Chen, Fan
Where do Large Vision-Language Models Look at when Answering Questions?
Xing, Xiaoying, Kuo, Chia-Wen, Fuxin, Li, Niu, Yulei, Chen, Fan, Li, Ming, Wu, Ying, Wen, Longyin, Zhu, Sijie
Large Vision-Language Models (LVLMs) have shown promising performance in vision-language understanding and reasoning tasks. However, their visual understanding behaviors remain underexplored. A fundamental question arises: to what extent do LVLMs rely on visual input, and which image regions contribute to their responses? It is non-trivial to interpret the free-form generation of LVLMs due to their complicated visual architecture (e.g., multiple encoders and multi-resolution) and variable-length outputs. In this paper, we extend existing heatmap visualization methods (e.g., iGOS++) to support LVLMs for open-ended visual question answering. We propose a method to select visually relevant tokens that reflect the relevance between generated answers and input image. Furthermore, we conduct a comprehensive analysis of state-of-the-art LVLMs on benchmarks designed to require visual information to answer. Our findings offer several insights into LVLM behavior, including the relationship between focus region and answer correctness, differences in visual attention across architectures, and the impact of LLM scale on visual understanding. The code and data are available at https://github.com/bytedance/LVLM_Interpretation.
Near-Optimal Private Learning in Linear Contextual Bandits
Chen, Fan, Li, Jiachun, Rakhlin, Alexander, Simchi-Levi, David
We analyze the problem of private learning in generalized linear contextual bandits. Our approach is based on a novel method of re-weighted regression, yielding an efficient algorithm with regret of order $\sqrt{T}+\frac{1}{\alpha}$ and $\sqrt{T}/\alpha$ in the joint and local model of $\alpha$-privacy, respectively. Further, we provide near-optimal private procedures that achieve dimension-independent rates in private linear models and linear contextual bandits. In particular, our results imply that joint privacy is almost "for free" in all the settings we consider, partially addressing the open problem posed by Azize and Basu (2024).
Decision Making in Changing Environments: Robustness, Query-Based Learning, and Differential Privacy
Chen, Fan, Rakhlin, Alexander
We study the problem of interactive decision making in which the underlying environment changes over time subject to given constraints. We propose a framework, which we call \textit{hybrid Decision Making with Structured Observations} (hybrid DMSO), that provides an interpolation between the stochastic and adversarial settings of decision making. Within this framework, we can analyze local differentially private (LDP) decision making, query-based learning (in particular, SQ learning), and robust and smooth decision making under the same umbrella, deriving upper and lower bounds based on variants of the Decision-Estimation Coefficient (DEC). We further establish strong connections between the DEC's behavior, the SQ dimension, local minimax complexity, learnability, and joint differential privacy. To showcase the framework's power, we provide new results for contextual bandits under the LDP constraint.
Assouad, Fano, and Le Cam with Interaction: A Unifying Lower Bound Framework and Characterization for Bandit Learnability
Chen, Fan, Foster, Dylan J., Han, Yanjun, Qian, Jian, Rakhlin, Alexander, Xu, Yunbei
We develop a unifying framework for information-theoretic lower bound in statistical estimation and interactive decision making. Classical lower bound techniques -- such as Fano's method, Le Cam's method, and Assouad's lemma -- are central to the study of minimax risk in statistical estimation, yet are insufficient to provide tight lower bounds for \emph{interactive decision making} algorithms that collect data interactively (e.g., algorithms for bandits and reinforcement learning). Recent work of Foster et al. (2021, 2023) provides minimax lower bounds for interactive decision making using seemingly different analysis techniques from the classical methods. These results -- which are proven using a complexity measure known as the \emph{Decision-Estimation Coefficient} (DEC) -- capture difficulties unique to interactive learning, yet do not recover the tightest known lower bounds for passive estimation. We propose a unified view of these distinct methodologies through a new lower bound approach called \emph{interactive Fano method}. As an application, we introduce a novel complexity measure, the \emph{Fractional Covering Number}, which facilitates the new lower bounds for interactive decision making that extend the DEC methodology by incorporating the complexity of estimation. Using the fractional covering number, we (i) provide a unified characterization of learnability for \emph{any} stochastic bandit problem, (ii) close the remaining gap between the upper and lower bounds in Foster et al. (2021, 2023) (up to polynomial factors) for any interactive decision making problem in which the underlying model class is convex.
DiffLM: Controllable Synthetic Data Generation via Diffusion Language Models
Zhou, Ying, Wang, Xinyao, Niu, Yulei, Shen, Yaojie, Tang, Lexin, Chen, Fan, He, Ben, Sun, Le, Wen, Longyin
Recent advancements in large language models (LLMs) have significantly enhanced their knowledge and generative capabilities, leading to a surge of interest in leveraging LLMs for high-quality data synthesis. However, synthetic data generation via prompting LLMs remains challenging due to LLMs' limited understanding of target data distributions and the complexity of prompt engineering, especially for structured formatted data. To address these issues, we introduce DiffLM, a controllable data synthesis framework based on variational autoencoder (VAE), which further (1) leverages diffusion models to reserve more information of original distribution and format structure in the learned latent distribution and (2) decouples the learning of target distribution knowledge from the LLM's generative objectives via a plug-and-play latent feature injection module. As we observed significant discrepancies between the VAE's latent representations and the real data distribution, the latent diffusion module is introduced into our framework to learn a fully expressive latent distribution. Evaluations on seven real-world datasets with structured formatted data (i.e., Tabular, Code and Tool data) demonstrate that DiffLM generates high-quality data, with performance on downstream tasks surpassing that of real data by 2%-7% in certain cases. The data and code will be publicly available upon completion of internal review. Data Synthesis has become an indispensable technique in current machine learning research, enabling rapid generation and modification of datasets (Bauer et al., 2024), allowing researchers to experiment with various scenarios and model architectures without the extensive processes associated with real-world data collection. Meanwhile, with the rapid advancements in large language models (LLMs), recent research in natural language processing (NLP) has increasingly focused on leveraging LLMs for synthetic data generation. Early efforts attempted to fine-tune LLMs to align with real data distributions (Keskar et al., 2019; Anaby-Tavor et al., 2020; Borisov et al., 2023). As the in-context learning capabilities of LLMs have improved, some studies have explored zero-shot or few-shot prompting of LLMs to generate synthetic data (Ye et al., 2022a; Wei et al., 2024).
LLMCO2: Advancing Accurate Carbon Footprint Prediction for LLM Inferences
Fu, Zhenxiao, Chen, Fan, Zhou, Shan, Li, Haitong, Jiang, Lei
Throughout its lifecycle, a large language model (LLM) generates a substantially larger carbon footprint during inference than training. LLM inference requests vary in batch size, prompt length, and token generation number, while cloud providers employ different GPU types and quantities to meet diverse service-level objectives for accuracy and latency. It is crucial for both users and cloud providers to have a tool that quickly and accurately estimates the carbon impact of LLM inferences based on a combination of inference request and hardware configurations before execution. Estimating the carbon footprint of LLM inferences is more complex than training due to lower and highly variable model FLOPS utilization, rendering previous equation-based models inaccurate. Additionally, existing machine learning (ML) prediction methods either lack accuracy or demand extensive training data, as they inadequately handle the distinct prefill and decode phases, overlook hardware-specific features, and inefficiently sample uncommon inference configurations. We introduce \coo, a graph neural network (GNN)-based model that greatly improves the accuracy of LLM inference carbon footprint predictions compared to previous methods.
CausalVE: Face Video Privacy Encryption via Causal Video Prediction
Huang, Yubo, Feng, Wenhao, Lai, Xin, Wang, Zixi, Xu, Jingzehua, Zhang, Shuai, He, Hongjie, Chen, Fan
Advanced facial recognition technologies and recommender systems with inadequate privacy technologies and policies for facial interactions increase concerns about bioprivacy violations. With the proliferation of video and live-streaming websites, public-face video distribution and interactions pose greater privacy risks. Existing techniques typically address the risk of sensitive biometric information leakage through various privacy enhancement methods but pose a higher security risk by corrupting the information to be conveyed by the interaction data, or by leaving certain biometric features intact that allow an attacker to infer sensitive biometric information from them. To address these shortcomings, in this paper, we propose a neural network framework, CausalVE. We obtain cover images by adopting a diffusion model to achieve face swapping with face guidance and use the speech sequence features and spatiotemporal sequence features of the secret video for dynamic video inference and prediction to obtain a cover video with the same number of frames as the secret video. In addition, we hide the secret video by using reversible neural networks for video hiding so that the video can also disseminate secret data. Numerous experiments prove that our CausalVE has good security in public video dissemination and outperforms state-of-the-art methods from a qualitative, quantitative, and visual point of view. With the widespread adoption of smart devices and the Internet of Things (IoT), the security issues of biological face privacy are becoming increasingly unavoidable. The explosion of public face video distribution for IoT, exemplified by YouTube, TikTok, and Instagram, makes it difficult to protect face privacy during video interaction and distribution. In addition, the autonomy of public face video distribution and interaction on video websites means that disguised face videos must convey the same visual video information effect as the original video and hide sensitive personal privacy information. Current face privacy measures mainly focus on destroying or hiding facial attributes. In video sequences, face attributes are destroyed by replacing the region where the person is located with blank information (Newton et al., 2005; Meden et al., 2018) or by blurring and pixellating face attributes from the detector (Sarwar et al., 2018). These methods directly damage the biometric features in facial videos, destroying the usability of data interactions and even failing to leave any useful information in interactions and propagation.
Near-Optimal Learning and Planning in Separated Latent MDPs
Chen, Fan, Daskalakis, Constantinos, Golowich, Noah, Rakhlin, Alexander
Reinforcement Learning (Kaelbling et al., 1996; Sutton and Barto, 2018) captures the common challenge of learning a good policy for an agent taking a sequence of actions in an unknown, dynamic environment, whose state transitions and reward emissions are influenced by the actions taken by the agent. Reinforcement learning has recently contributed to several headline results in Deep Learning, including Atari (Mnih et al., 2013), Go (Silver et al., 2016), and the development of Large Language Models (Christiano et al., 2017; Stiennon et al., 2020; Ouyang et al., 2022). This practical success has also sparked a burst of recent work on expanding its algorithmic, statistical and learning-theoretic foundations, towards bridging the gap between theoretical understanding and practical success. In general, the agent might not fully observe the state of the environment, instead having imperfect observations of its state. Such a setting is captured by the general framework of Partially Observable Markov Decision Processes (POMDPs) (Smallwood and Sondik, 1973).
JustQ: Automated Deployment of Fair and Accurate Quantum Neural Networks
Wang, Ruhan, Baba-Yara, Fahiz, Chen, Fan
Despite the success of Quantum Neural Networks (QNNs) in decision-making systems, their fairness remains unexplored, as the focus primarily lies on accuracy. This work conducts a design space exploration, unveiling QNN unfairness, and highlighting the significant influence of QNN deployment and quantum noise on accuracy and fairness. To effectively navigate the vast QNN deployment design space, we propose JustQ, a framework for deploying fair and accurate QNNs on NISQ computers. It includes a complete NISQ error model, reinforcement learning-based deployment, and a flexible optimization objective incorporating both fairness and accuracy. Experimental results show JustQ outperforms previous methods, achieving superior accuracy and fairness. This work pioneers fair QNN design on NISQ computers, paving the way for future investigations.
IoTCO2: Assessing the End-To-End Carbon Footprint of Internet-of-Things-Enabled Deep Learning
Faiz, Ahmad, Attari, Shahzeen, Buck, Gayle, Chen, Fan, Jiang, Lei
Consequently, the global count of IoT devices is projected (DL) models are increasingly deployed on Internet of Things to grow annually by approximately 40% [17], accompanied by a (IoT) devices for data processing, significantly increasing the carbon significant increase in their carbon footprint attributable to both usage footprint associated with DL on IoT, covering both operational and manufacturing. It is anticipated that the carbon emissions and embodied aspects. Existing operational energy predictors often stemming from IoT devices may surpass those of global data centers overlook quantized DL models and emerging neural processing by 2028 [17]. Despite extensive prior investigations [4] delving into units (NPUs), while embodied carbon footprint modeling tools the carbon footprint of MLaaS in cloud environments, a notable gap neglect non-computing hardware components common in IoT devices, remains in the comprehensive assessment of the carbon footprint creating a gap in accurate carbon footprint modeling tools for associated with DL models executed on IoT devices.