Within a prediction task, Graph Neural Networks (GNNs) use relational information as an inductive bias to enhance the model's accuracy. As task-relevant relations might be unknown, graph structure learning approaches have been proposed to learn them while solving the downstream prediction task. In this paper, we demonstrate that minimization of a point-prediction loss function, e.g., the mean absolute error, does not guarantee proper learning of the latent relational information and its associated uncertainty. Conversely, we prove that a suitable loss function on the stochastic model outputs simultaneously grants (i) the unknown adjacency matrix latent distribution and (ii) optimal performance on the prediction task. Finally, we propose a sampling-based method that solves this joint learning task. Empirical results validate our theoretical claims and demonstrate the effectiveness of the proposed approach.

该研究展示了在预测任务中，图神经网络（GNNs）利用关系信息作为归纳偏差以提高模型的准确性。通过学习图结构的方法来解决下游预测任务中未知的相关关系，同时证明了点预测损失函数（如平均绝对误差）的最小化并不能保证对潜在关系信息及其相关不确定性进行适当的学习。相反，合适的损失函数在随机模型输出上同时确保了（i）未知邻接矩阵潜在分布和（ii）在预测任务上的最佳性能。最后，我们提出了一种基于采样的方法来解决这一联合学习任务。实证结果验证了我们的理论观点，并证明了所提方法的有效性。

学习潜在的图结构及其不确定性