arXiv AI
3d ago

Effective Does Not Mean Useful: Conditional Functional Substitutability for Redundancy and Scaling in Transformers

The paper introduces Conditional Functional Substitutability (CFS) as a new way to measure redundancy in Transformers by examining when intermediate states produce similar downstream responses. CFS uncovers functional relationships and potential reductions that traditional importance- or similarity-based metrics miss, revealing systematic reorganization as models scale. Experiments across modalities and Transformer families show that performance gains do not always align with increased substitutability, and that models with more independent functional structure perform better, offering a functional explanation for diminishing returns and enabling more efficient dynamic computation.

By Jiaheng Chen, Jiaxing Li, Yucheng Xiao, Xinyong Cai, Juncheng Bu, Lan Yu, Tinghe Zhang