arXiv Machine Learning By Huanran Chen, Huaqing Zhang, Xiao Li, Yinpeng Dong, Ke Shen, Jun Zhu

Nexus: Same Pretraining Loss, Better Downstream Generalization via Common Minima

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The paper introduces Nexus, an optimizer that encourages gradient similarity during pretraining to bring task‑specific minima closer together. Experiments on models from 130M to 3B parameters show that Nexus achieves the same pretraining loss as standard optimizers while significantly improving downstream performance, including a 15% accuracy boost on GSM8k and a 0.012 reduction in out‑of‑distribution loss for the 3B model.

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