Enforcing complex (e.g., nonconvex) operational constraints is a critical challenge in real-world learning and control systems. However, existing methods struggle to efficiently enforce general classes of constraints. To address this, we propose a novel data-driven amortized approach that uses a trained autoencoder as an approximate projector to provide fast corrections to infeasible predictions. Specifically, we train an autoencoder using an adversarial objective to learn a structured, convex latent representation of the feasible set. This enables rapid correction of neural network outputs by projecting their associated latent representations onto a simple convex shape before decoding into the original feasible set. We test our approach on a diverse suite of constrained optimization and reinforcement learning problems with challenging nonconvex constraints. Results show that our method effectively enforces constraints at a low computational cost, offering a practical alternative to expensive feasibility correction techniques based on traditional solvers.
Carnegie Mellon University（卡内基梅隆大学）；University of Colorado, Boulder（科罗拉多大学博尔德分校）
While reinforcement learning (RL) is gaining popularity in energy systems control, its real-world applications are limited due to the fact that the actions from learned policies may not satisfy functional requirements or be feasible for the underlying physical system. In this work, we propose PROjected Feasibility (PROF), a method to enforce convex operational constraints within neural policies. Specifically, we incorporate a differentiable projection layer within a neural network-based policy to enforce that all learned actions are feasible. We then update the policy end-to-end by propagating…
In this work, we propose a deep reinforcement learning (DRL) model for finding a feasible solution for (mixed) integer programming (MIP) problems. Finding a feasible solution for MIP problems is critical because many successful heuristics rely on a known initial feasible solution. However, it is in general NP-hard. Inspired by the feasibility pump (FP), a well-known heuristic for searching feasible MIP solutions, we develop a smart feasibility pump (SFP) method using DRL. In addition to multi-layer perception (MLP), we propose a novel convolution neural network (CNN) structure for the policy n…
Hard Constraints, Smooth Gradients: Learning Feasible Inventory Policies via Differentiable Projection
TUM School of Management, Technical University of Munich（慕尼黑工业大学TUM管理学院）；Esade, Ramon Llull University（拉蒙·柳利大学ESADE商学院）；Munich Data Science Institute (MDSI), Technical University of Munich（慕尼黑工业大学慕尼黑数据科学研究所）
Power Flow Feasibility Assessment Using Variational Graph Autoencoders
Agència de Gestió d’Ajuts Universitaris i de Recerca (AGAUR)（加泰罗尼亚大学与研究资助管理局（AGAUR））；Departament de Recerca i Universitats of the Generalitat de Catalunya（加泰罗尼亚自治区研究与大学部）
Near-Linear Time Projection onto the $\ell_{1,\infty}$ Ball; Application to Sparse Autoencoders
Université Côte d’Azur（蔚蓝海岸大学）；CNRS（法国国家科学研究中心）；King Abdullah University of Science and Technology (KAUST)（阿卜杜拉国王科技大学）；SDAIA-KAUST AI（SDAIA-KAUST人工智能中心）
An Empirical Study on Improving SimCLR's Nonlinear Projection Head using Pretrained Autoencoder Embeddings
Faculty of Engineering（工程学院）；Computer Science Osnabrück University of Applied Sciences（计算机科学奥斯纳布吕克应用科学大学）；Semantic Information Systems Group Osnabrück University（奥斯纳布吕克大学语义信息系统组）；German Research Center for AI (DFKI)（德国人工智能研究中心（DFKI））
Autoencoder (AE) is a neural network (NN) architecture that is trained to reconstruct an input at its output. By measuring the reconstruction errors of new input samples, AE can detect anomalous samples deviated from the trained data distribution. The key to success is to achieve high-fidelity reconstruction (HFR) while restricting AE's capability of generalization beyond training data, which should be balanced commonly via iterative re-training. Alternatively, we propose a novel framework of AE-based anomaly detection, coined HFR-AE, by projecting new inputs into a subspace wherein the traine…
University of Aberdeen（阿伯丁大学）；University of Sheffield（谢菲尔德大学）；University of Surrey（萨里大学）
We tackle the problem disentangling the latent space of an autoencoder in order to separate labelled attribute information from other characteristic information. This then allows us to change selected attributes while preserving other information. Our method, matrix subspace projection, is much simpler than previous approaches to latent space factorisation, for example not requiring multiple discriminators or a careful weighting among their loss functions. Furthermore our new model can be applied to autoencoders as a plugin, and works across diverse domains such as images or text. We demonstra…
Compressed sensing techniques enable efficient acquisition and recovery of sparse, high-dimensional data signals via low-dimensional projections. In this work, we propose Uncertainty Autoencoders, a learning framework for unsupervised representation learning inspired by compressed sensing. We treat the low-dimensional projections as noisy latent representations of an autoencoder and directly learn both the acquisition (i.e., encoding) and amortized recovery (i.e., decoding) procedures. Our learning objective optimizes for a tractable variational lower bound to the mutual information between th…
Consider convex optimization problems subject to a large number of constraints. We focus on stochastic problems in which the objective takes the form of expected values and the feasible set is the intersection of a large number of convex sets. We propose a class of algorithms that perform both stochastic gradient descent and random feasibility updates simultaneously. At every iteration, the algorithms sample a number of projection points onto a randomly selected small subsets of all constraints. Three feasibility update schemes are considered: averaging over random projected points, projecting…
In the construction of reduced-order models for dynamical systems, linear projection methods, such as proper orthogonal decompositions, are commonly employed. However, for many dynamical systems, the lower dimensional representation of the state space can most accurately be described by a \textit{nonlinear} manifold. Previous research has shown that deep learning can provide an efficient method for performing nonlinear dimension reduction, though they are dependent on the availability of training data and are often problem-specific \citep[see][]{carlberg_ca}. Here, we utilize randomized traini…
We study video-specific autoencoders that allow a human user to explore, edit, and efficiently transmit videos. Prior work has independently looked at these problems (and sub-problems) and proposed different formulations. In this work, we train a simple autoencoder (from scratch) on multiple frames of a specific video. We observe: (1) latent codes learned by a video-specific autoencoder capture spatial and temporal properties of that video; and (2) autoencoders can project out-of-sample inputs onto the video-specific manifold. These two properties allow us to explore, edit, and efficiently tra…
Virtual Big Data (VBD) proved to be effective to alleviate mode collapse and vanishing generator gradient as two major problems of Generative Adversarial Neural Networks (GANs) very recently. In this paper, we investigate the capability of VBD to address two other major challenges in Machine Learning including deep autoencoder training and imbalanced data classification. First, we prove that, VBD can significantly decrease the validation loss of autoencoders via providing them a huge diversified training data which is the key to reach better generalization to minimize the over-fitting problem.…
Learning to Optimize for Mixed-Integer Non-linear Programming with Feasibility Guarantees
Department of Mechanical and Industrial Engineering（机械与工业工程系）；University of Toronto（多伦多大学）；Department of Civil and Systems Engineering（土木与系统工程系）；The Ralph O’Connor Sustainable Energy Institute (ROSEI)（拉尔夫·奥康纳可持续能源研究所）；Data Science and AI Institute (DSAI)（数据科学与人工智能研究所）；Johns Hopkins University（约翰霍普金斯大学）
Sichuan University（四川大学）；University of Electronic Science and Technology of China（电子科技大学）；University of Adelaide（阿德莱德大学）
Weakly-supervised anomaly detection aims at learning an anomaly detector from a limited amount of labeled data and abundant unlabeled data. Recent works build deep neural networks for anomaly detection by discriminatively mapping the normal samples and abnormal samples to different regions in the feature space or fitting different distributions. However, due to the limited number of annotated anomaly samples, directly training networks with the discriminative loss may not be sufficient. To overcome this issue, this paper proposes a novel strategy to transform the input data into a more meaning…
Visa Research（Visa研究院）；Michigan State University（密歇根州立大学）
Deep learning-based systems have been shown to be vulnerable to adversarial attacks in both digital and physical domains. While feasible, digital attacks have limited applicability in attacking deployed systems, including face recognition systems, where an adversary typically has access to the input and not the transmission channel. In such setting, physical attacks that directly provide a malicious input through the input channel pose a bigger threat. We investigate the feasibility of conducting real-time physical attacks on face recognition systems using adversarial light projections. A setu…
Several regularization methods have recently been introduced which force the latent activations of an autoencoder or deep neural network to conform to either a Gaussian or hyperspherical distribution, or to minimize the implicit rank of the distribution in latent space. In the present work, we introduce a novel regularizing loss function which simulates a pairwise repulsive force between items and an attractive force of each item toward the origin. We show that minimizing this loss function in isolation achieves a hyperspherical distribution. Moreover, when used as a regularizing term, the sca…
Deep Invertible Autoencoders for Dimensionality Reduction of Dynamical Systems
MOX Laboratory, Department of Mathematics, Politecnico di Milano（米兰理工学院数学系MOX实验室）；Department of Applied Mathematics, University of Twente（埃因霍温理工大学应用数学系）
UiT–The Arctic University of Norway（挪威北极大学）；University of Exeter（埃克塞特大学）
In this paper we introduce the deep kernelized autoencoder, a neural network model that allows an explicit approximation of (i) the mapping from an input space to an arbitrary, user-specified kernel space and (ii) the back-projection from such a kernel space to input space. The proposed method is based on traditional autoencoders and is trained through a new unsupervised loss function. During training, we optimize both the reconstruction accuracy of input samples and the alignment between a kernel matrix given as prior and the inner products of the hidden representations computed by the autoen…
University of Illinois at Urbana-Champaign（伊利诺伊大学厄巴纳-香槟分校）
Model reduction of high-dimensional dynamical systems alleviates computational burdens faced in various tasks from design optimization to model predictive control. One popular model reduction approach is based on projecting the governing equations onto a subspace spanned by basis functions obtained from the compression of a dataset of solution snapshots. However, this method is intrusive since the projection requires access to the system operators. Further, some systems may require special treatment of nonlinearities to ensure computational efficiency or additional modeling to preserve stabili…
Aarhus University（奥胡斯大学）；Technical University of Denmark（丹麦技术大学）
The encoder network of an autoencoder is an approximation of the nearest point projection onto the manifold spanned by the decoder. A concern with this approximation is that, while the output of the encoder is always unique, the projection can possibly have infinitely many values. This implies that the latent representations learned by the autoencoder can be misleading. Borrowing from geometric measure theory, we introduce the idea of using the reach of the manifold spanned by the decoder to determine if an optimal encoder exists for a given dataset and decoder. We develop a local generalizati…
Generative AutoEncoders require a chosen probability distribution in latent space, usually multivariate Gaussian. The original Variational AutoEncoder (VAE) uses randomness in encoder - causing problematic distortion, and overlaps in latent space for distinct inputs. It turned out unnecessary: we can instead use deterministic encoder with additional regularizer to ensure that sample distribution in latent space is close to the required. The original approach (WAE) uses Wasserstein metric, what required comparing with random sample and using an arbitrarily chosen kernel. Later CWAE finally deri…
In the last few years there have been important advancements in generative models with the two dominant approaches being Generative Adversarial Networks (GANs) and Variational Autoencoders (VAEs). However, standard Autoencoders (AEs) and closely related structures have remained popular because they are easy to train and adapt to different tasks. An interesting question is if we can achieve state-of-the-art performance with AEs while retaining their good properties. We propose an answer to this question by introducing a new model called Y-Autoencoder (Y-AE). The structure and training procedure…
3D Masked Autoencoders are Robust Learners of Volumetric and Multimodal Cellular Representations for Microscopy
Institute of AI for Health & Helmholtz AI, Computational Health Center, Helmholtz Munich – German Research Center for Environmental Health（亥姆霍兹慕尼黑中心 - 德国环境健康研究中心，计算健康中心，健康人工智能研究所与亥姆霍兹人工智能）；Department of Medicine III, Ludwig-Maximilian-University Hospital（路德维希-马克西米利安大学医院第三内科）；Department of Physics, Ludwig-Maximilian-University（路德维希-马克西米利安大学物理系）；German Cancer Consortium (DKTK), partner site Munich（德国癌症联盟（DKTK）慕尼黑合作站点）；Munich Center for Machine Learning (MCML)（慕尼黑机器学习中心（MCML））
Differentiable Projection-based Learn to Optimize in Wireless Network-Part I: Convex Constrained (Non-)Convex Programming
State Key Laboratory of ISN（ISN国家重点实验室）；School of Telecommunications Engineering, Xidian University（西安电子科技大学通信工程学院）；School of Cyber Engineering, Xidian University（西安电子科技大学网络与信息安全学院）
Negative Binomial Variational Autoencoders for Overdispersed Latent Modeling
Southeast University（东南大学）；China Medical University Shenyang（中国医科大学沈阳）；University of Chinese Academy of Science（中国科学院大学）；Alibaba Cloud（阿里云）；Center for Applied Statistics and School of Statistics, Renmin University of China（中国人民大学应用统计中心与统计学院）
DIRESA, a distance-preserving nonlinear dimension reduction technique based on regularized autoencoders
Department of Electronics and Informatics, Vrije Universiteit Brussel（比利时布鲁塞尔自由大学电子与信息学院）；Observations Scientific Service, Royal Meteorological Institute（皇家气象研究所观测科学部门）
In representation learning and non-linear dimension reduction, there is a huge interest to learn the 'disentangled' latent variables, where each sub-coordinate almost uniquely controls a facet of the observed data. While many regularization approaches have been proposed on variational autoencoders, heuristic tuning is required to balance between disentanglement and loss in reconstruction accuracy -- due to the unsupervised nature, there is no principled way to find an optimal weight for regularization. Motivated to completely bypass regularization, we consider a projection strategy: modifying …
