# Singer's Theorem — Lean 4 Formalization

Forked from `d0d1/singer-theorem-lean`. This is a submodule of the Research Stack.

## Build

```bash
cd /home/allaun/Research\ Stack/0-Core-Formalism/lean/singer-theorem-lean
lake exe cache get  # ALWAYS first — Mathlib from source needs ~32 GB RAM
lake build
```

Toolchain: `leanprover/lean4:v4.29.0` (pinned in lean-toolchain).
Dependency: Mathlib v4.29.0 (locked in lake-manifest.json).

## Zero-sorry invariant

This project has zero sorries by design. Before committing:

```bash
lake build  # must pass with 0 errors
lake env lean --run Erdos30.lean 2>&1 | grep -i sorry  # no output
```

## Port status

The main Singer theorem (`singer_sidon_set`) has been ported into the Research
Stack's `Semantics.SidonSets` module. This repo is the canonical upstream.
Changes here must be mirrored to `Semantics.SidonSets` if they affect the
shared Sidon infrastructure (`IsSidon`, `IsSidonMod`, `IsIntervalSidon`).

## Rules

- Never edit `lean-toolchain` or bump Mathlib revs.
- Linter warnings are acceptable; errors and sorries are not.
- The prime-power extension (`SingerPrimePower*`) is a separate generalization;
  the core Singer proof only needs the prime case.