Research-Stack/0-Core-Formalism/lean/Semantics/Semantics/BraidBitwiseODE.lean
Brandon Schneider e0df130453 feat: 12 math enhancements — Q16 LUT, braid VCN encoder, FPGA Verilog, FFT, crypto
Pipeline:
- q16_lut_vcn.py: Q16_16 LUT generation + VCN frame encoding (8 ops)
- braid_vcn_encoder.py: Delta+RLE → RS ECC → ChaCha20 → VCN → MKV
- braid_search.py: Sidon set slots, soliton search, QUBO optimization
- test_braid_pipeline.py: 67 tests covering full round-trip

WebGPU/Scripts:
- braid_fft.wgsl: Cooley-Tukey radix-2 FFT on phase vectors
- reed_solomon_vcn.py: Reed-Solomon ECC for VCN frame data
- chacha20_braid.py: ChaCha20 encryption + key derivation
- polynomial_commitment.py: KZG scheme for receipt verification

Lean:
- BraidBitwiseODE.lean: XOR crossing, O(1) integration, 2 proved theorems

FPGA (Tang Nano 9K):
- q16_lut_core.v: 8-op arithmetic, 2-stage pipeline, BRAM reciprocal
- braid_crossing_core.v: 4-stage crossing residual, 7 Q16 instances
- Testbenches with edge cases + VCD dumps
2026-05-28 14:49:26 -05:00

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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
BraidBitwiseODE.lean — Bitwise ODE integration for braid crossings
Replaces continuous O(1) integration with XOR-based bitwise operations
on Q16.16 fixed-point values. Pattern derived from PistBridge's BlitterState
discrete Picard integral.
Hierarchy: PistBridge BlitterState → BraidBitwiseODE crossing + integration
Per AGENTS.md §0: Lean is the source of truth.
-/
import Semantics.FixedPoint
import Semantics.BraidStrand
namespace Semantics.BraidBitwiseODE
open Semantics
open Semantics.FixedPoint
open Semantics.BraidStrand
-- ════════════════════════════════════════════════════════════
-- §1 Bitwise Crossing Operation
-- ════════════════════════════════════════════════════════════
/-- XOR-based braid crossing step.
Models a crossing between two strands as a bitwise operation
on their Q16.16 payloads. Parity of each strand determines
the crossing sign (over/under).
Pattern: M_{k+1} = M_k ⊕ F(a,b,ε) from PistBridge §3. -/
def bitwiseCrossStep (a b : BraidStrand) : BraidStrand :=
let pa := a.phaseAcc
let pb := b.phaseAcc
-- XOR the phase accumulations' bit patterns
let newX := Q16_16.ofBits (pa.x.toBits ^^^ pb.x.toBits)
let newY := Q16_16.ofBits (pa.y.toBits ^^^ pb.y.toBits)
-- Swap parity to indicate crossing
let newParity := !a.parity
-- Accumulate residue: XOR with crossing signal
let crossSignal := Q16_16.ofBits (a.residue.toBits ^^^ b.residue.toBits)
{ phaseAcc := { x := newX, y := newY }
, parity := newParity
, slot := a.slot
, residue := crossSignal
, jitter := a.jitter
, bracket := a.bracket }
-- ════════════════════════════════════════════════════════════
-- §2 O(1) ODE Integration Step
-- ════════════════════════════════════════════════════════════
/-- Discrete Picard integral: O(1) bitwise ODE integration.
Replaces continuous ODE solver with a single bitwise accumulation.
From PistBridge: M_{k+1} = M_k ⊕ (state + input) >> 16
This is the Blitter operation: accumulate state and input via
XOR with right-shift, giving a single-step ODE approximation. -/
def bitwiseODEIntegrate (state : Q16_16) (input : Q16_16) : Q16_16 :=
-- Combine state and input via addition, then XOR-accumulate
let combined := Q16_16.ofNat ((state.toBits.toNat + input.toBits.toNat) % (2^32))
-- Right-shift by 16 to extract the integer portion effect
let shifted := Q16_16.ofBits ((combined.toBits.toNat >>> 16).toUInt32)
-- XOR with original state for the Blitter accumulation
Q16_16.ofBits (state.toBits ^^^ shifted.toBits)
/-- Multi-step bitwise ODE integration.
Applies the bitwise ODE integrator iteratively over a sequence
of input values, accumulating into the state. -/
def bitwiseODEIntegrateSeq (state : Q16_16) (inputs : List Q16_16) : Q16_16 :=
inputs.foldl bitwiseODEIntegrate state
-- ════════════════════════════════════════════════════════════
-- §3 Braid Strand ODE Integration
-- ════════════════════════════════════════════════════════════
/-- Integrate a braid strand's phase accumulation via bitwise ODE.
Applies the discrete Picard integral to both x and y components
of the strand's phase vector. -/
def integrateStrand (strand : BraidStrand) (input : Q16_16) : BraidStrand :=
let newX := bitwiseODEIntegrate strand.phaseAcc.x input
let newY := bitwiseODEIntegrate strand.phaseAcc.y input
{ strand with phaseAcc := { x := newX, y := newY } }
/-- Two-strand crossing with integrated ODE step.
Combines bitwiseCrossStep with ODE integration in a single
atomic operation: cross, then integrate the result. -/
def crossingODEStep (a b : BraidStrand) : BraidStrand × BraidStrand :=
let crossed := bitwiseCrossStep a b
let integrated := integrateStrand crossed a.residue
(integrated, crossed)
-- ════════════════════════════════════════════════════════════
-- §4 Fixed-Point Invariants
-- ════════════════════════════════════════════════════════════
/-- The bitwise ODE integrator preserves Q16.16 range.
Since all operations (XOR, shift, ofBits) produce valid Q16_16
values, the output is always in the representable range. -/
theorem bitwise_ode_preserves_range (state input : Q16_16) :
q16MinRaw ≤ (bitwiseODEIntegrate state input).toInt ∧
(bitwiseODEIntegrate state input).toInt ≤ q16MaxRaw := by
unfold bitwiseODEIntegrate
exact ⟨(Q16_16.ofBits _).property.left, (Q16_16.ofBits _).property.right⟩
/-- Bitwise cross step preserves strand slot identity.
The slot field is carried through from the first strand. -/
theorem cross_step_preserves_slot (a b : BraidStrand) :
(bitwiseCrossStep a b).slot = a.slot := by
unfold bitwiseCrossStep
rfl
-- ════════════════════════════════════════════════════════════
-- §5 Convergence (Placeholder)
-- ════════════════════════════════════════════════════════════
/-- TODO(lean-port): Prove that bitwise ODE integration converges
for bounded inputs. This requires showing that repeated application
of `bitwiseODEIntegrate` reaches a fixed point (absorbing state).
Conjecture: for any state s and bounded input sequence,
bitwiseODEIntegrateSeq reaches a fixed point after at most
32 steps (the bit width of Q16.16). -/
theorem bitwise_ode_correct (state : Q16_16) (h : state.toInt = 0) :
bitwiseODEIntegrate state state = state := by
unfold bitwiseODEIntegrate
simp [h, Q16_16.ofBits, Q16_16.toBits, Q16_16.ofNat]
sorry -- TODO(lean-port): requires Q16.16 bit-level identity proof
-- ════════════════════════════════════════════════════════════
-- §6 Verification Examples
-- ════════════════════════════════════════════════════════════
#eval bitwiseODEIntegrate (Q16_16.ofInt 2) (Q16_16.ofInt 3)
#eval bitwiseODEIntegrate (Q16_16.ofInt 0) (Q16_16.ofInt 0)
end Semantics.BraidBitwiseODE