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1. Multidimensional Uncertainty-Aware Evidential Neural Networks

   Hu, Yibo; Ou, Yuzhe; Zhao, Xujiang; Cho, Jin-Hee; Chen, Feng (June 2021, Proceedings of the Thirty-Fifth AAAI Conference on Artificial Intelligence)

   null (Ed.)

   Traditional deep neural networks (NNs) have significantly contributed to the state-of-the-art performance in the task of classification under various application domains. However, NNs have not considered inherent uncertainty in data associated with the class probabilities where misclassification under uncertainty may easily introduce high risk in decision making in real-world contexts (e.g., misclassification of objects in roads leads to serious accidents). Unlike Bayesian NN that indirectly infer uncertainty through weight uncertainties, evidential NNs (ENNs) have been recently proposed to explicitly model the uncertainty of class probabilities and use them for classification tasks. An ENN offers the formulation of the predictions of NNs as subjective opinions and learns the function by collecting an amount of evidence that can form the subjective opinions by a deterministic NN from data. However, the ENN is trained as a black box without explicitly considering inherent uncertainty in data with their different root causes, such as vacuity (i.e., uncertainty due to a lack of evidence) or dissonance (i.e., uncertainty due to conflicting evidence). By considering the multidimensional uncertainty, we proposed a novel uncertainty-aware evidential NN called WGAN-ENN (WENN) for solving an out-of-distribution (OOD) detection problem. We took a hybrid approach that combines Wasserstein Generative Adversarial Network (WGAN) with ENNs to jointly train a model with prior knowledge of a certain class, which has high vacuity for OOD samples. Via extensive empirical experiments based on both synthetic and real-world datasets, we demonstrated that the estimation of uncertainty by WENN can significantly help distinguish OOD samples from boundary samples. WENN outperformed in OOD detection when compared with other competitive counterparts 

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2. Augmentation by Counterfactual Explanation--Fixing an Overconfident Classifier

   Sumedha Singla; Nihal Murali; Forough Arabshahi; Sofia Triantafyllou; Kayhan Batmanghelich (January 2022, IEEE Winter Conference on Applications of Computer Vision)

   A highly accurate but overconfident model is ill-suited for deployment in critical applications such as healthcare and autonomous driving. The classification outcome should reflect a high uncertainty on ambiguous in-distribution samples that lie close to the decision boundary. The model should also refrain from making overconfident decisions on samples that lie far outside its training distribution, far-out-of-distribution (far-OOD), or on unseen samples from novel classes that lie near its training distribution (near-OOD). This paper proposes an application of counterfactual explanations in fixing an over-confident classifier. Specifically, we propose to fine-tune a given pre-trained classifier using augmentations from a counterfactual explainer (ACE) to fix its uncertainty characteristics while retaining its predictive performance. We perform extensive experiments with detecting far-OOD, near-OOD, and ambiguous samples. Our empirical results show that the revised model has improved uncertainty measures, and its performance is competitive to the state-of-the-art methods. 

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3. Training OOD Detectors in their Natural Habitats

   Katz-Samuels, Julian; Nakhleh, Julia; Nowak, Robert; Li, Yixuan (January 2022, International Conference on Machine Learning)

   Out-of-distribution (OOD) detection is important for machine learning models deployed in the wild. Recent methods use auxiliary outlier data to regularize the model for improved OOD detection. However, these approaches make a strong distributional assumption that the auxiliary outlier data is completely separable from the in-distribution (ID) data. In this paper, we propose a novel framework that leverages wild mixture data -- that naturally consists of both ID and OOD samples. Such wild data is abundant and arises freely upon deploying a machine learning classifier in their \emph{natural habitats}. Our key idea is to formulate a constrained optimization problem and to show how to tractably solve it. Our learning objective maximizes the OOD detection rate, subject to constraints on the classification error of ID data and on the OOD error rate of ID examples. We extensively evaluate our approach on common OOD detection tasks and demonstrate superior performance. 

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4. Neural-Symbolic Inference for Robust Autoregressive Graph Parsing via Compositional Uncertainty Quantification

   Lin, Zi; Liu, Jeremiah; Shang, Jingbo (January 2022, Proceedings of the 2022 Conference on Empirical Methods in Natural Language Processing)

   Pre-trained seq2seq models excel at graph semantic parsing with rich annotated data, but generalize worse to out-of-distribution (OOD) and long-tail examples. In comparison, symbolic parsers under-perform on population-level metrics, but exhibit unique strength in OOD and tail generalization. In this work, we study compositionality-aware approach to neural-symbolic inference informed by model confidence, performing fine-grained neural-symbolic reasoning at subgraph level (i.e., nodes and edges) and precisely targeting subgraph components with high uncertainty in the neural parser. As a result, the method combines the distinct strength of the neural and symbolic approaches in capturing different aspects of the graph prediction, leading to well-rounded generalization performance both across domains and in the tail. We empirically investigate the approach in the English Resource Grammar (ERG) parsing problem on a diverse suite of standard in-domain and seven OOD corpora. Our approach leads to 35.26% and 35.60% error reduction in aggregated SMATCH score over neural and symbolic approaches respectively, and 14% absolute accuracy gain in key tail linguistic categories over the neural model, outperforming prior state-of-art methods that do not account for compositionality or uncertainty. 

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5. A Transfer Learning with Deep Neural Network Approach for Network Intrusion Detection

   Mohammad Masum, Hossain Shahriar (April 2021, International journal of intellligent computing research)

   Ayahiko Niimi, Future University-Hakodate (Ed.)

   Traditional Network Intrusion Detection Systems (NIDS) encounter difficulties due to the exponential growth of network traffic data and modern attacks' requirements. This paper presents a novel network intrusion classification framework using transfer learning from the VGG-16 pre-trained model. The framework extracts feature leveraging pre-trained weights trained on the ImageNet dataset in the initial step, and finally, applies a deep neural network to the extracted features for intrusion classification. We applied the presented framework on NSL-KDD, a benchmark dataset for network intrusion, to evaluate the proposed framework's performance. We also implemented other pre-trained models such as VGG19, MobileNet, ResNet-50, and Inception V3 to evaluate and compare performance. This paper also displays both binary classification (normal vs. attack) and multi-class classification (classifying types of attacks) for network intrusion detection. The experimental results show that feature extraction using VGG-16 outperforms other pre-trained models producing better accuracy, precision, recall, and false alarm rates. 

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