GenAI4ELab/papercli-papers huggingface dataset:
Grounding High Dimensional Representation Similarity by Comparing Decodability and Network Performance
Authors: Lucas Hayne; Heejung Jung; Abhijit Suresh; R. McKell Carter
Venue: ICLR 2023 (Submitted to ICLR 2023)

Abstract: To understand and interpret neural networks, representation similarity metrics have been used to compare learned representations between and across networks. Recent experiments have compared these similarity metrics to find the best performing and the most robust metrics, noting that classic baselines perform surprisingly well. These experiments are mostly constrained to studying relatively low-dimensional representations because of the computational cost of prominent representation similarity metrics. We extend previous work to test representation similarity metrics on larger convolutional networks processing larger images. In order to make this work possible, we employ reformulated representation similarity metrics for use on very high-dimensional representations. Using these reformulated similarity metrics, we test how well each metric captures changes to representations induced by ablations in two popular convolutional networks. In order to ground the effects of changes to representations in function, we use linear decoding probes and network performance measures. These measures of function allow us to test how well similarity metrics capture changes in decodable information versus changes in network performance. Linear decoding methods index available information in the representation, while network performance measures index the information used by the network. We show that all the tested representation similarity metrics significantly predict changes in network function and decodability. Within these metrics, on average, Procrustes and CKA outperform regularized CCA-based methods. All metrics predict decodability changes significantly better than they do network function. Procrustes and CKA do not outperform regularized CCA-based metrics for all network and functionality measure combinations. We add to the growing literature on representational similarity metrics to facilitate the improvement of current metrics for network interpretability.
Generalized Belief Transport
Authors: Junqi Wang; PEI WANG; Patrick Shafto
Venue: ICLR 2023 (Submitted to ICLR 2023)

Abstract: Human learners have ability to adopt appropriate learning approaches depending on constraints such as prior on the hypothesis and urgency of decision. However, existing learning models are typically considered individually rather than in relation to one and other. To build agents that have the ability to move between different modes of learning over time, it is important to understand how learning models are related as points in a broader space of possibilities. We introduce a mathematical framework, Generalized Belief Transport (GBT), that unifies and generalizes prior models, including Bayesian inference, cooperative communication and classification, as parameterizations of three learning constraints within Unbalanced Optimal Transport (UOT). We visualize the space of learning models encoded by GBT as a cube which includes classic learning models as special points. We derive critical properties of this parameterized space including proving continuity and differentiability which is the basis for model interpolation, and study limiting behavior of the parameters, which allows attaching learning models on the boundaries. Moreover, we investigate the long-run behavior of GBT, explore convergence properties of models in GBT mathematical and computationally, and formulate conjectures about general behavior. We conclude with open questions and implications for more unified models of learning.
Boosting Out-of-Distribution Detection with Multiple Pre-trained Models 
Authors: Feng Xue; Zi He; Chuanlong Xie; Falong Tan; Zhenguo Li
Venue: ICLR 2023 (Submitted to ICLR 2023)

Abstract: Out-of-Distribution (OOD) detection, i.e., identifying whether an input is sampled from a novel distribution other than the training distribution, is a critical task for safely deploying machine learning systems in the open world. Recently, post hoc detection utilizing pre-trained models has shown promising performance and can be scaled to large-scale problems. This advance raises a natural question: Can we leverage the diversity of multiple pre-trained models to improve the performance of post hoc detection methods? In this work, we propose a detection enhancement method by ensembling multiple detection decisions derived from a zoo of pre-trained models. Our approach uses the p-value instead of the commonly used hard threshold and leverages a fundamental framework of multiple hypothesis testing to control the true positive rate for In-Distribution (ID) data. We focus on the usage of model zoos and provide systematic empirical comparisons with current state-of-the-art methods on various OOD detection benchmarks. The proposed ensemble scheme shows consistent improvement compared to single-model detectors and significantly outperforms the current competitive methods. Our method substantially improves the relative performance by $65.40\%$ and $26.96\%$ on the CIFAR10 and ImageNet benchmarks.
Private GANs, Revisited
Authors: Alex Bie; Gautam Kamath; Guojun Zhang
Venue: ICLR 2023 (Submitted to ICLR 2023)

Abstract: We show that with improved training, the standard approach for differentially private GANs -- updating the discriminator with noisy gradients -- achieves or competes with state-of-the-art results for private image synthesis. Existing instantiations of this approach neglect to consider how adding noise only to discriminator updates disrupts the careful balance between generator and discriminator necessary for successful GAN training. We show that a simple fix restores parity: taking more discriminator steps between generator steps. Finally, with the goal of restoring parity between generator and discriminator, we experiment with further modifications to improve discriminator training and see further improvements. For MNIST at $\eps=10$, our private GANs improve the record FID from 48.4 to 13.0, as well as downstream classifier accuracy from 83.2\% to 95.0\%.
Distribution Aware Metrics for Conditional Natural Language Generation
Authors: David Chan; Yiming Ni; Sudheendra Vijayanarasimhan; David A Ross; Austin Myers; John Canny
Venue: ICLR 2023 (Submitted to ICLR 2023)

Abstract: Traditional automated metrics for evaluating conditional natural language generation use pairwise comparisons between a single generated text and the best-matching gold-standard ground truth text. When multiple ground truths are available, scores are aggregated using an average or max operation across references. While this approach works well when diversity in the ground truth data (i.e. dispersion of the distribution of conditional texts) can be ascribed to noise, such as in automated speech recognition, it does not allow for robust evaluation in the case where diversity in the ground truths represents signal for the model. In this work we argue that existing metrics are not appropriate for domains such as visual description or summarization where ground truths are semantically diverse, and where the diversity in those captions captures useful additional information about the context. We propose a novel paradigm for multi-candidate evaluation of conditional language generation models, and a new family of metrics that compare the {\em distributions} of reference and model-generated caption sets using small sample sets of each.  We demonstrate the utility of our approach with a case study in visual description: where we show that existing models optimize for single-description quality over diversity, and gain some insights into how sampling methods and temperature impact description quality and diversity.
Unveiling The Mask of Position-Information Pattern Through the Mist of Image Features
Authors: Chieh Hubert Lin; Hung-Yu Tseng; Hsin-Ying Lee; Maneesh Kumar Singh; Ming-Hsuan Yang
Venue: ICLR 2023 (Submitted to ICLR 2023)

Abstract: Recent studies have shown that paddings in convolutional neural networks encode absolute position information which can negatively affect the model performance for certain tasks. However, existing metrics for quantifying the strength of positional information remain unreliable and frequently lead to erroneous results. To address this issue, we propose novel metrics for measuring and visualizing the encoded positional information. We formally define the encoded information as Position-information Pattern from Padding (PPP) and conduct a series of experiments to study its properties as well as its formation. The proposed metrics measure the presence of positional information more reliably than the existing metrics based on PosENet and tests in F-Conv. We also demonstrate that for any extant (and proposed) padding schemes, PPP is primarily a learning artifact and is less dependent on the characteristics of the underlying padding schemes.
FedCL: Critical Learning Periods-aware Adaptive Client Selection in Federated Learning
Authors: Gang Yan; Hao Wang; Xu Yuan; Jian Li
Venue: ICLR 2023 (Submitted to ICLR 2023)

Abstract: Federated learning (FL) is a distributed optimization paradigm that learns from data samples distributed across a number of clients.  Adaptive client selection that is cognizant of the training progress of clients has become a major trend to improve FL efficiency but not yet well-understood.   Most existing FL methods such as FedAvg and its state-of-the-art variants implicitly assume that all learning phases during the FL training process are equally important.  Unfortunately, this assumption has been revealed to be invalid due to recent findings on critical learning (CL) periods, in which small gradient errors may lead to an irrecoverable deficiency on final test accuracy.  In this paper, we develop FedCL, a CL periods-aware FL framework to reveal that adaptively augmenting exiting FL methods with CL periods, the resultant performance is significantly improved when the client selection is guided by the discovered CL periods.  Experiments based on various machine learning models and datasets validate that the proposed FedCL framework consistently achieves an improved model accuracy while maintains comparable or even better communication efficiency as compared to state-of-the-art methods, demonstrating a promising and easily adopted method for tackling the heterogeneity of FL training.
Iterative Patch Selection for High-Resolution Image Recognition
Authors: Benjamin Bergner; Christoph Lippert; Aravindh Mahendran
Venue: ICLR 2023 (ICLR 2023 poster)

Abstract: High-resolution images are prevalent in various applications, such as autonomous driving and computer-aided diagnosis. However, training neural networks on such images is computationally challenging and easily leads to out-of-memory errors even on modern GPUs. We propose a simple method, Iterative Patch Selection (IPS), which decouples the memory usage from the input size and thus enables the processing of arbitrarily large images under tight hardware constraints. IPS achieves this by selecting only the most salient patches, which are then aggregated into a global representation for image recognition. For both patch selection and aggregation, a cross-attention based transformer is introduced, which exhibits a close connection to Multiple Instance Learning. Our method demonstrates strong performance and has wide applicability across different domains, training regimes and image sizes while using minimal accelerator memory. For example, we are able to finetune our model on whole-slide images consisting of up to 250k patches (>16 gigapixels) with only 5 GB of GPU VRAM at a batch size of 16.
Loss Landscapes are All You Need: Neural Network Generalization Can Be Explained Without the Implicit Bias of Gradient Descent
Authors: Ping-yeh Chiang; Renkun Ni; David Yu Miller; Arpit Bansal; Jonas Geiping; Micah Goldblum; Tom Goldstein
Venue: ICLR 2023 (ICLR 2023 notable top 25%)

Abstract: It is commonly believed that the implicit regularization of optimizers is needed for neural networks to generalize in the overparameterized regime. In this paper, we observe experimentally that this implicit regularization behavior is {\em generic}, i.e. it does not depend strongly on the choice of optimizer. We demonstrate this by training neural networks using several gradient-free optimizers, which do not benefit from properties that are often attributed to gradient-based optimizers.   This includes a guess-and-check optimizer that generates uniformly random parameter vectors until finding one that happens to achieve perfect train accuracy, and a zeroth-order Pattern Search optimizer that uses no gradient computations. In the low sample and few-shot regimes, where zeroth order optimizers are most computationally tractable, we find that these non-gradient optimizers achieve test accuracy comparable to SGD. The code to reproduce results can be found at https://github.com/Ping-C/optimizer .
Does Deep Learning Learn to Abstract? A Systematic Probing Framework
Authors: Shengnan An; Zeqi Lin; Bei Chen; Qiang Fu; Nanning Zheng; Jian-Guang Lou
Venue: ICLR 2023 (ICLR 2023 poster)

Abstract: Abstraction is a desirable capability for deep learning models, which means to induce abstract concepts from concrete instances and flexibly apply them beyond the learning context. At the same time, there is a lack of clear understanding about both the presence and further characteristics of this capability in deep learning models. In this paper, we introduce a systematic probing framework to explore the abstraction capability of deep learning models from a transferability perspective. A set of controlled experiments are conducted based on this framework, providing strong evidence that two probed pre-trained language models (PLMs), T5 and GPT2, have the abstraction capability. We also conduct in-depth analysis, thus shedding further light: (1) the whole training phase exhibits a "memorize-then-abstract" two-stage process; (2) the learned abstract concepts are gathered in a few middle-layer attention heads, rather than being evenly distributed throughout the model; (3) the probed abstraction capabilities exhibit robustness against concept mutations, and are more robust to low-level/source-side mutations than high-level/target-side ones; (4) generic pre-training is critical to the emergence of abstraction capability, and PLMs exhibit better abstraction with larger model sizes and data scales.
MaskViT: Masked Visual Pre-Training for Video Prediction
Authors: Agrim Gupta; Stephen Tian; Yunzhi Zhang; Jiajun Wu; Roberto Martín-Martín; Li Fei-Fei
Venue: ICLR 2023 (ICLR 2023 poster)

Abstract: The ability to predict future visual observations conditioned on past observations and motor commands can enable embodied agents to plan solutions to a variety of tasks in complex environments. This work shows that we can create good video prediction models by pre-training transformers via masked visual modeling. Our approach, named MaskViT, is based on two simple design decisions. First, for memory and training efficiency, we use two types of window attention: spatial and spatiotemporal. Second, during training, we mask a variable percentage of tokens instead of a fixed mask ratio. For inference, MaskViT generates all tokens via iterative refinement where we incrementally decrease the masking ratio following a mask scheduling function. On several datasets we demonstrate that MaskViT outperforms prior works in video prediction, is parameter efficient, and can generate high resolution videos ($256 \times $256). Further, we demonstrate the benefits of inference speedup (up to $512 \times$) due to iterative decoding by using MaskViT for planning on a real robot. Our work suggests that we can endow embodied agents with powerful predictive models by leveraging the general framework of masked visual modeling with minimal domain knowledge.
CADet: Fully Self-Supervised Anomaly Detection With Contrastive Learning
Authors: Charles Guille-Escuret; Pau Rodriguez; David Vazquez; Ioannis Mitliagkas; Joao Monteiro
Venue: ICLR 2023 (Submitted to ICLR 2023)

Abstract: Handling out-of-distribution (OOD) samples has become a major stake in the real-world deployment of machine learning systems. This work explores the application of self-supervised contrastive learning to the simultaneous detection of two types of OOD samples: unseen classes and adversarial perturbations. Since in practice the distribution of such samples is not known in advance, we do not assume access to OOD examples. We show that similarity functions trained with contrastive learning can be leveraged with the maximum mean discrepancy (MMD) two-sample test to verify whether two independent sets of samples are drawn from the same distribution. Inspired by this approach, we introduce CADet (Contrastive Anomaly Detection), a method based on image augmentations to perform anomaly detection on single samples. CADet compares favorably to adversarial detection methods to detect adversarially perturbed samples on ImageNet. Simultaneously, it achieves comparable performance to unseen label detection methods on two challenging benchmarks: ImageNet-O and iNaturalist. Additionally, CADet is fully self-supervised and requires neither labels for in-distribution samples nor access to out-of-distribution examples.
Reinforcement Learning for Bandits with Continuous Actions and Large Context Spaces
Authors: Paul Duckworth; Bruno Lacerda; Katherine Vallis; Nick Hawes
Venue: ICLR 2023 (Submitted to ICLR 2023)

Abstract: We consider the challenging scenario of contextual bandits with continuous actions and large input ``context'' spaces, e.g. images. We posit that by modifying reinforcement learning (RL) algorithms for continuous control, we can outperform hand-crafted contextual bandit algorithms for continuous actions on standard benchmark datasets, i.e. vector contexts. We demonstrate that parametric policy networks outperform recently published tree-based policies in both average regret and costs on held-out samples. Furthermore, in contrast to previous work, we successfully demonstrate that RL algorithms can generalise contextual bandit problems with continuous actions to large context spaces. We obtain state-of-the-art performance using RL and significantly outperform previous methods on image contexts. Lastly, we introduce a new contextual bandits domain with multi-dimensional continuous action space and image context.
Dilated convolution with learnable spacings
Authors: Ismail Khalfaoui Hassani; Thomas Pellegrini; Timothée Masquelier
Venue: ICLR 2023 (ICLR 2023 poster)

Abstract: Recent works indicate that convolutional neural networks (CNN) need large receptive fields (RF) to compete with visual transformers and their attention mechanism. In CNNs, RFs can simply be enlarged by increasing the convolution kernel sizes. Yet the number of trainable parameters, which scales quadratically with the kernel's size in the 2D case, rapidly becomes prohibitive, and the training is notoriously difficult. This paper presents a new method to increase the RF size without increasing the number of parameters. The dilated convolution (DC) has already been proposed for the same purpose. DC can be seen as a convolution with a kernel that contains only a few non-zero elements placed on a regular grid. Here we present a new version of the DC in which the spacings between the non-zero elements, or equivalently their positions, are no longer fixed but learnable via backpropagation thanks to an interpolation technique. We call this method “Dilated Convolution with Learnable Spacings” (DCLS) and generalize it to the n-dimensional convolution case. However, our main focus here will be on the 2D case. We first tried our approach on ResNet50: we drop-in replaced the standard convolutions with DCLS ones, which increased the accuracy of ImageNet1k classification at iso-parameters, but at the expense of the throughput. Next, we used the recent ConvNeXt state-of-the-art convolutional architecture and drop-in replaced the depthwise convolutions with DCLS ones. This not only increased the accuracy of ImageNet1k classification but also of typical downstream and robustness tasks, again at iso-parameters but this time with negligible cost on throughput, as ConvNeXt uses separable convolutions. Conversely, classic DC led to poor performance with both ResNet50 and ConvNeXt. The code of the method is based on PyTorch and available at: https://github.com/K-H-Ismail/Dilated-Convolution-with-Learnable-Spacings-PyTorch.
Synthetic Data Generation of Many-to-Many Datasets via Random Graph Generation
Authors: Kai Xu; Georgi Ganev; Emile Joubert; Rees Davison; Olivier Van Acker; Luke Robinson
Venue: ICLR 2023 (ICLR 2023 poster)

Abstract: Synthetic data generation (SDG) has become a popular approach to release private datasets.
In SDG, a generative model is fitted on the private real data, and samples drawn from the model are released as the protected synthetic data.
While real-world datasets usually consist of multiple tables with potential \emph{many-to-many} relationships (i.e.~\emph{many-to-many datasets}), recent research in SDG mostly focuses on modeling tables \emph{independently} or only considers generating datasets with special cases of many-to-many relationships such as \emph{one-to-many}.
In this paper, we first study challenges of building faithful generative models for many-to-many datasets, identifying limitations of existing methods.
We then present a novel factorization for many-to-many generative models,  which leads to a scalable generation framework by combining recent results from random graph theory and representation learning.
Finally, we extend the framework to establish the notion of $(\epsilon,\delta)$-differential privacy.
Through a real-world dataset, we demonstrate that our method can generate synthetic datasets while preserving information within and across tables better than its closest competitor.
Learning from Labeled Images and Unlabeled Videos for Video Segmentation
Authors: Cristina Mata; Michael S Ryoo
Venue: ICLR 2023 (Submitted to ICLR 2023)

Abstract: Performance on video object segmentation still lags behind that of image segmentation due to a paucity of labeled videos. Annotations are time-consuming and laborious to collect, and may not be feasibly obtained in certain situations. However there is a growing amount of freely available unlabeled video data which has spurred interest in unsupervised video representation learning. In this work we focus on the setting in which there is no/little access to labeled videos for video object segmentation. To this end we leverage large-scale image segmentation datasets and adversarial learning to train 2D/3D networks for video object segmentation. We first motivate the treatment of images and videos as two separate domains by analyzing the performance gap of an image segmentation network trained on images and applied to videos. Through studies using several image and video segmentation datasets, we show how an adversarial loss placed at various locations within the network can make feature representations invariant to these domains and improve the performance when the network has access to only labeled images and unlabeled videos. To prevent the loss of discriminative semantic class information we apply our adversarial loss within clusters of features and show this boosts our method's performance within Transformer-based models.