an-exact-instrument-for-state-usage-in-selective-state-space-models-and-the-input-driven-migration-it-reveals-eba45e86·1 events·first seen Aliases: An Exact Instrument for State Usage in Selective State-Space Models, and the Input-Driven Migration It Reveals
A new arXiv paper introduces an exact analytical instrument for measuring how selective state-space models (Mamba-1, Mamba-2, Falcon-Mamba) allocate their state modes across inputs, using a per-(layer, channel, window) Gram tensor that predicts pruning error to near-machine-precision. The key empirical finding is that trained models dynamically reallocate which modes carry signal depending on the input context, and that this migration is driven primarily by the input-dependent write map B_t rather than the timestep parameter typically associated with selectivity. Input-scheduled mode pruning based on this instrument outperforms static and Hankel-based rankings at all scales tested (130M–7B), matching unpruned model quality at half the state budget in offline evaluation.