In real-world applications, data-driven classifiers often grapple with a three-pronged challenge: data arrives in a continuous stream, most data in the wild are often unlabeled, and there is a critical need to maintain fairness in predictions across different sub-groups. Existing methods falter when addressing all these three factors concurrently. This work tackles this challenge by addressing a novel paradigm: Fairness-Aware Active Online Learning. We introduce a simple yet effective approach - FACTION, which actively selects the most crucial data points for labeling, going beyond traditional methods by considering both model uncertainty (epistemic uncertainty) and a newly introduced fairness notion derived from this very uncertainty. Additionally, FACTION leverages a system adept at identifying out-of-distribution samples within online learning environ-ments. Extensive evaluations on real-world datasets, coupled with theoretical analysis, demonstrate FACTION's effectiveness in handling this complex challenge. Our model demonstrably outperforms relevant baselines adapted for this new setting.

The ConfliLPC framework introduces an innovative integration of Logits and Parameter Calibration (LPC) with the ConfliBERT model, tailored specifically for the nuanced analysis of political conflict and violence. This paper details the development and application of ConfliLPC, highlighting its robust capability to adapt to evolving data landscapes without succumbing to catastrophic forgetting (CF), a common challenge in machine learning models applied to dynamic domains such as political science. ConfliLPC enhances accuracy and adaptability by continually adjusting its parameters to accommodate new information while retaining valuable historical insights. The framework has been rigorously tested across various conflict scenarios, demonstrating superior performance in real-time analysis and predictive tasks. This work serves as a significant contribution to the fields of political science, conflict research, and applied machine learning, providing a powerful tool for analysts and policymakers engaged in the understanding and resolution of political conflict. The experimental results highlight the efficiency of the ConfliLPC method and its capability to minimize CF. Our code is publicly available1

Traditional machine learning relies on centralized data, which poses risks to privacy and strains networks when collecting data from multiple centers. Federated Learning, introduced to address these challenges, trains models on various clients, transfers them to a central server to aggregate their knowledge in a global model, and shares the global model with clients to transfer knowledge among them. In real-world problems, data are not distributed independently and identically among different data sources. The non-IID nature of data makes the learning process more challenging, especially when the problem is non-convex. In such cases, the global model may become trapped in local optima. In this paper, we have introduced an approach that employs techniques from metaheuristic optimization algorithms to help the learning process escape from local optima. Relying on the concepts of exploration and exploitation, the optimization process is directed toward promising areas. Experiments conducted on several non-IID datasets show that our algorithm outperforms others in a wide variety of cases.

The endeavor to preserve the generalization of a fair and invariant classifier across domains, especially in the presence of distribution shifts, becomes a significant and intricate challenge in machine learning. In response to this challenge, numerous effective algorithms have been developed with a focus on addressing the problem of fairness-aware domain generalization. These algorithms are designed to navigate various types of distribution shifts, with a particular emphasis on covariate and dependence shifts. In this context, covariate shift pertains to changes in the marginal distribution of input features, while dependence shift involves alterations in the joint distribution of the label variable and sensitive attributes. In this paper, we introduce a simple but effective approach that aims to learn a fair and invariant classifier by simultaneously addressing both covariate and dependence shifts across domains. We assert the existence of an underlying transformation model can transform data from one domain to another, while preserving the semantics related to non-sensitive attributes and classes. By augmenting various synthetic data domains through the model, we learn a fair and invariant classifier in source domains. This classifier can then be generalized to unknown target domains, maintaining both model prediction and fairness concerns. Extensive empirical studies on four benchmark datasets demonstrate that our approach surpasses state-of-the-art methods.

The fairness-aware online learning framework has emerged as a potent tool within the context of continuous lifelong learning. In this scenario, the learner’s objective is to progressively acquire new tasks as they arrive over time, while also guaranteeing statistical parity among various protected sub-populations, such as race and gender when it comes to the newly introduced tasks. A significant limitation of current approaches lies in their heavy reliance on the i.i.d (independent and identically distributed) assumption concerning data, leading to a static regret analysis of the framework. Nevertheless, it’s crucial to note that achieving low static regret does not necessarily translate to strong performance in dynamic environments characterized by tasks sampled from diverse distributions. In this article, to tackle the fairness-aware online learning challenge in evolving settings, we introduce a unique regret measure, FairSAR, by incorporating long-term fairness constraints into a strongly adapted loss regret framework. Moreover, to determine an optimal model parameter at each time step, we introduce an innovative adaptive fairness-aware online meta-learning algorithm, referred to as FairSAOML. This algorithm possesses the ability to adjust to dynamic environments by effectively managing bias control and model accuracy. The problem is framed as a bi-level convex-concave optimization, considering both the model’s primal and dual parameters, which pertain to its accuracy and fairness attributes, respectively. Theoretical analysis yields sub-linear upper bounds for both loss regret and the cumulative violation of fairness constraints. Our experimental evaluation of various real-world datasets in dynamic environments demonstrates that our proposed FairSAOML algorithm consistently outperforms alternative approaches rooted in the most advanced prior online learning methods.

In the problem of online learning for changing environments, data are sequentially received one after another over time, and their distribution assumptions may vary frequently. Although existing methods demonstrate the effectiveness of their learning algorithms by providing a tight bound on either dynamic regret or adaptive regret, most of them completely ignore learning with model fairness, defined as the statistical parity across different sub-population (e.g., race and gender). Another drawback is that when adapting to a new environment, an online learner needs to update model parameters with a global change, which is costly and inefficient. Inspired by the sparse mechanism shift hypothesis [22], we claim that changing environments in online learning can be attributed to partial changes in learned parameters that are specific to environments and the rest remain invariant to changing environments. To this end, in this paper, we propose a novel algorithm under the assumption that data collected at each time can be disentangled with two representations, an environment-invariant semantic factor and an environment-specific variation factor. The semantic factor is further used for fair prediction under a group fairness constraint. To evaluate the sequence of model parameters generated by the learner, a novel regret is proposed in which it takes a mixed form of dynamic and static regret metrics followed by a fairness-aware long-term constraint. The detailed analysis provides theoretical guarantees for loss regret and violation of cumulative fairness constraints. Empirical evaluations on real-world datasets demonstrate our proposed method sequentially outperforms baseline methods in model accuracy and fairness.

Recent advances in natural language processing (NLP) and Big Data technologies have been crucial for scientists to analyze political unrest and violence, prevent harm, and promote global conflict management. Government agencies and public security organizations have invested heavily in deep learning-based applications to study global conflicts and political violence. However, such applications involving text classification, information extraction, and other NLP-related tasks require extensive human efforts in annotating/labeling texts. While limited labeled data may drastically hurt the models’ performance (over-fitting), large demands on annotation tasks may turn real-world applications impracticable. To address this problem, we propose Confli-T5, a prompt-based method that leverages the domain knowledge from existing political science ontology to generate synthetic but realistic labeled text samples in the conflict and mediation domain. Our model allows generating textual data from the ground up and employs our novel Double Random Sampling mechanism to improve the quality (coherency and consistency) of the generated samples. We conduct experiments over six standard datasets relevant to political science studies to show the superiority of Confli-T5. Our codes are publicly available1.

The fairness-aware online learning framework has arisen as a powerful tool for the continual lifelong learning setting. The goal for the learner is to sequentially learn new tasks where they come one after another over time and the learner ensures the statistic parity of the new coming task across different protected sub-populations (e.g. race and gender). A major drawback of existing methods is that they make heavy use of the i.i.d assumption for data and hence provide static regret analysis for the framework. However, low static regret cannot imply a good performance in changing environments where tasks are sampled from heterogeneous distributions. To address the fairness-aware online learning problem in changing environments, in this paper, we first construct a novel regret metric FairSAR by adding long-term fairness constraints onto a strongly adapted loss regret. Furthermore, to determine a good model parameter at each round, we propose a novel adaptive fairness-aware online meta-learning algorithm, namely FairSAOML, which is able to adapt to changing environments in both bias control and model precision. The problem is formulated in the form of a bi-level convex-concave optimization with respect to the model's primal and dual parameters that are associated with the model's accuracy and fairness, respectively. The theoretic analysis provides sub-linear upper bounds for both loss regret and violation of cumulative fairness constraints. Our experimental evaluation on different real-world datasets with settings of changing environments suggests that the proposed FairSAOML significantly outperforms alternatives based on the best prior online learning approaches.

In this paper, we address challenges of detecting instances from emerging classes over a non-stationary data stream during data classification. In particular, data instances from an entirely unknown class may appear in a data stream over time. Existing classification techniques utilize unsupervised clustering to identify emergence of such data instances. Unfortunately, they make strong assumptions which are typically invalid in practice; (i) Most instances associated with a class are closer to each other in feature space than instances associated with different classes, (ii) Covariates of data are normalized through an oracle to overcome the effect of a few data instances having large feature values, and (iii) Labels of instances from emerging classes are readily available soon after detection. To address the challenges that occur in practice when the above assumptions are weak, i.e., instances of each class are scattered and the true labels of novel class instances are sparsely available, we propose a practical semi-supervised emerging class detection framework. Particularly, we aim to identify similar data instances within local regions in feature space by incorporating a mutual graph clustering mechanism. We also perform online normalization along the data stream instead of assuming an oracle, and propose a classification technique that uses only a small amount of true labels for training and emerging class detection. Our empirical evaluation of this framework on real-world datasets demonstrates its superiority of classification performance compared to existing methods, while using significantly fewer labeled instances.

Knowledge discovery and extraction approaches attract special attention across industries and areas moving toward the 5V Era. In the political and social sciences, scholars and governments dedicate considerable resources to develop intelligent systems for monitoring, analyzing and predicting conflicts and affairs involving political entities across the globe. Such systems rely on background knowledge from external knowledge bases, that conflict experts commonly maintain manually. The high costs and extensive human efforts associated with updating and extending these repositories often compromise their correctness of. Here we introduce CoMe-KE (Conflict and Mediation Knowledge Extractor) to extend automatically knowledge bases about conflict and mediation events. We explore state-of-the-art natural language models to discover new political entities, their roles and status from news. We propose a distant supervised method and propose an innovative zero-shot approach based on a dynamic hypothesis procedure. Our methods leverage pre-trained models through transfer learning techniques to obtain excellent results with no need for a labeled data. Finally, we demonstrate the superiority of our method through a comprehensive set of experiments involving two study cases in the social sciences domain. CoMe-KE significantly outperforms the existing baseline, with (on average) double of the performance retrieving new political entities.

Political scientists and security agencies increasingly rely on computerized event data generation to track conflict processes and violence around the world. However, most of these approaches rely on pattern-matching techniques constrained by large dictionaries that are too costly to develop, update, or expand to emerging domains or additional languages. In this paper, we provide an effective solution to those challenges. Here we develop the 3M-Transformers (Multilingual, Multi-label, Multitask) approach for Event Coding from domain specific multilingual corpora, dispensing external large repositories for such task, and expanding the substantive focus of analysis to organized crime, an emerging concern for security research. Our results indicate that our 3M-Transformers configurations outperform state-of-the-art usual Transformers models (BERT and XLM-RoBERTa) for coding events on actors, actions and locations in English, Spanish, and Portuguese languages.

Deep neural networks have significantly contributed to the success in predictive accuracy for classification tasks. However, they tend to make over-confident predictions in real-world settings, where domain shifting and out-of-distribution (OOD) examples exist. Most research on uncertainty estimation focuses on computer vision because it provides visual validation on uncertainty quality. However, few have been presented in the natural language process domain. Unlike Bayesian methods that indirectly infer uncertainty through weight uncertainties, current evidential uncertainty-based methods explicitly model the uncertainty of class probabilities through subjective opinions. They further consider inherent uncertainty in data with different root causes, vacuity (i.e., uncertainty due to a lack of evidence) and dissonance (i.e., uncertainty due to conflicting evidence). In our paper, we firstly apply evidential uncertainty in OOD detection for text classification tasks. We propose an inexpensive framework that adopts both auxiliary outliers and pseudo off-manifold samples to train the model with prior knowledge of a certain class, which has high vacuity for OOD samples. Extensive empirical experiments demonstrate that our model based on evidential uncertainty outperforms other counterparts for detecting OOD examples. Our approach can be easily deployed to traditional recurrent neural networks and fine-tuned pre-trained transformers.

Multi-label learning algorithms have attracted more and more attention as of recent. This is mainly because real-world data is generally associated with multiple and non-exclusive labels, which could correspond to different objects, scenes, actions, and attributes. In this paper, we consider the following challenging multi-label stream scenario: the new labels emerge continuously in the changing environments, and are assigned to the previous data. In this setting, data mining solutions must be able to learn the new concepts and avoid catastrophic forgetting simultaneously. We propose a novel continual and interactive feature distillation-based learning framework (CIFDM), to effectively classify instances with novel labels. We utilize the knowledge from the previous tasks to learn new knowledge to solve the current task. Then, the system compresses historical and novel knowledge and preserves it while waiting for new emerging tasks. CIFDM consists of three components: 1) a knowledge bank that stores the existing feature-level compressed knowledge, and predicts the observed labels so far; 2) a pioneer module that aims to learn and predict new emerged labels based on knowledge bank.; 3) an interactive knowledge compression function which is used to compress and transfer the new knowledge to the bank, and then apply the current compressed knowledge to initialize the label embedding of the pioneer for the next task.

Non-stationary data stream mining aims to classify large scale online instances that emerge continuously. The most apparent challenge compared with the offline learning manner is the issue of consecutive emergence of new categories, when tackling non-static categorical distribution. Non-stationary stream settings often appear in real-world applications, e.g., online classification in E-commerce systems that involves the incoming productions, or the summary of news topics on social networks (Twitter). Ideally, a learning model should be able to learn novel concepts from labeled data (in new tasks) and reduce the abrupt degradation of model performance on the old concept (also named catastrophic forgetting problem). In this work, we focus on improving the performance of the stream mining approach under the constrained resources, where both the memory resource of old data and labeled new instances are limited/scarce. We propose a simple yet efficient resource-constrained framework CLEAR to facilitate previous challenges during the one-pass stream mining. Specifically, CLEAR focuses on creating and calibrating the class representation (the prototype) in the embedding space. We first apply the contrastive-prototype learning on large amount of unlabeled data, and generate the discriminative prototype for each class in the embedding space. Next, for updating on new tasks/categories, we propose a drift estimation strategy to calibrate/compensate for the drift of each class representation, which could reduce the knowledge forgetting without storing any previous data. We perform experiments on public datasets (e.g., CUB200, CIFAR100) under stream setting, our approach is consistently and clearly better than many state-of-the-art methods, along with both the memory and annotation restriction.

Existing solutions to multi-task learning typically rely on manually enumerating multiple network architectures to find the optimal structure, which incurs a heavy design workload. In addition, extending these models to new tasks is difficult in many cases, since it often requires a network redesign for achieving the best performance. To overcome these limitations, in this paper, we propose a novel principle for multitask learning, which focuses on the learning process itself. For each task, we consider its feature as a state, and treat the learning problem as a state transformation process, which is driven by a task-specific gradient. Specifically, we introduce a Gradient Modification Unit (GMU), which consists of a Gradient Estimation Network (GEN) (shared among all tasks) and multiple tiny task-specific gradient correctors (one for each task). At each iteration, for any task T, the corresponding gradient corrector modifies the gradient estimated by the GEN to produce the desired task-specific gradient tensor that is applied to update the state of task T. Our solution has several benefits including automatic end-to-end learning of the optimal transformation process, simplification of network design and high expansibility to new tasks. We demonstrate the superiority of our approach over existing solutions on a variety of datasets, across both image classification and image retrieval tasks.

Extracting structured metadata from unstructured text in different domains is gaining strong attention from multiple research communities. In Political Science, these metadata play a significant role on studying intra and inter-state interactions between political entities. The process of extracting such metadata usually relies on domain specific ontologies and knowledge-based repositories. In particular, Political Scientists regularly use the well-defined ontology CAMEO, which is designed for capturing conflict and mediation relations. Since CAMEO repositories are currently human maintained, the high cost and extensive human effort associated with updating them makes it difficult to include new entries on a regular basis. This paper introduces HANKE: an innovative framework for automatically extracting knowledge representations from unstructured sources, in order to extend CAMEO ontology both in the same domain and towards other related domains in political science. HANKE combines Hierarchical Attention Networks as engine for identifying relevant structures in raw-text and the novel Frequency-Based Ranker approach to obtain a collection of candidate entries for CAMEO's repositories. To show the efficiency of the proposed framework, we evaluate its performance on capturing existing CAMEO representations in a soft-labelled dataset. We also empirically demonstrate the versatility and superiority of HANKE method by applying it to two case studies related to CAMEO extension on its actual domain and towards organized crime domain.

The problem of learning to generalize on unseen classes during the training step, also known as few-shot classification, has attracted considerable attention. Initialization based methods, such as the gradient-based model agnostic meta-learning (MAML) [1], tackle the few-shot learning problem by “learning to fine-tune”. The goal of these approaches is to learn proper model initialization, so that the classifiers for new classes can be learned from a few labeled examples with a small number of gradient update steps. Few shot meta-learning is well-known with its fast-adapted capability and accuracy generalization onto unseen tasks [2]. Learning fairly with unbiased outcomes is another significant hallmark of human intelligence, which is rarely touched in few-shot meta-learning. In this work, we propose a Primal-Dual Fair Meta-learning framework, namely PDFM, which learns to train fair machine learning models using only a few examples based on data from related tasks. The key idea is to learn a good initialization of a fair model's primal and dual parameters so that it can adapt to a new fair learning task via a few gradient update steps. Instead of manually tuning the dual parameters as hyperparameters via a grid search, PDFM optimizes the initialization of the primal and dual parameters jointly for fair meta-learning via a subgradient primal-dual approach. We further instantiate an example of bias controlling using decision boundary covariance (DBC) [3] as the fairness constraint for each task, and demonstrate the versatility of our proposed approach by applying it to classification on a variety of three realworld datasets. Our experiments show substantial improvements over the best prior work for this setting. Our code and datasets are available at https://github.com/charliezhaoyinpeng/PDFM.git.

Efficient audio scene classification is essential for smart sensing platforms such as robots, medical monitoring, surveillance, or autonomous vehicles. We propose a retrieval-based scene classification architecture that combines recurrent neural networks and attention to compute embeddings for short audio segments. We train our framework using a custom audio loss function that captures both the relevance of audio segments within a scene and that of sound events within a segment. Using experiments on real audio scenes, we show that we can discriminate audio scenes with high accuracy after listening in for less than a second. This preserves 93% of the detection accuracy obtained after hearing the entire scene.

Deep Neural Networks (DNNs) have primarily been demonstrated to be useful for closed-world classification problems where the number of categories is fixed. However, DNNs notoriously fail when tasked with label prediction in a non-stationary data stream scenario, which has the continuous emergence of the unknown or novel class (categories not in the training set). For example, new topics continually emerge in social media or e-commerce. To solve this challenge, a DNN should not only be able to detect the novel class effectively but also incrementally learn new concepts from limited samples over time. Literature that addresses both problems simultaneously is limited. In this paper, we focus on improving the generalization of the model on the novel classes, and making the model continually learn from only a few samples from the novel categories. Different from existing approaches that rely on abundant labeled instances to re-train/update the model, we propose a new approach based on Few Sample and Adversarial Representation Learning (FSAR). The key novelty is that we introduce the adversarial confusion term into both the representation learning and few-sample learning process, which reduces the over-confidence of the model on the seen classes, further enhance the generalization of the model to detect and learn new categories with only a few samples. We train the FSAR operated in two stages: first, FSAR learns an intra-class compacted and inter-class separated feature embedding to detect the novel classes; next, we collect a few labeled samples belong to the new categories, utilize episode-training to exploit the intrinsic features for few-sample learning. We evaluated FSAR on different datasets, using extensive experimental results from various simulated stream benchmarks to show that FSAR effectively outperforms current state-of-the-art approaches.

Typically, a traditional regression model over a data set is trained on instances by assuming a stationary distribution (the training data and test data has the same distribution). The model learned from the training set is later used to predict value of response-variable in future test instances. In this paper, we study the regression problem in a novelty problem setting, referred as a transfer learning involves training set and test set with different data distribution. Here, the training set has a biased data distribution with respect to the test set. The regression problem with the transfer learning approach aims to predict the dependent variable of test data, through utilizing the training data with the biased distribution. Availability of sufficient training data is of prime importance. Unfortunately, such problem settings are sparingly available in many real-word applications, such as you only have the flight delay information of DFW (DallasWorth) airport and prefer to predict the flight delay information of JFK (John F. Kennedy) airport. In our solution, we utilize relative density ratio to evaluate the difference between the data from different locations. We revise the relative density ratio estimation based on different location types, and propose an effective approach for predicting arrival delay time for commercial flights by geolocation aware relative kernel density estimation. Extensive experimental results on commercial flight datasets with different locations show that our approach effectively boosts the performance of other state-of-the art.

One of the key challenges of performing label predictions over a data stream is concerned with the emergence of instances belonging to unobserved (or novel) classes over time. Although existing studies have proposed various solutions to address this challenge, they mostly focus on streams with lowdimensional data and strongly rely on the intrinsic cohesion and separation data property, i.e., instances belonging to the same class are closer to each other (cohesion) than those belonging to different classes (separation) in the observed feature space, to detect instances from unknown classes. Unfortunately, such a property is typically not inherent in high-dimensional data such as images and texts. Thus, to perform classification and novel class detection on high-dimensional data streams, we need to address two main problems: 1) Finding a feature space that exhibit cohesion and separation properties, and 2) Training with limited amount of labeled data. In this paper, we propose a multi-task metric learning mechanism useful for identifying a latent space in which the cohesion and separation data property is valid and have designed a semi-supervised stream classifier called SIM based on this mechanism. We empirically measure the performance of SIM over multiple real-world image and text datasets, and demonstrate its superiority by comparing the performance with existing state-of-the-art frameworks.

Deep Neural Network (DNN) has been largely demonstrated to be effective for real-world classification problems. However, such model requires a huge amount of training samples to get more accurate result. When limited samples allowed for the training step, the model may perform weak generalization ability on the test set, especially when the novel/unseen class may occur during the test period (we call it open-set classification). This severely limits its further utility in many real-world large scale applications, such as the open-set image and text classification scenarios. In this paper, we focus on addressing this key challenge by developing a DNN based co-representation learning approach RLCN. It utilizes limited samples for training a model then applies it to classify normal instances and detect the emergence of novel class over time. The key novelty is that we design a weighted pairwise-constraint loss (WPC) function to learn an enhanced generalization and robust feature embedding, where the intra-class (same class) compactness and inter-class (different class) separation are achieved. Moreover, we apply the temperature scaling scheme on the softmax function to replace traditional softmax output in our open-world classifier to achieve the classification and novel class detection simultaneously. Our extensive empirical evaluation on benchmark datasets demonstrate the effectiveness of our framework compared to other competing techniques.

A primary challenge in label prediction over a data stream is the emergence of instances belonging to unknown or novel class over time. Traditionally, studies addressing this problem aim to detect such instances using cluster-based mechanisms. They typically assume that instances from the same class are closer to each other than those belonging to different classes in observed feature space. Unfortunately, this may not hold true in higher-dimensional feature space such as images. In recent years, Convolutional neural network (CNN) have emerged as a leading system to be employed in many real-world application. Yet, based on the assumption of closed world dataset with a fixed number of categories, CNN lacks robustness for novel class detection, so it is unclear on how such models can be used to deal with novel class instances along a high-dimensional image stream. In this paper, we focus on addressing this challenge by proposing an effective learning framework called CNN-based Prototype Ensemble (CPE) for novel class detection and correction. Our framework includes a prototype ensemble loss (PE) to improve the intra-class compactness and expand inter-class separateness in the output feature representation, thereby enabling the robustness of novel class detection. Moreover, we provide an incremental learning strategy which maintains a constant amount of exemplars to update the network, making it more practical for real-world application. We empirically demonstrate the effectiveness of our framework by comparing its performance over multiple realworld image benchmark data streams with existing state-of-theart data stream detection techniques. The implementation of CPE is on: https://github.com/Vitvicky/Convolutional-Net-PrototypeEnsemble

Good quality similarity metrics can significantly facilitate the performance of many large-scale, real-world applications. Existing studies have proposed various solutions to learn a Mahalanobis or bilinear metric in an online fashion by either restricting distances between similar (dissimilar) pairs to be smaller (larger) than a given lower (upper) bound or requiring similar instances to be separated from dissimilar instances with a given margin. However, these linear metrics learned by leveraging fixed bounds or margins may not perform well in real-world applications, especially when data distributions are complex. We aim to address the open challenge of “Online Adaptive Metric Learning” (OAML) for learning adaptive metric functions on-the-fly. Unlike traditional online metric learning methods, OAML is significantly more challenging since the learned metric could be non-linear and the model has to be self-adaptive as more instances are observed. In this paper, we present a new online metric learning framework that attempts to tackle the challenge by learning a ANN-based metric with adaptive model complexity from a stream of constraints. In particular, we propose a novel Adaptive-Bound Triplet Loss (ABTL) to effectively utilize the input constraints, and present a novel Adaptive Hedge Update (AHU) method for online updating the model parameters. We empirically validates the effectiveness and efficacy of our framework on various applications such as real-world image classification, facial verification, and image retrieval.

Under a newly introduced setting of multistream classification, two data streams are involved, which are referred to as source and target streams. The source stream continuously generates data instances from a certain domain with labels, while the target stream does the same task without labels from another domain. Existing approaches assume that domains for both data streams are identical, which is not quite true in real world scenario, since data streams from different sources may contain distinct features. Furthermore, obtaining labels for every instance in a data stream is often expensive and time-consuming. Therefore, it has become an important topic to explore whether labeled instances from other related streams can be helpful to predict those unlabeled instances in a given stream. Note that domains of source and target streams may have distinct features spaces and data distributions. Our objective is to predict class labels of data instances in the target stream by using the classifiers trained by the source stream.

Cheating in massive multiple online games (MMOGs) adversely affect the game's popularity and reputation among its users. Therefore, game developers invest large amount of efforts to detect and prevent cheats that provide an unfair advantage to cheaters over other naive users during game play. Particularly, MMOG clients share data with the server during game play. Game developers leverage this data to detect cheating. However, detecting cheats is challenging mainly due to the limited client-side information, along with unknown and complex cheating techniques. In this paper, we aim to leverage machine learning based models to predict cheats over encrypted game traffic during game play. Concretely, network game traffic during game play from each player can be used to determine whether a cheat is employed. A major challenge in developing such a prediction model is the availability of sufficient training data, which is sparingly available in practice. Game traffic obtained from a few known players can be easily labeled. However, if such players are not a good representation of the population (i.e., other players), then a supervised model trained on labeled game traffic from these set of players may not generalize well for the population. Here, we propose a scalable transfer learning approach to overcome the constraints of limited labeled data. Our empirical evaluation on a popular MMOG demonstrates significant improvement in cheat prediction compared to other competing methods.

In traditional machine learning, it is assumed that training data conforming to the stationary distribution of test data is readily available. Yet, such an assumption is not valid in practice due to a high cost of obtaining the truth value of data instances. This is particularly true when computing over non-stationary data streams. Recent studies in the multistream setting aim to address this issue by leveraging a stream of data with biased labeled instances (called the source stream) to train a suitable model for prediction over unlabeled instances (called the target stream). They use sampling bias correction techniques as a preprocessing step for estimating source instance weights for training a bias-corrected classifier useful to predict label of target data instances. In this regard, a recent framework proposes to utilize a Gaussian kernel model to estimate source instance weights. Unfortunately, it suffers from large computational time complexity and consequently deteriorates the rate at which streaming data is processed. In this paper, we address this issue by proposing a divide-and-conquer method suitable for simultaneously evaluating source instance weights and detecting changes in distribution over time. Our empirical results demonstrate a significant gain in execution time, compared to the previous approach, while achieving similar or better classification accuracy on real-world datasets.

A recently introduced problem setting, referred as multistream, involves two independent non-stationary data generating processes. One of them is called source stream, which generates continuous data instances with true output. And the other one called target stream, which generates data instances lacking of true output. Due to the nature of data streams, scholars have addressed prediction problems under scenarios such as covariate shift or concept drift in past studies by discussing one assumption while keeping others consistent. For example, it is assumed that the data distributions of training and testing data are similar, and true output values of the stream instances would be available soon. However, in practice these assumptions are not always valid. The multistream regression problem is to predict the output of target stream, using data instances and their true output from source stream. In this paper, we propose an approach of multistream regression by incorporating concept drift detection into covariate shift adaptation. Meanwhile, empirical evaluation on synthetic and real world datasets demonstrates the effectiveness of the proposed technique by competing with the state-of-the-art approaches. Experiment results indicate that our method significantly improved prediction performance compared to existing benchmark.

Automatic identification of geolocation mentioned in online news articles provide vital information for understanding associated events. While numerous open-source and commercial tools exist for geolocation extraction, they lack in reliable identification of fine-grained location, i.e., they identify location at country-level rather than a fine-grained city or locality level. The problem of location identification has been widely studied. Yet, most techniques depend on external knowledge-base or view the problem only in terms of Named Entity Recognition (NER), only to identify country-level location information. In this paper, we focus on news articles describing an event. A set of locations directly associated with the event are called focus locations. However, an event can occur only at a single location. Therefore, we aim to extract this location among focus locations, and call this as primary focus location. We propose a mechanism that utilizes the named entities to identify potential sentences containing focus locations, and then employ a supervised classification mechanism over sentence embedding to predict the primary focused geolocation. However, the main issue with such an approach is the unavailability of ground truth (i.e., whether words in a sentence is focus or non-focus) for training a classifier. In practice, labels from only a small number of news articles may be available for training due to high cost of manual labeling. If these articles are not a good representation of news articles in the wild, the classifier may not perform well. Therefore, we utilize an adaptation mechanism to overcome sampling bias in training data. Particularly, we train a classifier by using bias-corrected training data obtained from news articles published by an agency, while testing it on news articles published by a different agency. Our empirical results show superior performance compared to baseline approaches on real-world datasets consisting of news articles.

Data streams are continuous flows of data points. Novel class detection is an important part of data stream mining. A novel class is a newly emerged class that has not previously been modeled by the classifier over the input stream. This paper proposes deep embedding for novel class detection - a novel approach that combines feature learning using denoising autoencoding with novel class detection. A denoising autoencoder is a neural network with hidden layers aiming to reconstruct the input vector from a corrupted version. A nonparametric multidimensional change point detection approach is also proposed, to detect concept-drift (the change of data feature values over time). Experiments on several real datasets show that the approach significantly improves the performance of novel class detection.

Extracting a structured representation of political events from news reports is at the intersection of the computational and social sciences. A traditional approach is to use dictionary-based pattern lookups to identify actors and actions involved in potential events. A key complication of this approach is updating the dictionaries with new actors (e.g., when a new president takes office). Currently, the dictionaries are curated by humans, updated infrequently, and at a high cost. This means that tools dependent on the actor dictionaries (e.g., PETRARCH) overlook events when actors are missing in the dictionary. Since these tools use only the syntactic structure of the sentence (e.g., parse tree, etc.) for their event coding, missing actors will generate events which fail to capture actual political interaction. To overcome these issues, we propose a framework RePAIR to recommend new political actors in real-time from the political news articles with RSS feeds related to national/international politics across the globe. The framework identifies semantic structure of a sentence using an Automatic Content Extraction (ACE) method and uses a frequency based actor ranking algorithm to recommend the most frequent new political actors over multiple time windows. We also suggest the associated role of recommended new actors from the role of co-occurred political actors in the existing CAMEO actor dictionary. Further we integrate an external knowledge base (e.g., Wikipedia) into our framework to capture the evolving roles of existing actors over time and recommend new roles for them. Furthermore, we consider PETRARCH and BBN ACCENT event coders for actor recommendation, and a graph-based actor role recommendation using weighted label propagation as baselines and compare them with our framework. Experimental results show our approaches outperform them significantly.

Traditional data stream classification assumes that data is generated from a single non-stationary process. On the contrary, multistream classification problem involves two independent non-stationary data generating processes. One of them is the source stream that continuously generates labeled data. The other one is the target stream that generates unlabeled test data from the same domain. The distribution represented by the source stream data is biased compared to that of the target stream. Moreover, these streams may have asynchronous concept drifts between them. The multistream classification problem is to predict the class labels of target stream instances by utilizing labeled data from the source stream. This kind of scenario is often observed in real-world applications due to scarcity of labeled data. The only existing approach for multistream classification uses separate drift detection on the streams for addressing the asynchronous concept drift problem. If a concept drift is detected in any of the streams, it uses an expensive batch technique for data shift adaptation. These add significant execution overhead, and limit its usability. In this paper, we propose an efficient solution for multistream classification by fusing drift detection into online data shift adaptation. We study the theoretical convergence rate and computational complexity of the proposed approach. Moreover, empirical results on benchmark data sets indicate significantly improved performance over the baseline methods.

Traditional data stream classification techniques assume that the stream of data is generated from a single non-stationary process. On the contrary, a recently introduced problem setting, referred to as Multistream Classification involves two independent non-stationary data generating processes. One of them is the source stream that continuously generates labeled data instances. The other one is the target stream that generates unlabeled test data instances from the same domain. The distributions represented by the source stream data is biased compared to that of the target stream. Moreover, these streams may have asynchronous concept drifts between them. The multistream classification problem is to predict the class labels of target stream instances, while utilizing labeled data available from the source stream. In this paper, we propose an efficient solution for multistream classification by fusing drift detection into online data shift adaptation. Experiment results on benchmark data sets indicate significantly improved performance over the only existing approach for multistream classification.

Limited access to supervised information may forge scenarios in real-world data mining applications, where training and test data are interconnected by a covariate shift, i.e., having equal class conditional distribution with unequal covariate distribution. Traditional data mining techniques assume that both training and test data represent an identical distribution, therefore suffer in presence of a covariate shift. Kernel Mean Matching (KMM) is a well known approach that addresses covariate shift by weighing training instances appropriately. However, it has time complexity cubic in the size of training data, which is computationally impractical for large or streaming datasets due to limited scalability. In this paper, we present a sampling-based algorithm to address the limited scalability problem of KMM. Moreover, we show that the approach is highly parallelizable, and therefore propose a distributed algorithm for estimating training instance weights efficiently using Spark. Experiment results on benchmark datasets show that the proposed approach achieves competitive estimation accuracy within much lower execution time compared to the KMM algorithm. Moreover, it indicates that larger size of training data results into a higher accuracy with minimal effect on execution time of the proposed approach.

A typical data stream classification involves predicting label of data instances generated from a non-stationary process. Studies in the past decade have focused on this problem setting to address various challenges such as concept drift and concept evolution. Most techniques assume availability of class labels associated with unlabeled data instances, soon after label prediction, for further training and drift detection. Moreover, training and test data distributions are assumed to be similar. These assumptions are not always true in practice. For instance, a semi-supervised setting that aims to utilize only a fraction of labels may induce bias during data selection. Consequently, the resulting data distribution of training and test instances may differ. In this paper, we present a novel stream classification problem setting involving two independent non-stationary data generating processes, relaxing the above assumptions. A source stream continuously generates labeled data instances whose distribution is biased compared to that of a target stream which generates unlabeled data instances from the same domain. The problem, we call Multistream Classification, is to predict the class labels of data instances in the target stream, while utilizing labels available on the source stream. Since concept drift can occur asynchronously on these two streams, we design an adaptive framework that uses a technique for supervised concept drift detection in the biased source stream, and unsupervised concept drift detection in the target stream. A weighted ensemble of classifiers is updated after each drift detection on either streams, while utilizing a bias correction mechanism that leverage source information to predict labels of target instances whenever necessary. We empirically evaluate the multistream classifier's performance on both real-world and synthetic datasets, while comparing with various baseline methods and its variants.

To decide if an update to a data stream classifier is necessary, existing sliding window based techniques monitor classifier performance on recent instances. If there is a significant change in classifier performance, these approaches determine a chunk boundary, and update the classifier. However, monitoring classifier performance is costly due to scarcity of labeled data. In our previous work, we presented a semi-supervised framework SAND, which uses change detection on classifier confidence to detect a concept drift. Unlike most approaches, it requires only a limited amount of labeled data to detect chunk boundaries and to update the classifier. However, SAND is expensive in terms of execution time due to exhaustive invocation of the change detection module. In this paper, we present an efficient framework, which is based on the same principle as SAND, but exploits dynamic programming and executes the change detection module selectively. Moreover, we provide theoretical justification of the confidence calculation, and show effect of a concept drift on subsequent confidence scores. Experiment results show efficiency of the proposed framework in terms of both accuracy and execution time.

Many real-world applications exhibit scenarios where distributions represented by training and test data are not similar, but related by a covariate shift, i.e., having equal class conditional distribution with unequal covariate distribution. Traditional data mining techniques suffer to learn a good predictive model in the presence of covariate shift. Recent studies have proposed approaches to address this challenge by weighing training instances based on density ratio between test and training data distributions. Kernel Mean Matching (KMM) is a well known method for estimating density ratio, but has time complexity cubic in the size of training data. Therefore, KMM is not suitable in real-world applications, especially in cases where the predictive model needs to be updated periodically with large training data. We address this challenge by taking fixed-size samples from training and test data, performing independent computations on these samples, and combining the results to obtain overall density ratio estimates. Our empirical evaluation demonstrates a large gain in execution time, while also achieving competitive accuracy on numerous benchmark datasets.

The challenge of deriving insights from the Internet of Things (IoT) has been recognized as one of the most exciting and key opportunities for both academia and industry. Advanced analysis of big data streams from sensors and devices is bound to become a key area of data mining research as the number of applications requiring such processing increases. Dealing with the evolution over time of such data streams, i.e., with concepts that drift or change completely, is one of the core issues in IoT stream mining. This tutorial is a gentle introduction to mining IoT big data streams. The first part introduces data stream learners for classification, regression, clustering, and frequent pattern mining. The second part deals with scalability issues inherent in IoT applications, and discusses how to mine data streams on distributed engines such as Spark, Flink, Storm, and Samza.

Streaming data is one of the attention receiving sources for concept-evolution studies. When a new class occurs in the data stream it can be considered as a new concept and so the concept-evolution. One attractive problem occurring in the concept-evolution studies is the recurring classes from our previous study. In data streams, a class can disappear and reappear after a while. Existing studies on data stream classification techniques either misclassify the recurring class or falsely identify the recurring classes as novel classes. Because of the misclassification or false novel classification, the error rates increases on those studies. In this paper we address the problem by defining a novel ensemble technique “class-based” ensemble which replaces the traditional “chunk-based” approach in order to detect the recurring classes. We discuss the details of two different approaches in class-based ensemble and explain and compare them in detail. Different than the previous studies in the field, we also prove the superiority of both “class-based” ensemble method over state-of-art techniques via empirical approach on a number of benchmark data sets including Web comments as text mining challenge.

In the case of a graphical model, machine learning algorithms used to evaluate a query can be broadly classified into exact and approximate inference algorithms. Exact inference algorithms use only network parameters to evaluate a query. However, these algorithms are typically intractable on large networks due to exponential time and space complexity. Approximate inference algorithms are widely used in practice to overcome this constraint, with a trade-off in accuracy. It includes sampling and propagation-based algorithms. These approximate algorithms may also suffer from scalability issues if applied on large networks, for achieving higher accuracy. To address this challenge, we have designed and implemented several MapReduce-based distributed versions of a specific type of approximate inference algorithm called Adaptive Importance Sampling (AIS). We compare and evaluate the proposed approaches using benchmark networks. Experimental results show that our proposed approaches achieve significant scaleup and speedup compared to the sequential method, while achieving similar accuracy asymptotically.

Anomaly detection refers to the identification of patterns in a dataset that do not conform to expected patterns. Depending on the domain, the non-conformant patterns are assigned various tags, e.g. anomalies, outliers, exceptions, malwares and so forth. Online anomaly detection aims to detect anomalies in data flowing in a streaming fashion. Such stream data is commonplace in today's cloud data centers that house a large array of virtual machines(VM) producing vast amounts of performance data in real-time. Sophisticated detection mechanism will likely entail collation of data from heterogeneous sources with diversified data format and semantics. Therefore, detection of performance anomaly in this context requires a distributed framework with high throughput and low latency. Apache Spark is one such framework that represents the bleeding-edge amongst its contemporaries. In this paper, we have taken up the challenge of anomaly detection in VMware based cloud data centers. We have employed a Chi-square based statistical anomaly detection technique in Spark. We have demonstrated how to take advantage of the high processing power of Spark to perform anomaly detection on heterogeneous data using statistical techniques. Our approach is optimally designed to cope with the heterogeneity of input data streams and the experiments we conducted testify to its efficacy in online anomaly detection.

A graphical model represents the data distribution of a data generating process and inherently captures its feature relationships. This stochastic model can be used to perform inference, to calculate posterior probabilities, in various applications such as classification. Exact inference algorithms are known to be intractable on large networks due to exponential time and space complexity. Approximate inference algorithms are instead widely used in practice to overcome this constraint, with a trade off in accuracy. Stochastic sampling is one such method where an approximate probability distribution is empirically evaluated using various sampling techniques. However, these algorithms may still suffer from scalability issues on large and complex networks. To address this challenge, we have designed and implemented several MapReduce based distributed versions of a specific type of approximate inference algorithm called Adaptive Importance Sampling (AIS). We compare and evaluate the proposed approaches using benchmark networks. Experimental result shows that our approach achieves significant scaleup and speedup compared to the sequential algorithm, while achieving similar accuracy asymptotically.

Stream mining has gained popularity in recent years due to the availability of numerous data streams from sources such as social media and sensor networks. Data mining on such continuous streams possess a variety of challenges including concept drift and unbounded stream length. Traditional data mining approaches to these problems have difficulty incorporating relational domain knowledge and feature relationships, which can be used to improve the accuracy of a classifier. In this work, we model large data streams using statistical relational learning techniques for classification, in particular, we use a Markov Logic Network to capture relational features in structured data and show that this approach performs better for supervised learning than current state-of-the-art approaches. Additionally, we evaluate our approach with semi-supervised learning scenarios, where class labels are only partially available during training.

Data stream classification poses many challenges to the data mining community. In this paper, we address four such major challenges, namely, infinite length, concept-drift, concept-evolution, and feature-evolution. Since a data stream is theoretically infinite in length, it is impractical to store and use all the historical data for training. Concept-drift is a common phenomenon in data streams, which occurs as a result of changes in the underlying concepts. Concept-evolution occurs as a result of new classes evolving in the stream. Feature-evolution is a frequently occurring process in many streams, such as text streams, in which new features (i.e., words or phrases) appear as the stream progresses. Most existing data stream classification techniques address only the first two challenges, and ignore the latter two. In this paper, we propose an ensemble classification framework, where each classifier is equipped with a novel class detector, to address concept-drift and concept-evolution. To address feature-evolution, we propose a feature set homogenization technique. We also enhance the novel class detection module by making it more adaptive to the evolving stream, and enabling it to detect more than one novel class at a time. Comparison with state-of-the-art data stream classification techniques establishes the effectiveness of the proposed approach.

Concept-evolution has recently received a lot of attention in the context of mining data streams. Concept-evolution occurs when a new class evolves in the stream. Although many recent studies address this issue, most of them do not consider the scenario of recurring classes in the stream. A class is called recurring if it appears in the stream, disappears for a while, and then reappears again. Existing data stream classification techniques either misclassify the recurring class instances as another class, or falsely identify the recurring classes as novel. This increases the prediction error of the classifiers, and in some cases causes unnecessary waste in memory and computational resources. In this paper we address the recurring class issue by proposing a novel "class-based" ensemble technique, which substitutes the traditional "chunk-based" ensemble approaches and correctly distinguishes between a recurring class and a novel one. We analytically and experimentally confirm the superiority of our method over state-of-the-art techniques.

Concept-evolution is one of the major challenges in data stream classification, which occurs when a new class evolves in the stream. This problem remains unaddressed by most state-of-the-art techniques. A recurring class is a special case of concept-evolution. This special case takes place when a class appears in the stream, then disappears for a long time, and again appears. Existing data stream classification techniques that address the concept-evolution problem, wrongly detect the recurring classes as novel class. This creates two main problems. First, much resource is wasted in detecting a recurring class as novel class, because novel class detection is much more computationally- and memory-intensive, as compared to simply recognizing an existing class. Second, when a novel class is identified, human experts are involved in collecting and labeling the instances of that class for future modeling. If a recurrent class is reported as novel class, it will be only a waste of human effort to find out whether it is really a novel class. In this paper, we address the recurring issue, and propose a more realistic novel class detection technique, which remembers a class and identifies it as "not novel" when it reappears after a long disappearance. Our approach has shown significant reduction in classification error over state-of-the-art stream classification techniques on several benchmark data streams.

Cloud computing is rapidly growing in popularity as a solution for processing and retrieving huge amounts of data over clusters of inexpensive commodity hardware. The most common data model utilized by cloud computing software is the NoSQL data model. While this data model is extremely scalable, it is much more efficient for simple retrievals and scans than for the complex analytical queries typical in a relational database model. In this paper, we evaluate emerging cloud computing technologies using a representative use case. Our use case involves analyzing telecommunications logs for performance monitoring and quality assurance. Clearly, the size of such logs is growing exponentially as more devices communicate more frequently and the amount of data being transferred steadily increases. We analyze potential solutions to provide a scalable database which supports both retrieval and analysis. We will investigate and analyze all the major open source cloud computing solutions and designs. We then choose the most applicable subset of these technologies for experimentation. We provide a performance evaluation of these products, and we analyze our results and make recommendations. This paper provides a comprehensive survey of technologies for scalable data processing and an in-depth performance evaluation of these technologies.

Semantic web is an emerging area to augment human reasoning. Various technologies are being developed in this arena which have been standardized by the World Wide Web Consortium (W3C). One such standard is the Resource Description Framework (RDF). Semantic web technologies can be utilized to build efficient and scalable systems for Cloud Computing. With the explosion of semantic web technologies, large RDF graphs are common place. This poses significant challenges for the storage and retrieval of RDF graphs. Current frameworks do not scale for large RDF graphs and as a result do not address these challenges. In this paper, we describe a framework that we built using Hadoop to store and retrieve large numbers of RDF triples by exploiting the cloud computing paradigm. We describe a scheme to store RDF data in Hadoop Distributed File System. More than one Hadoop job (the smallest unit of execution in Hadoop) may be needed to answer a query because a single triple pattern in a query cannot simultaneously take part in more than one join in a single Hadoop job. To determine the jobs, we present an algorithm to generate query plan, whose worst case cost is bounded, based on a greedy approach to answer a SPARQL Protocol and RDF Query Language (SPARQL) query. We use Hadoop's MapReduce framework to answer the queries. Our results show that we can store large RDF graphs in Hadoop clusters built with cheap commodity class hardware. Furthermore, we show that our framework is scalable and efficient and can handle large amounts of RDF data, unlike traditional approaches.

Most existing data stream classification techniques ignore one important aspect of stream data: arrival of a novel class. We address this issue and propose a data stream classification technique that integrates a novel class detection mechanism into traditional classifiers, enabling automatic detection of novel classes before the true labels of the novel class instances arrive. Novel class detection problem becomes more challenging in the presence of concept-drift, when the underlying data distributions evolve in streams. In order to determine whether an instance belongs to a novel class, the classification model sometimes needs to wait for more test instances to discover similarities among those instances. A maximum allowable wait time Tcis imposed as a time constraint to classify a test instance. Furthermore, most existing stream classification approaches assume that the true label of a data point can be accessed immediately after the data point is classified. In reality, a time delay Tlis involved in obtaining the true label of a data point since manual labeling is time consuming. We show how to make fast and correct classification decisions under these constraints and apply them to real benchmark data. Comparison with state-of-the-art stream classification techniques prove the superiority of our approach.

The problem of data stream classification is challenging because of many practical aspects associated with efficient processing and temporal behavior of the stream. Two such well studied aspects are infinite length and concept-drift. Since a data stream may be considered a continuous process, which is theoretically infinite in length, it is impractical to store and use all the historical data for training. Data streams also frequently experience concept-drift as a result of changes in the underlying concepts. However, another important characteristic of data streams, namely, concept-evolution is rarely addressed in the literature. Concept-evolution occurs as a result of new classes evolving in the stream. This paper addresses concept-evolution in addition to the existing challenges of infinite-length and concept-drift. In this paper, the concept-evolution phenomenon is studied, and the insights are used to construct superior novel class detection techniques. First, we propose an adaptive threshold for outlier detection, which is a vital part of novel class detection. Second, we propose a probabilistic approach for novel class detection using discrete Gini Coefficient, and prove its effectiveness both theoretically and empirically. Finally, we address the issue of simultaneous multiple novel class occurrence, and provide an elegant solution to detect more than one novel classes at the same time. We also consider feature-evolution in text data streams, which occurs because new features (i.e., words) evolve in the stream. Comparison with state-of-the-art data stream classification techniques establishes the effectiveness of the proposed approach.

RDFKB (Resource Description Framework Knowledge Base) is a solution for managing, persisting and querying semantic web knowledge. RDFKB provides a flexible data management schema that allows additions, deletions, and updates at all levels in the data model. RDFKB also supports 1) knowledge inference, 2) provenance and lineage, 3) probabilities and uncertainty reasoning, 4) trust factors, 5) dataset linkage and ontology alignment. We will show through a variety of use cases and experiments that RDFKB enables each of these tasks. We will also show that RDFKB outperforms all other semantic web repositories through experiments using 26 queries against 2 accepted benchmark datasets.

Resolving semantic heterogeneity across distinct data sources remains a highly relevant problem in the GIS domain requiring innovative solutions. Our approach, called GSim, semantically aligns tables from respective GIS databases by first choosing attributes for comparison. We then examine their instances and calculate a similarity value between them called entropy-based distribution (EBD) by combining two separate methods. Our primary method discerns the geographic types from instances of compared attributes. If geographic type matching is not possible, we then apply a generic schema matching method which employs normalized Google distance. We show the effectiveness of our approach over the traditional N-gram approach across multi-jurisdictional datasets by generating impressive results.

RDFKB (Resource Description Framework Knowledge Base) is a relational database system for RDF datasets which supports inference and knowledge management. Significant research has addressed improving the performance of queries against RDF datasets. Generally, this research has not addressed queries against inferred knowledge. Solutions which do support inference queries have done so as part of query processing. Ontologies define the rules that govern inference for RDF datasets. These inference rules can be applied to RDF datasets to derive additional facts through methods such as subsumption, symmetry and transitive closure. We propose a framework that supports inference at data storage time rather than as part of query processing. The dataset is increased to include all knowledge whether explicitly specified or derived through inference with a negligible overhead. Queries against inferred data are simplified, and performance is increased.

The enthusiastic acceptance of Resource Description Framework (RDF) as a data model has given birth to a new data storage paradigm, namely, the RDF Graph model. The pool of modeling and visualization tools available for RDF stores is limited due to the technology being in its fledgling stage. The work presented in this paper, called R2D (RDF-to-Database) is an effort to make available, to RDF data stores, the abundance of relational tools that are currently in the market. This is done in the form of a JDBC wrapper around RDF Stores that presents a relational view of the stores and their data to the modeling and visualization tools. This paper presents key R2D functionalities and mapping constructs, procedures for every stage of R2D deployment, and sample results in the form of screenshots and performance graphs.

The emergence of Semantic Web technologies and standards such as Resource Description Framework (RDF) has introduced novel data storage models such as the RDF Graph Model. In this paper, we present a research effort called R2D, which attempts to bridge the gap between RDF and RDBMS concepts by presenting a relational view of RDF data stores. Thus, R2D is essentially a relational wrapper around RDF stores that aims to make the variety of stable relational tools that are currently in the market available to RDF stores without data duplication and synchronization issues.

The alignment of separate ontologies by matching related concepts continues to attract great attention within the database and artificial intelligence communities, especially since semantic heterogeneity across data sources remains a widespread and relevant problem. In particular, the Geographic Information System (GIS) domain presents unique forms of semantic heterogeneity that require a variety of matching approaches.

Recent approaches in classifying evolving data streams are based on supervised learning algorithms, which can be trained with labeled data only. Manual labeling of data is both costly and time consuming. Therefore, in a real streaming environment, where huge volumes of data appear at a high speed, labeled data may be very scarce. Thus, only a limited amount of training data may be available for building the classification models, leading to poorly trained classifiers. We apply a novel technique to overcome this problem by building a classification model from a training set having both unlabeled and a small amount of labeled instances. This model is built as micro-clusters using semi-supervised clustering technique and classification is performed with kappa-nearest neighbor algorithm. An ensemble of these models is used to classify the unlabeled data. Empirical evaluation on both synthetic data and real botnet traffic reveals that our approach, using only a small amount of labeled data for training, outperforms state-of-the-art stream classification algorithms that use twenty times more labeled data than our approach.

In this paper, we study various K nearest neighbor (KNN) algorithms and present a new KNN algorithm based on evidence theory. We introduce global frequency estimation of prior probability (GE) and local frequency estimation of prior probability (LE). A GE for a class is the prior probability of the class across the whole training data space based on frequency estimation; on the other hand, a LE for a class in a particular neighborhood is the prior probability of the class in this neighborhood space based on frequency estimation. By considering the difference between the GE and the LE of each class, we present a solution to the imbalanced data problem in some degree without doing re-sampling. We compare our algorithm with other KNN algorithms using two benchmark datasets. Results show that our KNN algorithm outperforms other KNN algorithms, including basic evidence based KNN.

Previous work in hierarchical categorization focuses on the hierarchical perceptron (Hieron) algorithm. Hierarchical perceptron works on the principles of the perceptron,that is each class label in the hierarchy has an associated weight vector. To account for the hierarchy, we begin at the root of the tree and sum all weights to the target label.We make a prediction by considering the label that yields the maximum inner product of its feature set with its path-summed weights. Learning is done by adjusting the weights along the path from the predicted node to the correct node by a specific loss function that adheres to the large margin principal. There are several problems with applying this approach to a multiple class problem. In many cases we could end up punishing weights that gave a correct prediction, because the algorithm can only take a single case at a time. In this paper we present an extended hierarchical perceptron algorithm capable of solving the multiple categorization problem (MultiHieron). We introduce new aggregate loss function for multiple label learning. We make weight updates simultaneously instead of serially. Then, significant improvement over the basic Hieron algorithm is demonstrated on the aviation safety reporting system (ASRS) flight anomaly database and OntoNews corpus using both flat and hierarchical categorization metrics.

Service discovery is the crucial phase in the emerging Geospatial Semantic Web to select functionally similar services for the user query. Quality of Service (QoS) based service discovery, popularly studied in traditional Web Services, applies also to Geospatial Web Services. QoS allows service clients to fine-tune their search according to their specific needs and criteria. In high-performance service-based geospatial applications, it becomes an interesting research challenge to identify geospatial parameters to further improve the search process. In this paper we have proposed a set of geospatial criteria that can be used alongside the regular QoS parameters in service discovery and invocation. We show that using this novel approach of incorporating domain-specific drill-down information in addition to the commonly used QoS parameters yield more accurate and trustable Web services platform. We use the proposed geospatial parameters as performance metrics in the experimental evaluation of our application. The parameters reflect geospatial data quality attributes already standardized and well-studied in geospatial literature.

An adaptive probe-based optimization technique is developed and demonstrated in the context of an Internet-based distributed database environment. More and more common are database systems, which are distributed across servers communicating via the Internet where a query at a given site might require data from remote sites. Optimizing the response time of such queries is a challenging task due to the unpredictability of server performance and network traffic at the time of data shipment; this may result in the selection of an expensive query plan using a static query optimizer. We constructed an experimental setup consisting of two servers running the same DBMS connected via the Internet. Concentrating on join queries, we demonstrate how a static query optimizer might choose an expensive plan by mistake. This is due to the lack of a priori knowledge of the run-time environment, inaccurate statistical assumptions in size estimation, and neglecting the cost of remote method invocation. These shortcomings are addressed collectively by proposing a probing mechanism. Furthermore, we extend our mechanism with an adaptive technique that detects sub-optimality of a plan during query execution and attempts to switch to the cheapest plan while avoiding redundant work and imposing little overhead. An implementation of our run-time optimization technique for join queries was constructed in the Java language and incorporated into an experimental setup. The results demonstrate the superiority of our probe-based optimization over a static optimization.