Val Min Abs nat Abs le
ArkLib.Lattices.CyclotomicModulus.valMinAbs_natAbs_le
Plain-language statement
The centered representative valMinAbs has the least absolute value among all integer representatives of a residue class.
Exact Lean statement
theorem valMinAbs_natAbs_le {a : ZMod q} (m : ℤ) (h : (m : ZMod q) = a) :
a.valMinAbs.natAbs ≤ m.natAbsFormal artifact
Lean source
theorem valMinAbs_natAbs_le {a : ZMod q} (m : ℤ) (h : (m : ZMod q) = a) : a.valMinAbs.natAbs ≤ m.natAbs := by have hmem := ZMod.valMinAbs_mem_Ioc a rw [Set.mem_Ioc] at hmem have hcast : (m : ZMod q) = ((a.valMinAbs : ℤ) : ZMod q) := by rw [h, ZMod.coe_valMinAbs] rw [ZMod.intCast_eq_intCast_iff_dvd_sub] at hcast obtain ⟨t, ht⟩ := hcast have hq : (1 : ℤ) ≤ (q : ℤ) := by exact_mod_cast Nat.one_le_iff_ne_zero.mpr (NeZero.ne q) rcases eq_or_ne t 0 with ht0 | ht0 · subst ht0; simp only [mul_zero] at ht; omega · have habs : q ≤ ((q : ℤ) * t).natAbs := by have ht1 : 1 ≤ t.natAbs := Int.natAbs_pos.mpr ht0 rw [Int.natAbs_mul]; simp only [Int.natAbs_natCast]; nlinarith [ht1] revert ht habs generalize (q : ℤ) * t = k intro ht habs omega- Project
- ArkLib
- License
- Apache-2.0
- Commit
- fad5cbf80877
- Source
- ArkLib/Data/Lattices/CyclotomicRing/NormBounds/Basic.lean:45-61
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Project documentation
This lemma proves the final algebraic step in the DG25 Theorem 3.1 proof. It shows that if R > e + 1, then e * (R / (R - 1)) < e + 1. The intuition is that the fraction R / (R - 1) is always greater than 1, but as R gets larger, it gets closer to 1. The hypothesis R > e + 1 provides a strong enough bound to ensure the product e * (fraction) do...
Source project: ArkLib
Person-level attribution pending.
Gadget Decompose coeff
ArkLib.Lattices.Ajtai.gadgetDecompose_coeff
Plain-language statement
The k-th coefficient (k < deg φ) of a gadget-decomposition block is exactly the corresponding digit of the corresponding input coefficient.
Source project: ArkLib
Person-level attribution pending.
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ArkLib.Lattices.Ajtai.gadgetDecompose_lawful
Plain-language statement
The base-b gadget decomposition is a lawful gadget decomposition.
Source project: ArkLib
Person-level attribution pending.