arXiv Machine Learning

Stimulus symmetries can confound representational similarity analyses

The paper investigates how symmetries in network inputs can mislead representational similarity analyses (RSAs). It shows that functionally equivalent representations, arising from stimulus symmetries, can produce distinct RSMs that depict different representational geometries—from disentangled to maximally mixed. The authors demonstrate that training dynamics such as stochastic gradient descent or energetic regularization can yield sparse, drifting codes, causing RSMs to drift over time, and that these effects also appear in networks trained on image data with latent symmetries.

arXiv Machine Learning
Oct 2

Not all solutions are created equal: An analytical dissociation of functional and representational similarity in deep linear neural networks

The paper investigates the relationship between representation and function in neural networks, using analytical two‑layer linear models and simulations of nonlinear networks. It demonstrates that functional similarity and representational similarity can be dissociated: networks may share representations without sharing functions, and vice versa. The study also finds that robustness to input noise or generalization error does not constrain representations, whereas robustness to parameter noise forces networks to adopt task‑specific representations, indicating that representational alignment reflects computational advantages beyond mere functional alignment.

By Lukas Braun, Erin Grant, Andrew M. Saxe
arXiv Machine Learning
Oct 2

Parameter symmetries determine representational geometry in overparameterized nonlinear networks

The paper investigates how parameter symmetries in overparameterized nonlinear neural networks affect representational geometry. It shows that these symmetries can be described by three basic feature transformations—addition, duplication, and scaling—allowing a closed‑form decomposition of representations into essential and auxiliary parts. The study further demonstrates that implementation‑level selection rules can resolve the resulting degeneracy, producing identifiable geometries that reflect feature contributions to the network’s function.

By Marvin Theiss, Lukas Braun, Andrew M. Saxe, Erin Grant
arXiv Machine Learning
Jun 24

Similarity of Neural Network Representations in Superposition

arXiv:2604. 00208v2 Announce Type: replace Abstract: Comparing internal representations is a central goal in neuroscience and machine learning, but standard linear alignment metrics (Representational Similarity Analysis, Centered Kernel Alignment, and linear regression) are frequently applied to neural activity coordinates rather than on the underlying features.

By Sunny Liu, Habon Issa, Andr\'e Longon, Liv Gorton, Meenakshi Khosla, Alex Williams, David Klindt
arXiv Machine Learning
Oct 5

Broken scale symmetries in undercomplete linear autoencoders

The paper investigates how finite‑stepsize stochastic gradient descent (SGD) breaks scale symmetry in undercomplete linear autoencoders. It shows that SGD induces a directed scale drift that favors large decoder weights on the PCA solution manifold, a process that is slow and analytically tractable but eventually halted by a stability boundary. The resulting solutions exhibit sharper loss Hessians compared to a balanced baseline, illustrating how loss geometry can transform residual gradient noise into directed motion along equivalent solution manifolds.

By Farhad Pashakhanloo, Jacob A. Zavatone-Veth
arXiv Machine Learning
5d ago

Graph Metanetworks for Transformer Based Language Models

The paper introduces graph metanetworks for transformer-based language models, addressing the challenge that different weight configurations can implement the same function due to a rich symmetry group. It formalizes a weight‑space symmetry group for complete decoder‑only language models and presents a graph construction invariant to these symmetries. The authors also create two new transformer‑population datasets with tasks like training‑corpus prediction and fine‑tuning detection, where their method outperforms existing baselines.

By Yonathan Wolanowsky, Guy Bar-Shalom, Fabrizio Frasca, Haggai Maron
arXiv Machine Learning
Sep 3

Emergence of Fibrations, Compression, and Symmetry Breaking in Artificial Neural Networks

Artificial neural networks generate local symmetries called fibrations and coverings during learning, and these covering symmetries are stable attractors of stochastic gradient descent. The study shows that such symmetries appear across diverse architectures—multilayer, convolutional, recurrent, and transformer networks—and can be exploited for drastic model compression, reducing networks to 17% of their original size without performance loss. Controlled breaking of covering symmetry further improves continual learning, achieving state‑of‑the‑art results.

By Osvaldo M Velarde, Lucas C Parra, Alireza Hashemi, Hernan A Makse