# Research Stack — Plain English Intro

Proto-concept December 2025, initial concept February 2026. This document is the 5-minute version.

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## What is this, really?

A machine that takes a hard puzzle and **chews on it until the answer falls out**.

The twist: every step is double-checked by a computer program (Lean) that
mathematically proves the answer is correct. No guesswork. No "we think this
works." The computer can't cheat.

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## How it works (3 steps)

### Step 1: Give the puzzle to 8 conveyor belts

Take any puzzle — a Sudoku grid, a compression task, a physics equation,
a math problem.

Slice the puzzle into 8 parallel streams of data. Each stream runs down its
own conveyor belt, and each belt gets a unique **barcode**: one of the numbers
`1, 2, 4, 8, 16, 32, 64, 128`.

These barcodes are special: because they're powers of 2, you can add any two
and get a unique third number (3 = 1+2, but no other pair sums to 3). This
means every crossing of two belts leaves a trace that can't be faked.

### Step 2: Merge the belts until they stop changing

The 8 belts feed into each other in pairs. Every time two belts meet, they:
- Add their data together
- XOR their barcodes to produce a new crossing ID
- Record how much they changed (the "residual")

This repeats in a loop. Each pass merges the strands, records the changes,
and feeds the result back in.

Eventually the belts **stop changing**. A pass produces the same data as the
pass before. That stable state is called an **eigensolid** — think of it as
a coiled spring that has finished settling.

### Step 3: Read the receipt

The final state is a **receipt** with six numbers:
- Which barcodes crossed (the "crossing matrix")
- How much barcode budget is left (the "Sidon slack")
- How many merge passes it took
- The complete history of residuals
- A timestamp
- A flag saying "no errors occurred"

That receipt IS the answer. For compression: the receipt is the compressed
file. For a math proof: the receipt replaces pages of algebra.

The computer can reverse the receipt back into the original puzzle, proving
nothing was lost.

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## "This sounds like a normal algorithm, what's special?"

Three things:

### No rounding errors

The math uses **fixed-point numbers** (like counting pennies instead of dollars
with decimals). Every chip in the world — GPU, FPGA, CPU, phone, ASIC —
computes these numbers the same way. There is no "it works on my machine."

If this runs on a graphics card or a custom chip or an Arduino, the answer is
identical.

### No cheating

Every step is written in the Lean language. Lean is a proof checker: it is
impossible to write an incorrect proof and have Lean accept it. If the code
compiles, the math is right.

### The answer is a barcode, not a number

Instead of saying "the answer is 42," the system produces a **structural
barcode** that captures the shape of the solution. This matters because two
different puzzles with the same structure produce the same barcode — which is
how the system discovers hidden connections between unrelated things.

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## What has it actually done?

- **8 theorems** proven in Lean about the braid reaching a stable state
- **250 math equations** classified by structural type
- A compression receipt system verified in formal logic
- FPGA hardware extraction (runs on $7 dev boards)
- Connection between compression and astronomy data (DESI)
- Connection between math proofs and Sudoku solvers

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## Why Erdős Problem #336?

It's the test case that validates the whole pipeline in one small package.

The problem asks: can you build a set of numbers where the *order* (the
minimum number of terms needed to represent any large enough integer) is 2,
but the *exact order* (the minimum number that actually works for every
integer) is 3? Erdős found such a set — a union of intervals based on powers
of two.

This one problem hits every stress point the pipeline needs to survive:

| What it tests | Why it matters |
|---------------|---------------|
| **Implied infinities** | The set is infinite; the encoder must truncate it and reconstruct the tail. |
| **Two conflicting answers** | Order=2 and exact order=3 must coexist in the same layout without contradiction. |
| **Cross-domain constraint chain** | The exact-order proof depends on a coprime-number theorem — propagation must fire across multiple constraint types. |
| **Reverse verification** | After encoding and cycling to a stable state, decoding must recover the original set and both numbers. |
| **Barcode uniqueness** | The truncated set must have distinct crossing sums (Sidon injectivity). |
| **Deep structure, tiny input** | Only 3 intervals (8 numbers), but encodes an infinite construction pattern. |

Passing #336 means the pipeline handles infinities, contradictory-looking
constraints, theorem coupling, lossless round-trip, and barcode integrity —
all at once. If it passes this, it passes almost anything.

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## Where to start reading

Not this document — go deeper:

| File | What it is |
|------|-----------|
| `AGENTS.md` | The full operating manual for the project |
| `0-Core-Formalism/lean/` | The Lean formal proofs (ground truth) |
| `4-Infrastructure/` | Hardware + driver code |
| `6-Documentation/docs/` | Design docs, receipts, spec sheets |
| `shared-data/` | Generated data and artifacts |

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*This project has no corporate sponsor, no grant funding, and no team. It is a
single person's attempt to find the universal shape of an answer.*