---
title: "PBOutput"
description: "Answers in the format of the Pseudo-Boolean competition."
---

> Documentation Index
> Fetch the complete documentation index at: https://docs.cpbenchy.com/llms.txt
> Use this file to discover all available pages before exploring further.

# PBOutput

## What it does

Writes what a solver in the [Pseudo-Boolean competition](https://www.cril.univ-artois.fr/PB26/) prints,
for each run on an OPB instance. The solution is a line with every variable as a literal:

```
o -7
o -9
s OPTIMUM FOUND
v x1 x2 -x3 x4
```

Each competition specifies what a solver prints:
- `o` lines with each better objective value, while it solves
- an `s` line with its answer: `OPTIMUM FOUND`, `SATISFIABLE`, `UNSATISFIABLE` or `UNKNOWN`
- `v` lines with the solution

The output goes to each run's `logs/<run_id>.pb.out`, written inside the measured run, as a
competition solver would print it, so it costs the run the time it would cost in the competition. A run
that is killed keeps its `o` lines. Under [`cpbenchy solve`](/library/solve/), the output goes to stdout,
where competitions read it.

Variables that occur in no constraint still get a value, from the number of variables in the
instance's header (`* #variable= ...`).

## Use it

```python
import cpbenchy
from cpbenchy import observers

cpbenchy.run("pb/", solvers=["exact", "ortools"], time_limit=60, plugins=[observers.PBOutput()])
```

```sh
cpbenchy run pb/ -s exact -s ortools -t 60 -p cpbenchy.observers:PBOutput
```

The [PB rules](/library/pb26/) enable it, with the competition's limits.

## What it records

| | |
|---|---|
| `logs/<run_id>.pb.out` | the competition output |

## Implementation

Source: https://docs.cpbenchy.com/library/pb-output/index.mdx