Poisson likelihood models have been prevalently used in imaging, social networks, and time series analysis. We propose fast, simple, theoretically-grounded, and versatile, optimization algorithms for Poisson likelihood modeling. The Poisson log-likelihood is concave but not Lipschitz-continuous. Since almost all gradient-based optimization algorithms rely on Lipschitz-continuity, optimizing Poisson likelihood models with a guarantee of convergence can be challenging, especially for large-scale problems.
We present a new perspective allowing to efficiently optimize a wide range of penalized Poisson likelihood objectives. We show that an appropriate saddle point reformulation enjoys a favorable geometry and a smooth structure. Therefore, we can design a new gradient-based optimization algorithm with $O(1/t)$ convergence rate, in contrast to the usual $O(1/\sqrt{t})$ rate of non-smooth minimization alternatives. Furthermore, in order to tackle problems with large samples, we also develop a randomized block-decomposition variant that enjoys the same convergence rate yet more efficient iteration cost.
Experimental results on several point process applications including social network estimation and temporal recommendation show that the proposed algorithm and its randomized block variant outperform existing methods both on synthetic and real-world datasets.
ItDPDM: Information-Theoretic Discrete Poisson Diffusion Model
Department of Electrical Engineering, Stanford University（斯坦福大学电气工程系）；Department of Computer Science, Oklahoma University（俄克拉荷马大学计算机科学系）；School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN, USA（普渡大学电气与计算机工程学院）
Fast and Robust Likelihood-Guided Diffusion Posterior Sampling with Amortized Variational Inference
Institute of Foundation Models, MBZUAI（基础模型研究所，MBZUAI）；Huawei Lagrange Mathematics and Computing Research Center, Paris, France（华为拉格朗日数学与计算研究中心，法国巴黎）；Mohamed Bin Zayed University of AI, Chair of the ML Department, EPITA, Laboratoire Recherche de l'EPITA（穆罕默德·本·扎耶德人工智能大学，机器学习系主任，EPITA，EPITA研究实验室）
