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About this paper

Lavanya Nigam, Ishaan Bansal, Aryan Sood, Vidit Aggarwal, Gaurav Kumar Nayak

Researchers from the Indian Institute of Technology Roorkee found that Masked Diffusion Language Model embeddings exhibit a hyperspherical geometry, causing linear interpolation in predictive feedback to fail. They propose Spherical Soft-Masking (S-SM), which uses spherical aggregation and interpolation, leading to MAUVE score improvements of 27.7–56.1% and a reduction in generative perplexity by 12.2–14.2% over existing linear soft-masking methods.

Key insights

  • MDLM token embeddings are concentrated on a hyperspherical manifold, not a Euclidean space, with a consistent 73° geodesic angle between mask and predicted embedding directions.
  • Linear interpolation is geometrically inconsistent in a hyperspherical space, whereas spherical interpolation (SLERP) respects the intrinsic geometry, maintaining semantic fidelity.
  • The model's optimizer sustains a significantly larger feedback magnitude (higher learned λ) when using geometrically principled spherical feedback, indicating greater trust in the refined information.

Summary by alphaXiv.

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