# SFT Constants and Thresholds

This ledger collects key inequalities used by the certificate validators.

| Threshold | Name | Meaning | Implication | Reference |
|---|---|---|---|---|
| LCM < π | Lift-closeness margin | degree cannot change under perturbation | LDW stability and robust winding | `finish_ready/sft2/sft2_syncre_stability_modulus.tex` |
| HMR < P/2 | Holonomy margin | holonomy class cannot change under perturbation | HW stability and robust holonomy | `finish_ready/sft2/sft2_syncre_stability_modulus.tex` |
| γ > 0 | tightness gap | separates tight vs non-tight edges (when used) | core structure stable under small perturbations | `engine/docs/quantitative_rates.md` |
| δ > 0 | Doeblin margin | minorization constant for a Doeblin word/block | projective contraction from recurrence | `engine/docs/quantitative_rates.md` |
| NDB parameters | noise-to-diffusion bridge | quantitative domination of deterministic shear by diffusion/noise | admissible mixing certificate inputs | `engine/docs/mixing_bridge_ndb.md` |

## MXC_rate_line_example

For an advection–diffusion model on T_P, a conservative sufficient line is:

  λ := 2κ(2π/P)^2 − ||∂_y u||_∞.

When λ>0, mean-zero defects decay exponentially in L2 at a rate bounded below by λ.

This line is used as a canonical ledger reference for NDB_MXC artifacts.
