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Stochastic and Adversarial Online Learning without Hyperparameters

Neural Information Processing Systems

Most online optimization algorithms focus on one of two things: performing well in adversarial settings by adapting to unknown data parameters (such as Lipschitz constants), typically achieving O( T) regret, or performing well in stochastic settings where they can leverage some structure in the losses (such as strong convexity), typically achieving O(log(T)) regret. Algorithms that focus on the former problem hitherto achieved O( T) in the stochastic setting rather than O(log(T)).


Convergent Block Coordinate Descent for Training Tikhonov Regularized Deep Neural Networks

Neural Information Processing Systems

By lifting the ReLU function into a higher dimensional space, we develop a smooth multi-convex formulation for training feed-forward deep neural networks (DNNs). This allows us to develop a block coordinate descent (BCD) training algorithm consisting of a sequence of numerically well-behaved convex optimizations. Using ideas from proximal point methods in convex analysis, we prove that this BCD algorithm will converge globally to a stationary point with R-linear convergence rate of order one. In experiments with the MNIST database, DNNs trained with this BCD algorithm consistently yielded better test-set error rates than identical DNN architectures trained via all the stochastic gradient descent (SGD) variants in the Caffe toolbox.


Multi-Agent Actor-Critic for Mixed Cooperative-Competitive Environments

Neural Information Processing Systems

We explore deep reinforcement learning methods for multi-agent domains. We begin by analyzing the difficulty of traditional algorithms in the multi-agent case: Q-learning is challenged by an inherent non-stationarity of the environment, while policy gradient suffers from a variance that increases as the number of agents grows. We then present an adaptation of actor-critic methods that considers action policies of other agents and is able to successfully learn policies that require complex multiagent coordination. Additionally, we introduce a training regimen utilizing an ensemble of policies for each agent that leads to more robust multi-agent policies. We show the strength of our approach compared to existing methods in cooperative as well as competitive scenarios, where agent populations are able to discover various physical and informational coordination strategies.


Mean teachers are better role models: Weight-averaged consistency targets improve semi-supervised deep learning results

Neural Information Processing Systems

The recently proposed Temporal Ensembling has achieved state-of-the-art results in several semi-supervised learning benchmarks. It maintains an exponential moving average of label predictions on each training example, and penalizes predictions that are inconsistent with this target. However, because the targets change only once per epoch, Temporal Ensembling becomes unwieldy when learning large datasets. To overcome this problem, we propose Mean Teacher, a method that averages model weights instead of label predictions. As an additional benefit, Mean Teacher improves test accuracy and enables training with fewer labels than Temporal Ensembling. Without changing the network architecture, Mean Teacher achieves an error rate of 4.35% on SVHN with 250 labels, outperforming Temporal Ensembling trained with 1000 labels. We also show that a good network architecture is crucial to performance. Combining Mean Teacher and Residual Networks, we improve the state of the art on CIFAR-10 with 4000 labels from 10.55% to 6.28%, and on ImageNet 2012 with 10% of the labels from 35.24% to 9.11%.


Using Options and Covariance Testing for Long Horizon Off-Policy Policy Evaluation

Neural Information Processing Systems

Evaluating a policy by deploying it in the real world can be risky and costly. Off-policy policy evaluation (OPE) algorithms use historical data collected from running a previous policy to evaluate a new policy, which provides a means for evaluating a policy without requiring it to ever be deployed. Importance sampling is a popular OPE method because it is robust to partial observability and works with continuous states and actions. However, the amount of historical data required by importance sampling can scale exponentially with the horizon of the problem: the number of sequential decisions that are made. We propose using policies over temporally extended actions, called options, and show that combining these policies with importance sampling can significantly improve performance for long-horizon problems. In addition, we can take advantage of special cases that arise due to options-based policies to further improve the performance of importance sampling. We further generalize these special cases to a general covariance testing rule that can be used to decide which weights to drop in an IS estimate, and derive a new IS algorithm called Incremental Importance Sampling that can provide significantly more accurate estimates for a broad class of domains.


New laws close gap in California on deepfake child pornography

Los Angeles Times

Using an AI-powered app to create fake nude pictures of people without their consent violates all sorts of norms, especially when those people are minors. It would not, however, violate California law -- yet. A pair of bills newly signed by Gov. Gavin Newsom outlaw the creation, possession and distribution of sexually charged images of minors even when they're created with computers, not cameras. The measures take effect Jan. 1. The expansion of state prohibitions comes as students are increasingly being victimized by apps that use artificial intelligence either to take a photo of a fully clothed real person and digitally generate a nude body ("undresser" apps) or seamlessly superimpose the image of a person's face onto a nude body from a pornographic video.


What Kind of Writer Is ChatGPT?

The New Yorker

Last spring, a graduate student in social anthropology--let's call him Chris--sat down at his laptop and asked ChatGPT for help with a writing assignment. He pasted a few thousand words, a mix of rough summaries and jotted-down bullet points, into the text box that serves as ChatGPT's interface. "Here's my entire exam," he wrote. "Don't edit it, I will tell you what to do after you've read it." Chris was tackling a difficult paper about perspectivism, which is the anthropological principle that one's perspective inevitably shapes the observations one makes and the knowledge one acquires.


A General Framework for Robust Interactive Learning

Neural Information Processing Systems

We propose a general framework for interactively learning models, such as (binary or non-binary) classifiers, orderings/rankings of items, or clusterings of data points. Our framework is based on a generalization of Angluin's equivalence query model and Littlestone's online learning model: in each iteration, the algorithm proposes a model, and the user either accepts it or reveals a specific mistake in the proposal.