Deep Neural Networks and Reinforcement Learning methods have empirically shown great promise in tackling challenging combinatorial problems. In those methods a deep neural network is used as a solution generator which is then trained by gradient-based methods (e.g., policy gradient) to successively obtain better solution distributions. In this work we introduce a novel theoretical framework for analyzing the effectiveness of such methods. We ask whether there exist generative models that (i) are expressive enough to generate approximately optimal solutions; (ii) have a tractable, i.e, polynomial in the size of the input, number of parameters; (iii) their optimization landscape is benign in the sense that it does not contain sub-optimal stationary points. Our main contribution is a positive answer to this question. Our result holds for a broad class of combinatorial problems including Max- and Min-Cut, Max-$k$-CSP, Maximum-Weight-Bipartite-Matching, and the Traveling Salesman Problem. As a byproduct of our analysis we introduce a novel regularization process over vanilla gradient descent and provide theoretical and experimental evidence that it helps address vanishing-gradient issues and escape bad stationary points.

深度神经网络和强化学习方法在解决复杂的组合问题方面取得了显著的实证成果，本文引入了一种新的理论框架来分析这些方法的有效性，回答了存在生成模型能够生成近似最优解、拥有易处理的参数数量以及优化结果无次优静态点等问题，并介绍了一种新的正则化过程，实验证明其有助于解决梯度消失和避免不良静态点的问题。

优化解决方案采样器的组合问题：策略梯度方法的景观