Replace dense long-range token interactions with sparse message passing on a balanced hierarchical tree. Boundary token features are extended to internal tree nodes by weighted harmonic relaxation, and the resulting weighted normal derivative is used as a learned multiscale interaction or regularization signal.
Use the min-plus phase transition as a training-time controller: begin near p = 1/2 to preserve the initial active-state fraction across depth, then move above or below criticality to deliberately remove or create sparse pathways. The controller uses a measurable state variable, the activation zero fraction, rather than an arbitrary regularization coefficient.
Insert a learnable semigroup layer that evolves features according to a positive operator combining frequency damping and spatially varying confinement. Unlike isotropic Gaussian smoothing, the layer can damp selected frequencies differently along different axes and can suppress activations in learned spatial regions, while the positive-semigroup construction prevents amplification.