CONF Zhang_ICLR_2026/IDIAP How does the optimizer implicitly bias the model merging loss landscape? Zhang, Chenxiang Theus, Alexander Teney, Damien Orvieto, Antonio Pang, Jun Mauw, Sjouke EXTERNAL http://publications.idiap.ch/attachments/papers/2026/Zhang_ICLR_2026.pdf PUBLIC International Conference on Learning Representations 2026 https://arxiv.org/abs/2510.04686 URL