Graph Neural Networks (GNNs) have achieved impressive performance in
collaborative filtering. However, GNNs tend to yield inferior performance when
the distributions of training and test data are not aligned well. Also,
training GNNs requires optimizing non-convex neural networks with an abundance
of local and global minima, which may differ widely in their performance at
test time. Thus, it is essential to choose the minima carefully. Here we
propose an effective training schema, called {gSAM}, under the principle that
the \textit{flatter} minima has a better generalization ability than the
\textit{sharper} ones. To achieve this goal, gSAM regularizes the flatness of
the weight loss landscape by forming a bi-level optimization: the outer problem
conducts the standard model training while the inner problem helps the model
jump out of the sharp minima. Experimental results show the superiority of our
gSAM.

图神经网络在协同过滤中取得了令人印象深刻的性能，然而，当训练数据和测试数据的分布不足够一致时，图神经网络的性能会较差。由于训练图神经网络需要优化充满局部和全局极值的非凸神经网络，这些极值在测试时可能性能差异很大，因此选择极值非常重要。因此，我们提出了一种名为 gSAM 的有效训练模式，该模式的原则是较为平坦的极值具有更好的泛化能力。为了实现这个目标，gSAM 通过形成双层优化来规范权重损失函数的平坦度：外部问题进行标准模型训练，而内部问题则帮助模型跳出尖锐的极值。实验证明了我们的 gSAM 的优越性。