Quantitative trimming after restrictions of a leaf mixture
Lax342547.LeafTrimming · concepts/Lax342547/LeafTrimming.lean · lax-342547
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Theorem
Small retained fractions are discarded with their actual mixture weights. The normalized surviving leaves preserve image bounds with an explicit loss, while marginal bounds are tracked on the restricted mixed law.
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Evidence
This concept declares 7 statements. Each proof establishes one of them relative to its assumptions.
1 combined_restriction proven
2 density_after_restriction proven
3 event_after_restriction proven
4 filtered_marginal proven
5 minentropy_after_restriction proven
6 restricted_discard proven
7 weighted_discard proven
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| 1 | import Lax342547.Conditioning |
| 2 | import Mathlib.Analysis.SpecialFunctions.Pow.NNReal |
| 3 | |
| 4 | /-! |
| 5 | --- |
| 6 | title: Quantitative trimming after restrictions of a leaf mixture |
| 7 | type: theorem |
| 8 | --- |
| 9 | Small retained fractions are discarded with their actual mixture weights. |
| 10 | The normalized surviving leaves preserve image bounds with an explicit |
| 11 | loss, while marginal bounds are tracked on the restricted mixed law. |
| 12 | -/ |
| 13 | |
| 14 | namespace Lax342547.LeafTrimming |
| 15 | |
| 16 | open scoped ENNReal |
| 17 | |
| 18 | noncomputable def discardedMass {J : Type} [Fintype J] |
| 19 | (w q : J → ℝ≥0∞) (δ : ℝ≥0∞) : ℝ≥0∞ := |
| 20 | ∑ j, if q j < δ then w j * q j else 0 |
| 21 | |
| 22 | axiom weighted_discard {J : Type} [Fintype J] (w q : J → ℝ≥0∞) |
| 23 | (δ : ℝ≥0∞) (hw : ∑ j, w j ≤ 1) : discardedMass w q δ ≤ δ |
| 24 | |
| 25 | axiom restricted_discard {J : Type} [Fintype J] (w q : J → ℝ≥0∞) |
| 26 | (ζ η : ℝ) (N : ℕ) (hw : ∑ j, w j ≤ 1) |
| 27 | (hq : (2 : ℝ≥0∞) ^ (-(η * N)) ≤ ∑ j, w j * q j) : |
| 28 | discardedMass w q ((2 : ℝ≥0∞) ^ (-(ζ * N))) / (∑ j, w j * q j) ≤ |
| 29 | (2 : ℝ≥0∞) ^ (-((ζ - η) * N)) |
| 30 | |
| 31 | axiom event_after_restriction {Ω : Type} [Fintype Ω] (p : PMF Ω) |
| 32 | (S T : Set Ω) (hS : ∃ o ∈ S, o ∈ p.support) (τ b : ℝ≥0∞) |
| 33 | (hτ : τ ≤ p.toOuterMeasure S) (hb : p.toOuterMeasure T ≤ b) : |
| 34 | (p.filter S hS).toOuterMeasure T ≤ b / τ |
| 35 | |
| 36 | axiom minentropy_after_restriction {Ω : Type} [Fintype Ω] (p : PMF Ω) |
| 37 | (S T : Set Ω) (hS : ∃ o ∈ S, o ∈ p.support) (ζ : ℝ) (N t : ℕ) |
| 38 | (hζ : 0 ≤ ζ) (ht : 1 ≤ t) |
| 39 | (hSbound : (2 : ℝ≥0∞) ^ (-(ζ * N)) ≤ p.toOuterMeasure S) |
| 40 | (hTbound : p.toOuterMeasure T ≤ (2 : ℝ≥0∞) ^ (-((1 - ζ) * t * N))) : |
| 41 | (p.filter S hS).toOuterMeasure T ≤ (2 : ℝ≥0∞) ^ (-((1 - 2 * ζ) * t * N)) |
| 42 | |
| 43 | axiom density_after_restriction {Ω : Type} (p μ : PMF Ω) |
| 44 | (S : Set Ω) (hS : ∃ o ∈ S, o ∈ p.support) (C ζ : ℝ) (N : ℕ) |
| 45 | (hSbound : (2 : ℝ≥0∞) ^ (-(ζ * N)) ≤ p.toOuterMeasure S) |
| 46 | (hp : ∀ o, p o ≤ (2 : ℝ≥0∞) ^ (C * N) * μ o) : |
| 47 | ∀ o, (p.filter S hS) o ≤ (2 : ℝ≥0∞) ^ ((C + ζ) * N) * μ o |
| 48 | |
| 49 | axiom filtered_marginal {Ω V : Type} [Fintype Ω] (p : PMF Ω) (μ : PMF V) |
| 50 | (f : Ω → V) (S : Set Ω) (hS : ∃ o ∈ S, o ∈ p.support) |
| 51 | (M : ℝ≥0∞) (hp : ∀ v, p.map f v ≤ M * μ v) : |
| 52 | ∀ v, (p.filter S hS).map f v ≤ (M / p.toOuterMeasure S) * μ v |
| 53 | |
| 54 | axiom combined_restriction {Ω : Type} [Fintype Ω] (p : PMF Ω) (S T : Set Ω) |
| 55 | (hS : ∃ o ∈ S, o ∈ p.support) |
| 56 | (hT : ∃ o ∈ T, o ∈ (p.filter S hS).support) |
| 57 | (hST : ∃ o ∈ S ∩ T, o ∈ p.support) : |
| 58 | (p.filter S hS).filter T hT = p.filter (S ∩ T) hST |
| 59 | |
| 60 | end Lax342547.LeafTrimming |
| 61 |
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