揭示神经网络极小极大博弈的收敛秘密,为对抗训练等应用提供理论支撑。
Solving Neural Min-Max Games: The Role of Architecture, Initialization & Dynamics
- 通过隐藏凸性与过参数化分析,建立收敛条件
- 证明两层神经网络可全局收敛至纳什均衡
- 适合研究博弈优化、对齐安全的学者参考
许多新兴应用如对抗训练、人工智能对齐和鲁棒优化可建模为神经网络间的零和博弈,冯·诺依曼-纳什均衡(NE)刻画理想系统行为。尽管目标函数通常非凸非凹,但实验表明简单梯度方法常能收敛,暗示隐藏几何结构的存在。本文从隐藏凸性和过参数化角度,提出理论框架,识别出保证在一大类非凸极小极大博弈中全局收敛至NE的充分条件,涵盖初始化、训练动态与网络宽度。据我们所知,这是首个针对含两层神经网络的此类结果。技术上,一方面推导出交替梯度下降-上升方案的新型路径长度界;另一方面,在过参数化下,利用随机矩阵理论证明从隐藏凸-凹几何到双侧Polyak-Łojasiewicz(PŁ)极小极大条件的转化以高概率成立。
原文摘要 · Abstract (English)
Many emerging applications - such as adversarial training, AI alignment, and robust optimization - can be framed as zero-sum games between neural nets, with von Neumann-Nash equilibria (NE) capturing the desirable system behavior. While such games often involve non-convex non-concave objectives, empirical evidence shows that simple gradient methods frequently converge, suggesting a hidden geometric structure. In this paper, we provide a theoretical framework that explains this phenomenon through the lens of hidden convexity and overparameterization. We identify sufficient conditions - spanning initialization, training dynamics, and network width - that guarantee global convergence to a NE in a broad class of non-convex min-max games. To our knowledge, this is the first such result for games that involve two-layer neural networks. Technically, our approach is twofold: (a) we derive a novel path-length bound for the alternating gradient descent-ascent scheme in min-max games; and (b) we show that the reduction from a hidden convex-concave geometry to two-sided Polyak-Łojasiewicz (PŁ) min-max condition hold with high probability under overparameterization, using tools from random matrix theory.
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