Impact of Positional Encoding: Clean and Adversarial Rademacher Complexity for Transformers under In-Context Regression
arXiv:2512.09275v2 Announce Type: replace Abstract: Positional encoding (PE) is a core architectural component of Transformers, yet its impact on the Transformer’s generalization and robustness remains unclear. In this work, we provide the first generalization analysis for a single-layer Transformer under in-context regression that explicitly accounts for a completely trainable PE module. Our result shows that PE systematically enlarges the generalization gap. Extending to the adversarial setting, we derive the adversarial Rademacher generalization bound. We find that the gap […]