuracy compared to state-of-the-art deep and adversarial methods. Results also imply the necessity and effectiveness of the dynamic distribution adaptation in adversarial transfer learning.
Decision-Directed Data Decomposition
Davis, Brent D., Jackson, Ethan, Lizotte, Daniel J.
We present an algorithm, Decision-Directed Data Decomposition, which decomposes a dataset into two components. The first contains most of the useful information for a specified supervised learning task, and the second orthogonal component that contains little information about the task. The algorithm is simple and scalable. It can use kernel techniques to help preserve desirable information in the decomposition. We illustrate its application to tasks in two domains, using distributed representations of words and images, and we report state-of-the-art results showcasing $D_4$'s capability to remove information pertaining to gender from word embeddings.
Relaxed Softmax for learning from Positive and Unlabeled data
Tanielian, Ugo, Vasile, Flavian
In recent years, the softmax model and its fast approximations have become the de-facto loss functions for deep neural networks when dealing with multi-class prediction. This loss has been extended to language modeling and recommendation, two fields that fall into the framework of learning from Positive and Unlabeled data. In this paper, we stress the different drawbacks of the current family of softmax losses and sampling schemes when applied in a Positive and Unlabeled learning setup. We propose both a Relaxed Softmax loss (RS) and a new negative sampling scheme based on Boltzmann formulation. We show that the new training objective is better suited for the tasks of density estimation, item similarity and next-event prediction by driving uplifts in performance on textual and recommendation datasets against classical softmax.
Properties of Laplacian Pyramids for Extension and Denoising
This paper analyzes the Laplacian pyramids (LP) algorithm for extending a function sampled on a discrete set of points to outside values. This method was introduced in the context of machine learning by Rabin and Coifman in [20], and is modeled after the classical Laplacian pyramids algorithm of Burt and Adelson [10], which is a standard technique in image processing. The LP extension algorithm has been considered in a variety of applications [14, 11, 24, 1, 18, 12, 2], and several variants have been proposed [15, 21, 22]. The LP algorithm constructs a multiscale decomposition of the estimated function, consisting of averaged differences at successive levels. At each level, the residuals from the previous approximation are averaged and extended to the entire domain.