Machine-learning ideas tagged Lie groups in the Math taxonomy of the Math2NN corpus.
Replace ordinary pairwise attention similarity by an affinity averaged over transformed keys or values. The resulting attention is invariant to the group action on either input and avoids requiring the network to learn identical attention patterns for every rotated or transformed copy.
Represent each token value in an attention head as a bounded three-dimensional Lie-algebra vector and impose a weighted polygon-closure condition on the aggregate value vectors. The module is invariant to a common \(SU(2)\simeq SO(3)\) rotation of all token vectors, preventing the head from spending capacity on an arbitrary global orientation. A soft closure penalty gives a drop-in experiment, while projection onto the zero-sum manifold provides a harder constrained variant.
Add a profile-preserving exchange layer that mixes representations through pairwise state swaps, with weights shared over all positions. Unlike ordinary token-wise MLP mixing, the layer explicitly models interactions between two categorical states while respecting the symmetry of position permutations.
Replace explicit quotient construction by a differentiable projection that removes learned group-orbit directions from both source and target features. The paper's reduction argument shows that a closed level constraint makes the restricted form horizontal, so the network can operate on invariant coordinates while retaining a measurable residual for symmetry leakage.
Replace an unconstrained low-rank adapter or similarity projection with a learned subspace carrying a prescribed signed metric. The module learns an orthonormal basis U for a k=p+q dimensional subspace, forces the compressed form U^*I_{m,n}U to have p positive and q negative eigenvalues, and uses the resulting pseudo-inner product for signed attention or retrieval scores.
Replace or augment standard sinusoidal or RoPE position features with bracket-quadratic phases $e(-\theta n\lfloor\beta n\rfloor)$ generated by a Heisenberg nilmanifold orbit. Multiple irrational coefficients and output frequencies produce a cheap deterministic encoding whose empirical cross-position correlations should exhibit cancellation instead of the periodic aliasing of rational or finite-frequency encodings.
Replace a locally oriented three-channel feature frame by its positive-definite polar factor, removing arbitrary SO(3) basis rotations before the feature enters an MLP, attention block, or graph message-passing layer. Process the resulting SPD matrix in log coordinates so the downstream network receives a globally unconstrained symmetric representation rather than a gauge-dependent frame.
Represent a population of N circular latent states using a three-parameter Möbius transformation applied to fixed uniform reference phases, rather than learning N unrelated angles. The resulting states remain on the circle by construction and can model concentrated or nearly uniform phase populations through a single concentration parameter.