Generative adversarial networks (GAN) approximate a target data distribution by jointly optimizing an objective function through a "two-player game" between a generator and a discriminator. Despite their empirical success, however, two very basic questions on how well they can approximate the target distribution remain unanswered. First, it is not known how restricting the discriminator family affects the approximation quality. Second, while a number of different objective functions have been proposed, we do not understand when convergence to the global minima of the objective function leads to convergence to the target distribution under various notions of distributional convergence. In this paper, we address these questions in a broad and unified setting by defining a notion of adversarial divergences that includes a number of recently proposed objective functions. We show that if the objective function is an adversarial divergence with some additional conditions, then using a restricted discriminator family has a moment-matching effect. Additionally, we show that for objective functions that are strict adversarial divergences, convergence in the objective function implies weak convergence, thus generalizing previous results.

本文研究了生成对抗网络在逼近目标分布时的两个基本问题：限制鉴别器家族对近似质量的影响和不同目标函数的收敛条件与分布收敛之间的关系。定义了对抗分歧的概念，证明了使用受限制的鉴别器家族具有矩匹配效应，并且对于严格对抗性分歧的目标函数，证明了目标函数上的收敛蕴含着弱收敛。

生成对抗学习的逼近与收敛特性