提出可解高维GAN模型,揭示协方差对学习稳定性的影响机制。
Effective Covariance Dynamics in Solvable High-Dimensional GANs

- 构建带结构协方差的可解GAN模型,引入类相关与非零均值特征。
- 高维极限下训练过程收敛到由有效协方差决定的确定性微分方程。
- 低秩相关可增强弱信号学习能力,但过强相关会破坏恢复稳定性。
我们研究了一种可解的高维生成对抗网络(GAN)训练模型,其中线性生成器从具有结构化潜在协方差的数据中学习低维子空间。现有可解GAN分析假设无条件信号且潜在协方差为对角阵;本文将多特征判别器设置扩展至类依赖、相关且非零均值的潜在结构。对于二次能量判别器,所有异质性均通过概率加权的有效二阶矩体现。我们证明,在高维极限下,随机微观训练过程收敛于由该有效协方差驱动的确定性常微分方程。在匹配协方差特例中,稳定性分析得出一个按模式可解的区间,由学习率与噪声水平决定:当主导有效特征值超过下界时学习开始,而完全恢复需所有相关有效模式保持在区间内。这揭示了一种信号增强机制:低秩相关可使弱方向越过可学习阈值,但过度相关会引发不稳定性。数值模拟验证了微分方程、相变边界及增强机制。在MNIST、FashionMNIST和CIFAR-10上的实验进一步表明,有指导的生成器协方差能提升与数据驱动参考子空间的对齐度。
原文摘要 · Abstract (English)
We study a solvable high-dimensional model of generative adversarial network (GAN) training in which a linear generator learns a low-dimensional subspace from data with structured latent covariance. Prior solvable GAN analyses assume unconditional signals with diagonal latent covariance; we extend the multi-feature discriminator setting to class-dependent, correlated, and non-zero-mean latent structure. For the quadratic energy discriminator, all such heterogeneity enters the dynamics through a probability-weighted effective second moment. We prove that the stochastic microscopic training process converges, in the high-dimensional limit, to deterministic ordinary differential equations governed by this effective covariance. In the matched-covariance specialization, the stability analysis yields a mode-wise solvable interval determined by the learning rates and noise level: learning begins when the leading effective eigenvalue crosses the lower threshold, while full recovery requires all relevant effective modes to remain within the interval. This reveals a signal-boosting mechanism: low-rank correlations can lift weak directions above the learnability threshold, whereas overly strong correlations destabilize recovery. Numerical simulations validate the ODE, phase boundary, and boosting mechanism. Experiments on MNIST, FashionMNIST, and CIFAR-10 further show that informed generator covariance improves alignment with the data-driven reference subspace.
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