Research-Stack/0-Core-Formalism/lean/Semantics/Semantics/DspErasureCoding.lean

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/- Copyright (c) 2026 Sovereign Research Stack. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Authors: Research Stack Team
DspErasureCoding.lean — DSP-Aware 3-Stream Erasure Coding
This module formalizes DSP-aware erasure coding for streaming data:
- 3-stream redundancy scheme (inspired by PhiRedundancy)
- Sample-block based erasure recovery
- Q16_16 fixed-point for hardware extraction
- FPGA DSP slice integration
- Spectral-aware erasure detection
Key insight:
DSP erasure coding treats streams as continuous signals, not discrete bytes.
Spectral analysis identifies erasures in frequency domain, not just bit errors.
Per AGENTS.md §1.4: Q16_16 fixed-point for hardware extraction.
Per AGENTS.md §2: PascalCase types, camelCase functions.
Per AGENTS.md §4: Every def has eval witness or theorem.
TODO(lean-port): Connect to FPGA Warden Node AMMR accumulator
TODO(lean-port): Integrate with StreamCompression spectral analysis
-/
import Mathlib.Data.Nat.Basic
import Mathlib.Data.Fin.Basic
import Mathlib.Tactic
import Semantics.FixedPoint
namespace Semantics.DspErasureCoding
open Semantics.Q16_16
-- ═══════════════════════════════════════════════════════════════════════════
-- §0 DSP Stream Types
-- ═══════════════════════════════════════════════════════════════════════════
/-- DSP sample in Q16.16 fixed-point format. -/
abbrev DspSample := Q16_16
/-- Sample block (DSP standard processing unit). -/
structure SampleBlock where
samples : Array DspSample
blockId : Nat
deriving Repr, Inhabited
/-- Stream identifier for 3-stream redundancy. -/
inductive StreamId where
| primary -- Stream 0: original data
| recovery1 -- Stream 1: first permutation
| recovery2 -- Stream 2: second permutation
deriving Repr, DecidableEq, BEq
/-- Erasure marker for damaged samples. -/
structure ErasureMarker where
isErased : Bool
confidence : Q16_16 -- Confidence that this is truly an erasure (Q16.16)
deriving Repr, Inhabited
-- ═══════════════════════════════════════════════════════════════════════════
-- §1 3-Stream Redundancy Scheme
-- ═══════════════════════════════════════════════════════════════════════════
/-- Redundancy scheme parameters with genomic compression support (Q16.16). -/
structure RedundancyScheme where
blockSize : Nat
step1 : Nat -- Coprime to blockSize for permutation 1
step2 : Nat -- Coprime to blockSize for permutation 2
offset1 : Nat
offset2 : Nat
-- Genomic field parameters for genetic compression
rhoSeq : Q16_16 -- ρ_seq²: sequence alignment accuracy
vEpigenetic : Q16_16 -- v_epigenetic²: methylation dynamics
tauStructure : Q16_16 -- τ_structure²: 3D folding tension
sigmaEntropy : Q16_16 -- σ_entropy²: nucleotide diversity
qConservation : Q16_16 -- q_conservation²: evolutionary constraint
kappaHierarchy : Q16_16 -- κ_hierarchy²: chromatin levels
epsilonMutation : Q16_16 -- ε_mutation: mutation rate
deriving Repr
/-- Check if step is coprime to n (gcd = 1). -/
def isCoprime (n step : Nat) : Bool :=
let rec gcd (a b : Nat) : Nat :=
if b = 0 then a else gcd b (a % b)
gcd n step = 1
/-- Valid scheme requires coprime steps. -/
def isValidScheme (sch : RedundancyScheme) : Bool :=
isCoprime sch.blockSize sch.step1 ∧ isCoprime sch.blockSize sch.step2
/-- Affine permutation: π(i) = (offset + step * i) mod n. -/
def affinePerm (n step offset i : Nat) : Nat :=
(offset + step * i) % n
/-- Inverse lookup for affine permutation. -/
def affinePermInv? (n step offset target : Nat) : Option Nat :=
let rec go (j : Nat) : Option Nat :=
if j < n then
if affinePerm n step offset j = target then some j else go (j + 1)
else
none
go 0
-- ═══════════════════════════════════════════════════════════════════════════
-- §2 Stream Construction
-- ═══════════════════════════════════════════════════════════════════════════
/-- Build primary stream (identity permutation). -/
def buildPrimaryStream (sch : RedundancyScheme) (block : SampleBlock) : SampleBlock :=
{ samples := block.samples, blockId := block.blockId }
/-- Build recovery stream 1 (affine permutation). -/
def buildRecoveryStream1 (sch : RedundancyScheme) (block : SampleBlock) : SampleBlock :=
let permuted := (Array.range sch.blockSize).map (fun j =>
block.samples[affinePerm sch.blockSize sch.step1 sch.offset1 j]!
)
{ samples := permuted, blockId := block.blockId }
/-- Build recovery stream 2 (second affine permutation). -/
def buildRecoveryStream2 (sch : RedundancyScheme) (block : SampleBlock) : SampleBlock :=
let permuted := (Array.range sch.blockSize).map (fun j =>
block.samples[affinePerm sch.blockSize sch.step2 sch.offset2 j]!
)
{ samples := permuted, blockId := block.blockId }
/-- Complete 3-stream redundancy bundle. -/
structure StreamBundle where
primary : SampleBlock
recovery1 : SampleBlock
recovery2 : SampleBlock
deriving Repr, Inhabited
/-- Build complete stream bundle. -/
def buildStreamBundle (sch : RedundancyScheme) (block : SampleBlock) : StreamBundle :=
{
primary := buildPrimaryStream sch block,
recovery1 := buildRecoveryStream1 sch block,
recovery2 := buildRecoveryStream2 sch block
}
-- ═══════════════════════════════════════════════════════════════════════════
-- §3 Erasure Detection (Spectral Analysis)
-- ═══════════════════════════════════════════════════════════════════════════
/-- Detect erasures using spectral anomaly detection with genomic compression (Q16.16). -/
def detectErasureSpectral (block : SampleBlock) (threshold : Q16_16) (sch : RedundancyScheme) : Array ErasureMarker :=
-- Compute energy of each sample
let energies := block.samples.map (fun s => s * s)
let meanEnergy := div (energies.foldl (fun acc e => acc + e) zero) (ofNat energies.length)
-- Genomic field strength for adaptive threshold
let genomicNumerator := sch.rhoSeq + sch.vEpigenetic + sch.tauStructure +
sch.sigmaEntropy + sch.qConservation
let kappaSq := sch.kappaHierarchy * sch.kappaHierarchy
let geomTerm := one + kappaSq
let mutTerm := one + sch.epsilonMutation
let genomicDenom := mul geomTerm mutTerm
let genomicWeight := div genomicNumerator genomicDenom
let adaptiveThreshold := mul threshold (one + genomicWeight)
-- Mark samples with energy deviation > adaptive threshold as potential erasures
block.samples.mapIdx (fun i s =>
let deviation := abs (s * s - meanEnergy)
{
isErased := deviation > adaptiveThreshold,
confidence := if deviation > adaptiveThreshold then div deviation adaptiveThreshold else zero
}
)
/-- Detect erasures using simple threshold with genomic compression (Q16.16). -/
def detectErasureThreshold (block : SampleBlock) (threshold : Q16_16) (sch : RedundancyScheme) : Array ErasureMarker :=
-- Genomic field strength for adaptive threshold
let genomicNumerator := sch.rhoSeq + sch.vEpigenetic + sch.tauStructure +
sch.sigmaEntropy + sch.qConservation
let kappaSq := sch.kappaHierarchy * sch.kappaHierarchy
let geomTerm := one + kappaSq
let mutTerm := one + sch.epsilonMutation
let genomicDenom := mul geomTerm mutTerm
let genomicWeight := div genomicNumerator genomicDenom
let adaptiveThreshold := mul threshold (one + genomicWeight)
block.samples.map (fun s =>
{
isErased := abs s > adaptiveThreshold,
confidence := if abs s > adaptiveThreshold then div (abs s) adaptiveThreshold else zero
}
)
-- ═══════════════════════════════════════════════════════════════════════════
-- §4 Erasure Recovery
-- ═══════════════════════════════════════════════════════════════════════════
/-- Sample with optional erasure marker. -/
abbrev MarkedSample := Option DspSample
/-- Fetch sample from stream with inverse permutation. -/
def fetchSample
(stream : SampleBlock)
(inv? : Nat → Option Nat)
(logicalIdx : Nat) : MarkedSample :=
match inv? logicalIdx with
| some j =>
if j < stream.samples.size then
some stream.samples[j]!
else
none
| none => none
/-- Vote-based recovery from up to 3 candidates (Q16.16). -/
def recoverSample (c1 c2 c3 : MarkedSample) : DspSample :=
let candidates := [c1, c2, c3].filterMap id
if candidates.isEmpty then zero
else
let sum := candidates.foldl (fun acc s => acc + s) zero
div sum (ofNat candidates.length)
/-- Recover complete block from 3 streams with erasure markers. -/
def recoverBlock
(sch : RedundancyScheme)
(primary recovery1 recovery2 : SampleBlock)
(primaryMarkers recovery1Markers recovery2Markers : Array ErasureMarker)
: SampleBlock :=
let recovered := (Array.range sch.blockSize).map (fun i =>
let c1 := if primaryMarkers[i]!.isErased then none else some primary.samples[i]!
let c2 := if recovery1Markers[i]!.isErased then none
else fetchSample recovery1 (affinePermInv? sch.blockSize sch.step1 sch.offset1) i
let c3 := if recovery2Markers[i]!.isErased then none
else fetchSample recovery2 (affinePermInv? sch.blockSize sch.step2 sch.offset2) i
recoverSample c1 c2 c3
)
{ samples := recovered, blockId := primary.blockId }
-- ═══════════════════════════════════════════════════════════════════════════
-- §5 FPGA DSP Integration
-- ═══════════════════════════════════════════════════════════════════════════
/-- FPGA DSP opcode for erasure coding. -/
inductive ErasureOpcode where
| resonate -- 0x14: TSM_RESONATE / PHONON_LOCK
| mergeModes -- 0x42: TSM_MERGE_MODES
deriving Repr, DecidableEq
/-- DSP erasure coding configuration. -/
structure ErasureConfig where
opcode : ErasureOpcode
phi : Q16_16 -- Resonance parameter (1.618 for golden ratio)
clockCycles : Nat
deriving Repr
/-- Map erasure mode to FPGA opcode. -/
def modeToOpcode (mode : StreamId) : ErasureOpcode :=
match mode with
| StreamId.primary => ErasureOpcode.mergeModes
| StreamId.recovery1 => ErasureOpcode.resonate
| StreamId.recovery2 => ErasureOpcode.resonate
-- ═══════════════════════════════════════════════════════════════════════════
-- §6 Theorems
-- ═══════════════════════════════════════════════════════════════════════════
/-- Theorem: Identity permutation is its own inverse. -/
theorem identityPermutationInverse (n i : Nat) (h : i < n) :
affinePermInv? n 1 0 (affinePerm n 1 0 i) = some i := by
unfold affinePerm affinePermInv?
simp
-- Direct computation shows identity
/-- Theorem: Valid scheme has coprime steps. -/
theorem validSchemeCoprime (sch : RedundancyScheme) :
isValidScheme sch → isCoprime sch.blockSize sch.step1 ∧ isCoprime sch.blockSize sch.step2 := by
unfold isValidScheme
intro h
exact h
/-- Theorem: Recovery from 3 candidates produces weighted average. -/
theorem recoveryIsAverage (c1 c2 c3 : DspSample) :
recoverSample (some c1) (some c2) (some c3) = div (c1 + c2 + c3) (ofNat 3) := by
unfold recoverSample
simp
/-- Theorem: Erasure detection threshold is monotonic. -/
theorem erasureThresholdMonotonic (block : SampleBlock) (t1 t2 : Q16_16)
(h : t1 < t2) :
let e1 := detectErasureThreshold block t1
let e2 := detectErasureThreshold block t2
e1.foldl (fun acc m => acc + if m.isErased then 1 else 0) 0 ≥
e2.foldl (fun acc m => acc + if m.isErased then 1 else 0) 0 := by
-- Higher threshold detects fewer erasures
unfold detectErasureThreshold
-- ═══════════════════════════════════════════════════════════════════════════
-- §7 Verification Examples
-- ═══════════════════════════════════════════════════════════════════════════
def exampleScheme : RedundancyScheme :=
{ blockSize := 8, step1 := 5, step2 := 3, offset1 := 1, offset2 := 2 }
def exampleBlock : SampleBlock :=
{ samples := #[one, two, one, two, one, two, one, two], blockId := 0 }
#eval isValidScheme exampleScheme
-- Expected: true (5 and 3 are coprime to 8)
#eval affinePerm 8 5 1 0
-- Expected: 1
#eval affinePermInv? 8 5 1 1
-- Expected: some 0
#eval buildStreamBundle exampleScheme exampleBlock
-- Expected: Bundle with primary (identity) and two permuted streams
#eval detectErasureThreshold exampleBlock (ofNat 100)
-- Expected: No erasures (all samples < 100)
#eval recoverSample (some one) (some two) none
-- Expected: (1 + 2) / 2 = 1.5 in Q16.16
end Semantics.DspErasureCoding