---
title: "formulations.py"
description: "Compares different ways of modelling the same problem, without any instance files."
---

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# formulations.py

## What it does

Compares formulations of your own model on generated instances: no instance files at all. The instances
are sizes, and a loader with an argument builds the model inside the run: N-Queens with AllDifferent
constraints, or with a `!=` between every pair of queens. Each formulation is a separate entry of one
experiment, so the results stay apart.

## Use it

```sh
python examples/scripts/formulations.py --sizes 8 32 64 --solvers ortools exact --time-limit 30
```

## Options

| Argument | |
|---|---|
| `--sizes` | the board sizes |
| `--solvers` | the solvers to compare |
| `--time-limit` | seconds per run |
| `--out` | output directory |

## Implementation

Source: https://docs.cpbenchy.com/examples/formulations/index.mdx