Phantom Transitions in Language Model Fine-Tuning: A Density-Matrix Analysis

arXiv:2606.07559v3 Announce Type: replace-cross Abstract: Language models fine-tuned where the correct completion must outrank a near-synonym competitor often fail silently. The cross-entropy loss falls monotonically while the correct token never overtakes the competitor in the model's ranking. We study this across five transformer architectures from… The post Phantom Transitions in Language Model…