Gradient-Gated DPO: Stabilizing Preference Optimization in Language Models
Direct Preference Optimization (DPO) improves relative preference by increasing the margin between chosen and rejected responses, but this objective does not specify how probability mass should be redistributed to achieve that margin. Consequently, preference separation can improve even as probability mass collapses away from both preferred and unrelated responses, a phenomenon associated with the squeezing effect. We show that this pathology is localized: continued negative updates become destructive when rejected responses enter low-probability valleys, where further suppression induces harmful redistribution through the coupled softmax geometry. We introduce Gradient-Gated Preference O...
| Authors | Inoussa Mouiche, Abderaouf Bahi |
|---|---|
| Primary category | cs.LG |
| Published | 4 May 2026 |
| Last updated at source | 21 September 2026 |
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