The decision tree algorithm is an effective machine learning technique, but it cannot uncover causal relationships within data. To overcome this limitation, the causal decision tree was proposed, which combines causal discovery with decision tree principles. This method is particularly effective at identifying causal relationships in complex datasets. Currently, causal decision tree algorithms are being applied in various fields, including biology and politics. However, existing causal decision tree algorithms do not account the fairness. To fill this gap, this paper proposes the Fair Causal Decision Tree (FCDT), constructed through a fair post-pruning process. The FCDT ensures the algorithm's fairness while maintaining the causality inherent in the causal decision tree. To preserve the algorithm's causality, this paper introduces the Causal Structure Change Constraint (CSCC), which guarantees that the causal decision tree retains its strong causal properties when handling unfair nodes. This innovative constraint ensures that any structural modifications during the fairness adjust-ment process almost not decrease the algorithm's causality. The experiments were conducted on multiple datasets, and the results demonstrate that the proposed algorithm enhances fairness by approximately 10% compared to traditional causal decision tree algorithms, with only about a 1 % decrease in recall rate.

This paper extends the Fuzzy c-means (FCM) algorithm and proposes the Ordered pair of normalized real numbers clustering (OPNC) algorithm. The OPNC algorithm adopts the paradigm of learning in parallel universes and simultaneously uses multiple similarity measures to convert ordinary data into ordered pairs of normalized real numbers (OPNs). Clustering is performed with OPNs, and OPNs contain different similarity information, so the OPNC algorithm can further improve the clustering performance by combining different similarity measures. Experiments on multiple real datasets and comparisons with other clustering algorithms verified that the OPNC algorithm has excellent performance.

Gradient boosting is an efficient and scalable supervised machine learning technique, and most scaling models based on gradient boosting perform well on point regression tasks, but they can only be run in batch settings and cannot be learned online on the data stream. To solve this problem, this paper proposes a tree regression method based on incremental gradient boosting (IGB). The proposed method uses gradient information as a splitting metric and applies the Hoeffding inequality incrementally to construct decision trees to achieve incremental gradient improvement. After a large number of experimental evaluations, the proposed method outperforms the existing online regression trees in point regression tasks, and in some cases, has comparable performance to the batch gradient boosting tree model.

Learned indexes incorporate machine learning models to predict the locations of keys in the dataset. However, achieving accurate prediction is difficult due to the learning models’ inability to fully capture data distribution. Existing learned indexes used data partition or pre-set error bounds to solve this problem. However, data partition requires constructing a higher index structure, and pre-set error bounds have to train many learning models. In the paper, we propose a new Hierarchical Learned Index with High-Precision query on end nodes (HLIHP), which aims to achieve higher query precision with lower training cost. First, we propose a Precision Correction Model to correct the prediction results, which associates the predicted results with the real positions of the keys. Then, a lightweight learned model is used to construct the superstructure of the index, which can find the end nodes quickly with low training cost and effectively support the query operation. We conduct experiments on four datasets, including covid, genome, osm, and planet, to evaluate the performance of our proposal. The results show that compared to the five hierarchical learned indexes, RMI, PGM-index, XIndex, FINEdex, and ALEX, HLIHP shows on average 2.42×, 1.78×, 5.68×, 6.11×, and 1.48× higher throughput in lookup performance.

The fairness and bias of spectral clustering algorithms have attracted considerable research interest in recent years. Currently fair spectral clustering algorithms are based on the notions of group fairness and individual fairness, which effectively reduce decision bias for similar individuals and sensitive groups. Existing fair spectral clustering algorithms achieve a certain degree of resource redistribution during the clustering process for a particular individual or part of a group, but there is still a situation where the final decision is unfair to the oversized or undersized result clusters. To this end, we present the first principled study of Scale Fairness on Spectral Clustering and propose the SFSC algorithm, which aims to effectively reduce the possibility of the results being oversized or undersized clusters by introducing entropy computation into the spectral clustering process. We measure the scale fairness of clusters by two statistical metrics, and demonstrate on eight classical and real-world datasets that SFSC has better fairness performance compared to spectral clustering while having comparable clustering effect. To the best of our knowledge, this paper is the first study to propose scale fairness for spectral clustering.

The graph mining algorithm has been widely used in various fields in recent years, among which the spectral clustering algorithm is based on spectral graph theory, which has the ability to cluster on an arbitrarily shaped sample space and converge to the global optimal solution compared with the traditional clustering algorithm. As algorithmic fairness has become a research hot-spot recently, more and more fairness constraints have been introduced into spectral clustering. Most studies focus on group fairness, with only a small number providing individual-level fairness constraints. Existing fair spectral clustering algorithms focus only on whether the clustering results are fair or the decreased rate of fairness loss. To this end, we propose an Individual Fair Spectral Clustering with Cost constraints (IFSCC), which ensures the clustering effect while also improving a certain degree of individual fairness. The experimental results show that IFSCC has the lowest COST value while having a comparable clustering effect compared to other individual fair spectral clustering algorithms. To the best of our knowledge, this paper is the first study to make a trade-off between the clustering effect and fairness performance.

Fuzzy C-Means (FCM) clustering is a classic clustering algorithm, which is widely used in the real world. Despite the distinct advantages of FCM algorithm, whether the usage of fairness constraint in the FCM could improve clustering fairness remains fully elusive. By introducing a novel fair loss term into the objective function, a Fair Fuzzy C-Means (FFCM) algorithm was proposed in this current study. We proved that the membership value was constrained by distance and fairness in the meantime during the optimization process in the proposed objective function. By studying the Fuzzy C-Means Clustering with fairness constraint problem and proposing a fair fuzzy C-means method, this study provided mechanism understanding in achieving the fairness constraint in Fuzzy C-Means clustering and bridged up the gap of fair fuzzy clustering.

In this paper, we demonstrate Post2Story, which aims to detect events and generate storylines on microblog posts. Post2Story has several new features: (1) It proposes to employ social influence to extract events from microblogs. (2) It presents a new Event Graph Convolutional Network (E-GCN) model to learn the latent relationships among events, which can help predict the story branch of an event and link events. (3) It offers a user-friendly interface to extract and visualize the development of events. After an introduction to the system architecture and key technologies of Post2Story, we demonstrate the functionalities of Post2Story on a real dataset.

This paper demonstrates a prototype system called Post2Event that aims to extract key events from microblogs.While many events are hidden in microblogs, people may only care about those critical events, which are named key events in Post2Event.Specially, we propose to model the topic-related significance of an event and integrate the influence with the temporal characteristics of the event to measure the event's importance.We briefly present the architecture and technical details of Post2Event.Then, we report the comparative results of Post2Event on a real dataset.Finally, we demonstrate the running process of the system.

Spectral clustering is a popular clustering method because it gives a natural way to reduce the dimensionality of data using eigenvectors. It is well known that the performance of spectral clustering could be improved via regularization. Nevertheless, it is hard to cope with the different cases by only one constant regularization parameter. To solve such a problem, a novel regularized spectral clustering method is proposed. Specifically, two modules are integrated in the proposed method. First, under matrix perturbation analysis, we prove that the entropy can be used as a rank score function to reveal the informative eigenvector, and the eigenvector corresponding to the minimal entropy will be the regularization to regularize the data matrix instead of a constant regularization parameter. Second, in order to ensure the perturbation on eigenspace is within the effective range, a perturbation boundary on eigenvectors is given. Numerical results showed that our proposal has superior performance than spectral clustering and k-means algorithm.

There are a great number of complex relations among different characters in an opera. Retrieving such relations is crucial for performers and audience to accurately understand the features and behaviour of roles. Aiming to automatically extract relations among characters in an opera, in this paper we propose an effective method that can extract character relations from opera scripts. Firstly, we construct a uniform reasoning framework for opera scripts. Based on this model, we propose a deep syntax-parsing method to detect character relations from opera scripts. After that, we propose a new deep learning approach called SL-Bi-LSTM-CRF to extract the objects involved in character relations. The proposed SL-Bi-LSTM-CRF algorithm is a sentence-level relation extraction algorithm based on the Bi-directional LSTM with a CRF layer. With this mechanism, we are able to get a detailed description for character relations. We conduct experiments on a real dataset of opera scripts. The experimental results in terms of precision, recall, and F-score suggest the effectiveness of our proposal.