Search Results for author: Zhi Xu

Found 19 papers, 6 papers with code

HQA-Attack: Toward High Quality Black-Box Hard-Label Adversarial Attack on Text

1 code implementation NeurIPS 2023 Han Liu, Zhi Xu, Xiaotong Zhang, Feng Zhang, Fenglong Ma, Hongyang Chen, Hong Yu, Xianchao Zhang

Black-box hard-label adversarial attack on text is a practical and challenging task, as the text data space is inherently discrete and non-differentiable, and only the predicted label is accessible.

Adversarial Attack Hard-label Attack +5

Contributions of Shape, Texture, and Color in Visual Recognition

1 code implementation19 Jul 2022 Yunhao Ge, Yao Xiao, Zhi Xu, Xingrui Wang, Laurent Itti

We use human experiments to confirm that both HVE and humans predominantly use some specific features to support the classification of specific classes (e. g., texture is the dominant feature to distinguish a zebra from other quadrupeds, both for humans and HVE).

Attribute General Classification +2

Encouraging Disentangled and Convex Representation with Controllable Interpolation Regularization

no code implementations6 Dec 2021 Yunhao Ge, Zhi Xu, Yao Xiao, Gan Xin, Yunkui Pang, Laurent Itti

(2) They lack convexity constraints, which is important for meaningfully manipulating specific attributes for downstream tasks.

Data Augmentation Disentanglement +2

Towards Generic Interface for Human-Neural Network Knowledge Exchange

no code implementations29 Sep 2021 Yunhao Ge, Yao Xiao, Zhi Xu, Linwei Li, Ziyan Wu, Laurent Itti

Take image classification as an example, HNI visualizes the reasoning logic of a NN with class-specific Structural Concept Graphs (c-SCG), which are human-interpretable.

Image Classification Zero-Shot Learning

PerSim: Data-Efficient Offline Reinforcement Learning with Heterogeneous Agents via Personalized Simulators

no code implementations NeurIPS 2021 Anish Agarwal, Abdullah Alomar, Varkey Alumootil, Devavrat Shah, Dennis Shen, Zhi Xu, Cindy Yang

We consider offline reinforcement learning (RL) with heterogeneous agents under severe data scarcity, i. e., we only observe a single historical trajectory for every agent under an unknown, potentially sub-optimal policy.

Offline RL reinforcement-learning +1

Generative Auto-Encoder: Non-adversarial Controllable Synthesis with Disentangled Exploration

no code implementations1 Jan 2021 Yunhao Ge, Gan Xin, Zhi Xu, Yao Xiao, Yunkui Pang, Yining HE, Laurent Itti

DEAE can become a generative model and synthesis semantic controllable samples by interpolating latent code, which can even synthesis novel attribute value never is shown in the original dataset.

Attribute Data Augmentation +2

Rethinking the Value of Labels for Improving Class-Imbalanced Learning

1 code implementation NeurIPS 2020 Yuzhe Yang, Zhi Xu

Real-world data often exhibits long-tailed distributions with heavy class imbalance, posing great challenges for deep recognition models.

Long-tail Learning

Sample Efficient Reinforcement Learning via Low-Rank Matrix Estimation

no code implementations NeurIPS 2020 Devavrat Shah, Dogyoon Song, Zhi Xu, Yuzhe Yang

As our key contribution, we develop a simple, iterative learning algorithm that finds $\epsilon$-optimal $Q$-function with sample complexity of $\widetilde{O}(\frac{1}{\epsilon^{\max(d_1, d_2)+2}})$ when the optimal $Q$-function has low rank $r$ and the discounting factor $\gamma$ is below a certain threshold.

Learning Theory reinforcement-learning +1

Stable Reinforcement Learning with Unbounded State Space

no code implementations L4DC 2020 Devavrat Shah, Qiaomin Xie, Zhi Xu

As a proof of concept, we propose an RL policy using Sparse-Sampling-based Monte Carlo Oracle and argue that it satisfies the stability property as long as the system dynamics under the optimal policy respects a Lyapunov function.

reinforcement-learning Reinforcement Learning (RL) +1

On Reinforcement Learning for Turn-based Zero-sum Markov Games

no code implementations25 Feb 2020 Devavrat Shah, Varun Somani, Qiaomin Xie, Zhi Xu

For a concrete instance of EIS where random policy is used for "exploration", Monte-Carlo Tree Search is used for "policy improvement" and Nearest Neighbors is used for "supervised learning", we establish that this method finds an $\varepsilon$-approximate value function of Nash equilibrium in $\widetilde{O}(\varepsilon^{-(d+4)})$ steps when the underlying state-space of the game is continuous and $d$-dimensional.

reinforcement-learning Reinforcement Learning (RL)

Harnessing Structures for Value-Based Planning and Reinforcement Learning

1 code implementation ICLR 2020 Yuzhe Yang, Guo Zhang, Zhi Xu, Dina Katabi

In this paper, we propose to exploit the underlying structures of the state-action value function, i. e., Q function, for both planning and deep RL.

Atari Games reinforcement-learning +1

ME-Net: Towards Effective Adversarial Robustness with Matrix Estimation

1 code implementation28 May 2019 Yuzhe Yang, Guo Zhang, Dina Katabi, Zhi Xu

We show that this process destroys the adversarial structure of the noise, while re-enforcing the global structure in the original image.

Adversarial Robustness

Understanding & Generalizing AlphaGo Zero

no code implementations ICLR 2019 Ravichandra Addanki, Mohammad Alizadeh, Shaileshh Bojja Venkatakrishnan, Devavrat Shah, Qiaomin Xie, Zhi Xu

AlphaGo Zero (AGZ) introduced a new {\em tabula rasa} reinforcement learning algorithm that has achieved superhuman performance in the games of Go, Chess, and Shogi with no prior knowledge other than the rules of the game.

Decision Making reinforcement-learning +2

Non-Asymptotic Analysis of Monte Carlo Tree Search

no code implementations14 Feb 2019 Devavrat Shah, Qiaomin Xie, Zhi Xu

In effect, we establish that to learn an $\varepsilon$ approximation of the value function with respect to $\ell_\infty$ norm, MCTS combined with nearest neighbor requires a sample size scaling as $\widetilde{O}\big(\varepsilon^{-(d+4)}\big)$, where $d$ is the dimension of the state space.

Private Sequential Learning

no code implementations6 May 2018 John N. Tsitsiklis, Kuang Xu, Zhi Xu

We formulate a private learning model to study an intrinsic tradeoff between privacy and query complexity in sequential learning.

Robust GANs against Dishonest Adversaries

no code implementations27 Feb 2018 Zhi Xu, Chengtao Li, Stefanie Jegelka

We explore a notion of robustness for generative adversarial models that is pertinent to their internal interactive structure, and show that, perhaps surprisingly, the GAN in its original form is not robust.

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