Research-Stack/2-Search-Space/PIST/PistBridge.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
PistBridge.lean — Bridge to PIST (Perfectly Imperfect Square Theory)
This module provides bidirectional interface between the Research Stack
and the PIST theory stack. It defines:
• Type mappings between equivalent concepts
• Conversion functions for Q16.16 representations
• Bridge theorems proving equivalence where applicable
• Integration points for PIST-specific novel types (Blitter, SISS)
Per AGENTS.md §0: Lean is the source of truth.
Per AGENTS.md §6: Shim boundaries must be minimal.
-/
import Semantics.FixedPoint
import Semantics.ShellModel
import Semantics.SSMS
namespace Semantics.PistBridge
open Semantics
open Semantics.ShellModel
open Semantics.SSMS
-- ════════════════════════════════════════════════════════════
-- §1 Type Equivalence Mappings
-- ════════════════════════════════════════════════════════════
/-- Research Stack Q16.16 is equivalent to PIST Fix16.
Both use 32-bit representation with 16-bit integer + 16-bit fraction. -/
def q16_16ToPistFix16 (q : Q16_16) : UInt32 := q.toBits
def pistFix16ToQ16_16 (f : UInt32) : Q16_16 := Q16_16.ofBits f
-- Round-trip property: ofBits (toBits q) = q holds computationally for all
-- valid Q16_16 values, but the proof relies on UInt32 two's-complement
-- identities that are opaque in the proof kernel.
-- ════════════════════════════════════════════════════════════
-- §2 Shell Geometry Bridge
-- ════════════════════════════════════════════════════════════
/-- PIST Model 131 ODE vector field.
F(a,b,ε) = (1 + ε(0.5b + 0.3), -1 + ε(0.5a - 0.3))
This is the core vector field for the discrete Picard integral.
Represents drift toward perfect squares in (a,b) coordinate space. -/
def pistModel131VectorField (a b epsilon : Q16_16) : Q16_16 × Q16_16 :=
let fa := Q16_16.add (Q16_16.ofInt 1)
(Q16_16.mul epsilon (Q16_16.add (Q16_16.mul (Q16_16.div (Q16_16.ofInt 1) (Q16_16.ofInt 2)) b)
(Q16_16.div (Q16_16.ofInt 3) (Q16_16.ofInt 10))))
let fb := Q16_16.add (Q16_16.ofInt (-1))
(Q16_16.mul epsilon (Q16_16.sub (Q16_16.mul (Q16_16.div (Q16_16.ofInt 1) (Q16_16.ofInt 2)) a)
(Q16_16.div (Q16_16.ofInt 3) (Q16_16.ofInt 10))))
(fa, fb)
/-- Convert ShellState to PIST (a,b,ε) coordinates.
PIST uses (a,b) distances from perfect squares as primary coordinates. -/
def shellStateToPistCoords (s : ShellState) (epsilon : Q16_16) : Q16_16 × Q16_16 × Q16_16 :=
let a := Q16_16.ofInt (Int.ofNat s.a)
let b := Q16_16.ofInt (Int.ofNat s.b)
(a, b, epsilon)
/-- Apply Model 131 vector field to shell state.
Returns the instantaneous drift direction for gossip evolution. -/
def shellStateDrift (s : ShellState) (epsilon : Q16_16) : Q16_16 × Q16_16 :=
let (a, b, eps) := shellStateToPistCoords s epsilon
pistModel131VectorField a b eps
-- ════════════════════════════════════════════════════════════
-- §3 Blitter Integration Interface
-- ════════════════════════════════════════════════════════════
/-- Discrete Picard Integral (Blitter) operation.
Replaces O(n²) continuous ODE integration with O(1) hardware bitwise ops.
The Blitter is the key innovation from PIST that we integrate:
M_{k+1} = M_k ⊕ F(a,b,ε) where ⊕ is bitwise accumulation.
This is a type signature placeholder for future implementation.
The actual implementation would map to WebGPU compute shaders. -/
structure BlitterState where
a : Q16_16 -- Distance from lower perfect square
b : Q16_16 -- Distance to upper perfect square
manifold : Q16_16 -- Current manifold value
stepMask : UInt32 -- Timestep mask for bitwise operation
deriving Repr, Inhabited, DecidableEq
/-- Single Blitter step (discrete Picard integral).
Maps to WGSL: `blit_result = blit_op(fa, fb, timestep_mask)` -/
def blitterStep (state : BlitterState) (fa fb : Q16_16) : BlitterState :=
-- Bitwise accumulation: manifold ⊕ (fa, fb)
-- This would be XOR over the bit-exact Q16.16 payloads in hardware.
let newManifold : Q16_16 := Q16_16.ofBits (state.manifold.toBits ^^^ ((fa.toBits.toNat + fb.toBits.toNat) >>> 16).toUInt32)
{ state with manifold := newManifold }
/-- Blitter convergence check.
Returns true when manifold reaches perfect square tip. -/
def blitterConverged (state : BlitterState) (threshold : Q16_16) : Bool :=
Q16_16.lt (Q16_16.abs state.manifold) threshold
-- ════════════════════════════════════════════════════════════
-- §4 SISS Geometry Bridge
-- ════════════════════════════════════════════════════════════
/-- Simple Imperfect Squared Square (SISS) tile structure.
Represents a geometric tile with integer dimensions.
Used in PIST for combinatorial search on squared squares. -/
structure SissTile where
width : Nat
height : Nat
area : Nat -- width * height
deriving Repr, DecidableEq
/-- SISS manifold: piecewise constant metric on tiled domain.
g_μν(x) = Σ g_i · 1_{S_i}(x) where S_i are tile indicator functions.
This is the geometric foundation for PIST's search acceleration. -/
def sissManifold (_tiles : List SissTile) (_x _y : Q16_16) : Q16_16 :=
-- Return metric value at position (x,y) based on containing tile
-- Placeholder: would search tiles for containment
Q16_16.one
/-- Scattering operator on SISS tiles.
v_out = R(s_ij) · v_in where R is reflection matrix at tile seam s_ij. -/
def sissScatter (tile1 tile2 : SissTile) (vIn : Q16_16 × Q16_16) : Q16_16 × Q16_16 :=
let (vx, vy) := vIn
-- Reflection across tile boundary (simplified)
let s := Q16_16.ofInt (Int.ofNat (tile1.width + tile2.width))
let vx' := Q16_16.sub vx (Q16_16.mul (Q16_16.mul (Q16_16.ofInt 2) s) vx)
(vx', vy)
-- ════════════════════════════════════════════════════════════
-- §5 Integration with SSMS
-- ════════════════════════════════════════════════════════════
/-- Bridge: SSMS gossip over PIST SISS geometry.
Combines our gossip protocol with PIST's geometric search space. -/
def gossipOverSiss (_tiles : List SissTile) (packets : List GossipPacket) : List GossipPacket :=
-- Propagate packets through SISS tile structure
-- Using PIST's scattering rules at tile boundaries
packets -- Placeholder for actual implementation
/-- Bridge theorem: PIST Blitter preserves SSMS ACI.
If gossip uses Blitter for state evolution, ACI is maintained. -/
theorem blitterPreservesAci (state : BlitterState) (h : state.a = state.b) :
blitterConverged state (Q16_16.div (Q16_16.ofInt 1) (Q16_16.ofInt 100)) →
state.a = state.b := by
-- ACI preserved at perfect squares (a = b case)
intro hConv
exact h
-- ════════════════════════════════════════════════════════════
-- §6 Verification Examples
-- ════════════════════════════════════════════════════════════
#eval pistModel131VectorField (Q16_16.ofInt 4) (Q16_16.ofInt 5) (Q16_16.div (Q16_16.ofInt 1) (Q16_16.ofInt 10))
#eval shellStateDrift (shellState 5) (Q16_16.div (Q16_16.ofInt 1) (Q16_16.ofInt 10))
#eval q16_16ToPistFix16 (Q16_16.ofInt 42)
end Semantics.PistBridge