Because of transportation planning, traffic management and dispatch optimization importance, the passenger origin-destination prediction has become one of the most important requirements for intelligent transportation systems management. In this paper, we propose a model to predict the origin and destination of travels which will occur in the next specified time window. In order to extract meaningful travel flows we use K-means clustering in four-dimensional space with maximum cluster size limitation for origin and destination. Because of large number of clusters, we use non-negative matrix factorization to decrease the number of travel clusters. We also use a stacked recurrent neural network model to predict travels count in each cluster. Comparing our results with other existing models show that our proposed model has 5-7% lower mean absolute percentage error (MAPE) for 1-hour time window, and 14% lower MAPE for 30-minute time window.

Information systems have widely been the target of malware attacks. Traditional signature-based malicious program detection algorithms can only detect known malware and are prone to evasion techniques such as binary obfuscation, while behavior-based approaches highly rely on the malware training samples and incur prohibitively high training cost. To address the limitations of existing techniques, we propose MatchGNet, a heterogeneous Graph Matching Network model to learn the graph representation and similarity metric simultaneously based on the invariant graph modeling of the program's execution behaviors. We conduct a systematic evaluation of our model and show that it is accurate in detecting malicious program behavior and can help detect malware attacks with less false positives. MatchGNet outperforms the state-of-the-art algorithms in malware detection by generating 50% less false positives while keeping zero false negatives.

Daniel Jiwoong Im 1, Yibo Jiang 2, and Nakul Verma 3 1 Janelia Research Campus, HHMI, Virgina 2 Harvard University, Massachusetts 3 Columbia University, New York Abstract Meta learning has emerged as an important framework for learning new tasks from just a few examples. The success of any meta-learning model depends on (i) its fast adaptation to new tasks, as well as (ii) having a shared representation across similar tasks. Here we extend the model-agnostic meta-learning (MAML) framework introduced by Finn et al. (2017) to achieve improved performance by analyzing the temporal dynamics of the optimization procedure via the Runge-Kutta method. This method enables us to gain fine-grained control over the optimization and helps us achieve both the adaptation and representation goals across tasks. By leveraging this refined control, we demonstrate that there are multiple principled ways to update MAML and show that the classic MAML optimization is simply a special case of second order Runge-Kutta method that mainly focuses on fast-adaptation. Experiments on benchmark classification, regression and reinforcement learning tasks show that this refined control helps attain improved results. 1 Introduction Building an intelligent system that can learn quickly on a new task with few examples or few experiences is one of the central goals of machine learning. Achieving this goal requires an agent that learns continuously while having the ability to adapt to new tasks with limited data. Meta-learning (Biggs, 1985) has emerged as a compelling framework that strives to attain this challenging goal. There are two main approaches to meta-learning: learning-to-optimize and learning-to-initialize the meta-model (usually encoded as deep network).

Generative models of graph structure have applications in biology and social sciences. The state of the art is GraphRNN, which decomposes the graph generation process into a series of sequential steps. While effective for modest sizes, it loses its permutation invariance for larger graphs. Instead, we present a permutation invariant latent-variable generative model relying on graph embeddings to encode structure. Using tools from the random graph literature, our model is highly scalable to large graphs with likelihood evaluation and generation in $O(|V | + |E|)$.

ABSTRACT W e address the problem of simultaneously learning a k -means clustering and deep feature representation from unlabelle d data, which is of interest due to the potential of deep k -means to outperform traditional two-step feature extraction and shallow-clustering strategies. W e achieve this by develop ing a gradient-estimator for the non-differentiable k -means objective via the Gumbel-Softmax reparameterisation trick. In contrast to previous attempts at deep clustering, our concr ete k -means model can be optimised with respect to the canonical k -means objective and is easily trained end-to-end without resorting to alternating optimisation. W e demonstrate the efficacy of our method on standard clustering benchmarks. Index T erms-- Deep Clustering, Unsupervised Learning, Gradient Estimator 1. INTRODUCTION Clustering is a fundamental task in unsupervised machine learning, and one with numerous applications.

Selecting hyperparameters for unsupervised learning problems is difficult in general due to the lack of ground truth for validation. However, this issue is prevalent in machine learning, especially in clustering problems with examples including the Lagrange multipliers of penalty terms in semidefinite programming (SDP) relaxations and the bandwidths used for constructing kernel similarity matrices for Spectral Clustering. Despite this, there are not many provable algorithms for tuning these hyperparameters. In this paper, we provide a unified framework with provable guarantees for the above class of problems. We demonstrate our method on two distinct models. First, we show how to tune the hyperparameters in widely used SDP algorithms for community detection in networks. In this case, our method can also be used for model selection. Second, we show the same framework works for choosing the bandwidth for the kernel similarity matrix in Spectral Clustering for subgaussian mixtures under suitable model specification. In a variety of simulation experiments, we show that our framework outperforms other widely used tuning procedures in a broad range of parameter settings.

Deep neural networks (DNNs) build high-level intelligence on low-level raw features. Understanding of this high-level intelligence can be enabled by deciphering the concepts they base their decisions on, as human-level thinking. In this paper, we study concept-based explainability for DNNs in a systematic framework. First, we define the notion of completeness, which quantifies how sufficient a particular set of concepts is in explaining a model's prediction behavior. Based on performance and variability motivations, we propose two definitions to quantify completeness. We show that under degenerate conditions, our method is equivalent to Principal Component Analysis. Next, we propose a concept discovery method that considers two additional constraints to encourage the interpretability of the discovered concepts. We use game-theoretic notions to aggregate over sets to define an importance score for each discovered concept, which we call ConceptSHAP. On specifically-designed synthetic datasets and real-world text and image datasets, we validate the effectiveness of our framework in finding concepts that are complete in explaining the decision, and interpretable.

For complex nonlinear supervised learning models, assessing the relevance of input variables or their interactions is not straightforward due to the lack of a direct measure of relevance, such as the regression coefficients in generalized linear models. One can assess the relevance of input variables locally by using the mean prediction or its derivative, but this disregards the predictive uncertainty. In this work, we present a Bayesian method for identifying relevant input variables with main effects and interactions by differentiating the Kullback-Leibler divergence of predictive distributions. The method averages over local measures of relevance and has a conservative property that takes into account the uncertainty in the predictive distribution. Our empirical results on simulated and real data sets with nonlinearities demonstrate accurate and efficient identification of relevant main effects and interactions compared to alternative methods.

--Recently algorithms incorporating second order curvature information have become popular in training neural networks. The Nesterov's Accelerated Quasi-Newton (NAQ) method has shown to effectively accelerate the BFGS quasi-Newton method by incorporating the momentum term and Nesterov's accelerated gradient vector . A stochastic version of NAQ method was proposed for training of large-scale problems. This paper proposes a stochastic variance reduced Nesterov's Accelerated Quasi-Newton method in full (SVR-NAQ) and limited (SVR-LNAQ) memory forms. The performance of the proposed method is evaluated in T ensorflow on four benchmark problems - two regression and two classification problems respectively. The results show improved performance compared to conventional methods.

Machine learning classifiers often stumble over imbalanced datasets where classes are not equally represented. This inherent bias towards the majority class may result in low accuracy in labeling minority class. Imbalanced learning is prevalent in many real world applications, such as medical research, network intrusion detection, and fraud detection in credit card transaction, etc. A good number of research works have been reported to tackle this challenging problem. For example, SMOTE (Synthetic Minority Over-sampling TEchnique) and ADASYN (ADAptive SYNthetic sampling approach) use oversampling techniques to balance the skewed datasets. In this paper, we propose a novel method which combines a Weighted Oversampling Technique and ensemble Boosting method to improve the classification accuracy of minority data without sacrificing the accuracy of majority class. WOTBoost adjust its oversampling strategy at each round of boosting to synthesize more targeted minority data samples. The adjustment is enforced using a weighted distribution. We compared WOTBoost with other 4 classification models (i.e. decision tree, SMOTE + decision tree, ADASYN + decision tree, SMOTEBoost) extensively on 18 public accessible imbalanced datasets. WOTBoost achieved the best G mean on 6 datasets and highest AUC score on 7 datasets.