Rounding and degree-budget arithmetic for sparse field sizes #
The upper logarithm rounds the field bit length to twice a power of three. Ceiling division controls the coordinate count. The rate inequality is integer-valued, so no logarithm or real rounding convention is hidden.
theorem
Algebraic.Cutwidth.Extractor.Internal.sparsePowerBits_pos
{u T : ℕ}
(rate : 0 < u)
(positive : 0 < T)
:
theorem
Algebraic.Cutwidth.Extractor.Internal.condenserCoordinates_capacity
{k r : ℕ}
(positive : 0 < r)
:
theorem
Algebraic.Cutwidth.Extractor.Internal.condenserCoordinates_le
{k r : ℕ}
(positive : 0 < r)
:
theorem
Algebraic.Cutwidth.Extractor.Internal.sparseCondenser_output
{u T k : ℕ}
:
u * (condenserCoordinates k (sparsePowerBits u T) * sparseFieldBits u T) ≤ (u + 1) * k + u * sparseFieldBits u T
theorem
Algebraic.Cutwidth.Extractor.Internal.sparseCondenser_loss
{u T D k : ℕ}
{error : ℝ}
(rate : 0 < u)
(positive : 0 < T)
(budget : ↑D * ↑k ≤ error * 2 ^ T)
:
↑((D - 1) * (2 ^ sparsePowerBits u T - 1) * condenserCoordinates k (sparsePowerBits u T)) / 2 ^ sparseFieldBits u T ≤ error