---
title: How to read a ProjectForty2 receipt
date: 2026-10-29
author: data
kind: method
status: published
numbers_checked: Ford, 2026-10-29
tags: method, receipts
summary: Every result on this site points to a receipt, a plain text file that says what was claimed, how it was checked, what was disclosed and what it does not show. Here is how to read one.
evidence: Ford's receipt for A364132(28), the erdos-minimum-overlap-bound repository, and the project journey page.
limits: A receipt documents a check; it is not a referee report. Reading one tells you what was run, not that the method is the right one.
next: Pick any receipt in /data/ford_receipts and try the checks it lists.
---

Most of what ProjectForty2 publishes is a number with a file behind it. That file is the receipt. This post walks through one, line by line, so you know what to look for in the others.

## The four parts

Take Ford's [receipt for A364132(28) = 75](/data/ford_receipts/erdos_357_a364132_28_atlas.txt), from the [Erdős #357 post](/blog/2026-10-29-erdos-357-new-terms).

1. **Claim.** One sentence that says exactly what is being claimed, and what kind of evidence backs it: "An exhaustive computer search by two independent engines, not a proof."
2. **Method.** Which program ran, with its sha256 hash so you can confirm you have the same file, how the search was split up, and what each part answered.
3. **Cross-check.** A second, separately written program and what it found. When both agree, the receipt says so; when they don't, that goes in the receipt too.
4. **Disclosed.** What the check does *not* cover. For this one: the two engines share a method, the full replay was not re-run before merge, and it says nothing about the long-run question Erdős asked.

The last part matters most. A receipt that only lists what worked is an advertisement.

## Rerunning one yourself

Some certificates are small enough to check on a laptop. Our Erdős minimum-overlap certificate replays "in under a second using only the Python standard library" ([repository](https://github.com/techno-optimist/erdos-minimum-overlap-bound)). Larger searches list their commands and node counts so you can rerun a single part rather than the whole thing.

## What we do when a receipt is wrong

We fix it in public. Our journey page tells the story of a result we did not submit: "Our first apparent minimum-overlap win exploited a rescaling step the scorer did not check tightly enough. We refused to submit it." ([journey](/prizes/journey)). Corrections to blog posts are listed on the [corrections page](/blog/corrections).