High-dimensional crowdsourced data collected from numerous users produces rich knowledge about our society; however, it also brings unprecedented privacy threats to the participants. Local differential privacy (LDP), a variant of differential privacy, is recently proposed as a state-of-the-art privacy notion. Unfortunately, achieving LDP on high-dimensional crowdsourced data publication raises great challenges in terms of both computational efficiency and data utility. To this end, based on the expectation maximization (EM) algorithm and Lasso regression, we first propose efficient multi-dimensional joint distribution estimation algorithms with LDP. Then, we develop a local differentially private high-dimensional data publication algorithm (LoPub) by taking advantage of our distribution estimation techniques. In particular, correlations among multiple attributes are identified to reduce the dimensionality of crowdsourced data, thus speeding up the distribution learning process and achieving high data utility. Extensive experiments on real-world datasets demonstrate that our multivariate distribution estimation scheme significantly outperforms existing estimation schemes in terms of both communication overhead and estimation speed. Moreover, LoPub can keep, on average, 80% and 60% accuracy over the released datasets in terms of support vector machine and random forest classification, respectively.

Significant progress has been made in symbolic music generation with the help of deep learning techniques. However, the tasks covered by symbolic music generation have not been well summarized, and the evolution of generative models for the specific music generation task has not been illustrated systematically. This paper attempts to provide a task-oriented survey of symbolic music generation based on deep learning techniques, covering most of the currently popular music generation tasks. The distinct models under the same task are set forth briefly and strung according to their motivations, basically in chronological order. Moreover, we summarize the common datasets suitable for various tasks, discuss the music representations and the evaluation methods, highlight current challenges in symbolic music generation, and finally point out potential future research directions.

Collecting and analyzing massive data generated from smart devices have become increasingly pervasive in crowdsensing, which are the building blocks for data-driven decision-making. However, extensive statistics and analysis of such data will seriously threaten the privacy of participating users. Local differential privacy (LDP) was proposed as an excellent and prevalent privacy model with distributed architecture, which can provide strong privacy guarantees for each user while collecting and analyzing data. LDP ensures that each user’s data is locally perturbed first in the client-side and then sent to the server-side, thereby protecting data from privacy leaks on both the client-side and server-side. This survey presents a comprehensive and systematic overview of LDP with respect to privacy models, research tasks, enabling mechanisms, and various applications. Specifically, we first provide a theoretical summarization of LDP, including the LDP model, the variants of LDP, and the basic framework of LDP algorithms. Then, we investigate and compare the diverse LDP mechanisms for various data statistics and analysis tasks from the perspectives of frequency estimation, mean estimation, and machine learning. Furthermore, we also summarize practical LDP-based application scenarios. Finally, we outline several future research directions under LDP.

Music emotion recognition, which enables effective and efficient music organization and retrieval, is a challenging subject in the field of music information retrieval. In this paper, we propose a new bidirectional convolutional recurrent sparse network (BCRSN) for music emotion recognition based on convolutional neural networks (CNNs) and recurrent neural networks (RNNs). Our model adaptively learns the sequential-information-included affect-salient features (SII-ASF) from the two-dimensional time-frequency representation (i.e., spectrogram) of music audio signals. By combining feature extraction, affect-salient feature selection, and emotion prediction, the BCRSN can achieve continuous emotion prediction of audio files. To reduce the high computational complexity caused by the numerical-type ground-truth, we propose a weighted hybrid binary representation (WHBR) method that converts the regression prediction process into a weighted combination of multiple binary classification problems. We test our method on two benchmark databases, i.e., the Database for Emotional Analysis in Music (DEAM) and MoodSwings Turk (MTurk). The results show that the WHBR method can greatly reduce the training time and improve the prediction accuracy. The extracted SII-ASF is robust to genre, timbre, and noise variation and is sensitive to emotion. It achieves significant improvement compared to the best performing feature sets in MediaEval 2015. Meanwhile, extensive experiments demonstrate that the proposed method outperforms the state-of-the-art methods.