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https://github.com/krobelus/rate

DRAT/DPR proof checker
https://github.com/krobelus/rate

proof-checker rust sat-solver verification

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DRAT/DPR proof checker

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README 

        
# rate



[![crates.io](https://img.shields.io/crates/v/rate.svg)](https://crates.io/crates/rate)

[![CircleCI branch](https://img.shields.io/circleci/project/github/krobelus/rate/master.svg)](https://circleci.com/gh/krobelus/rate/tree/master)

![](https://img.shields.io/crates/l/rate.svg)



This is a proof checker that can verify proofs for [SAT

instances](https://en.wikipedia.org/wiki/Boolean_satisfiability_problem),

just like fellow checkers

[`drat-trim`](https://github.com/marijnheule/drat-trim),

[`dpr-trim`](https://github.com/marijnheule/dpr-trim) or

[`gratgen`](http://www21.in.tum.de/~lammich/grat/).  The notable

difference is that `rate` does not [ignore deletions of unit

clauses](https://github.com/marijnheule/drat-trim#clause-deletion-details)

by default.  You can cite our [CPP 2020 conference paper] (bibtex record

[here](https://dblp.uni-trier.de/rec/bibtex/conf/cpp/AltmanningerP20))

which describes the problem that `rate` tries to solve.



# Features

- check [DRAT](http://www.cs.cmu.edu/~mheule/publications/drat-trim.pdf)

  proofs (default) and

  [DPR](http://www.cs.cmu.edu/~mheule/publications/spr.pdf) proofs (file

  extension`.pr` or `.dpr`)

- competitive performance (faster than `drat-trim` and `dpr-trim`, almost as

  fast as `gratgen`)

- output a trimmed proof as DRAT, DPR, LRAT or GRAT after verifying a proof

- check and output a SICK certificate of incorrectness after rejecting a proof

- optionally ignore unit deletions for compatibility with `drat-trim`

  (flag `--skip-unit-deletions`)

- transparently read compressed input files (Gzip, Zstandard, Bzip2, XZ, LZ4)

- detect and report many errors like numeric overflows

- mostly safe Rust, should not have any undefined behavior



# Installation



Install [Rust](https://www.rust-lang.org/en-US/install.html).  Recent versions

of stable Rust are supported (1.36 or later).



## Stable version



Releases are hosted on [crates.io](https://crates.io/) and can be

installed using `cargo`, Rust's package manager.



```sh

$ cargo install rate --force

```



After this has finished compiling, it will place the `rate` binary in

`~/.cargo/bin/`.



## Building from source



Alternatively, you can install the development version from a checkout of this

repository:



```sh

$ git clone https://github.com/krobelus/rate

$ cd rate

$ cargo install --path ./rate --force

```



# Usage



Run the proof checker like this:

```sh

$ rate formula.cnf proof.drat

```



Whenever the proof is accepted, this will exit with code 0 after printing

`s VERIFIED` and some metrics. See `rate --help` for more options.



## SICK certificates



If `rate` rejects a proof, it checks a certificate of incorrectness that

contains information on which proof step failed and why.  The certificate

can be written to a file with the `-S` option and checked separately with

the `sick-check` binary which is much faster than a full proof checker

(install `sick-check` using `cargo install rate-sick-check` for a stable

version, or `cargo install --path rate-sick-check` to install from a

local checkout). These certificates are useful to protect against bugs

in the checker code.



## Other utilities



Install the crate `rate-proof-utils` (just like `rate` or

`rate-sick-check`) for some binaries that can be useful when working

with clausal proofs:



- `drat2bdrat` and `bdrat2drat` convert a DRAT proof to the [Binary DRAT Format]

  and vice versa. Also works for DPR proofs.

- `apply-proof` applies a proof up to a given proof step, and outputs the

  accumulated formula as well as the rest of the proof. This can be very

  useful for delta-debugging a tool that works with proofs.



[Binary DRAT Format]: 



# Unexpected rejections



If you are using a solver based on

[MiniSat](https://github.com/niklasso/minisat), then your proof might

be rejected by `rate` while it is accepted by other checkers, like

`drat-trim`. This is because the proof can contain some clause deletions

that are ignored by other checkers. There are two options:



1. Use `rate --skip-unit-deletions` to make it behave like other checkers.



2. Alternatively, you can patch your solver to not generate those extra

deletions.  This will make the proof valid for every checker.  Look for

`reason deletions shrinking trail` in the output of `rate`; this is the

number of deletions in the proof that delete information - it should

probably be zero, unless you are using certain advanced inprocessing

techniques.  Example patches that avoid these deletions: MiniSat

([1](https://github.com/krobelus/minisat/commit/keep-locked-clauses) or

[2](https://github.com/krobelus/minisat/commit/add-unit-before-deleting-locked-clause))

and `MapleLCMDistChronoBT`

([1](https://github.com/krobelus/MapleLCMDistChronoBT/commit/keep-locked-clauses)

or

[2](https://github.com/krobelus/MapleLCMDistChronoBT/commit/add-unit-before-deleting-locked-clause)).



# Caveats



Please note that `rate` accepts proofs that are technically not fully

correct.  Just like other checkers, we perform some transformations

on the proof before actually verifying the proofs steps.  This is done

to improve performance.  These transformations can ignore unnecessary

clauses or proof steps.  These are effectively removed from the formula

or proof, respectively.  This means that `rate` might accept a proof

that contains lemmas that are not valid inferences, but this should

never happen for satisfiable formulas.



Here are the transformations we do:

- If `--skip-unit-deletions` is specified, then deletions of clauses that

  are unit with respect to the accumulated formula are ignored, as in

  `drat-trim` and `gratgen`.

- When traversing the proof, we stop as soon as a conflict is inferred.

  Any proof steps thereafter are ignored.  This means that an explicit empty

  clause at the end of the proof is not required.

- Clauses and lemmas that are not part of the reason for above conflict

  are ignored, even if they could be resolution candidates, find an explanation

  why this is sound [here].

- RAT checks are done upon every possible pivot and not just the first literal

  in a clause, unless `--assume-pivot-is-first` is specified.



[here]: 



# Tests



Run unit tests and the system test suite, respectively:



```sh

cargo test && ./test.py

```



You can also selectively run tests, for example use `./test.py -k default

benchmarks/crafted benchmarks/sadical/add4.cnf` to only run test functions

matching `default` on the crafted benchmarks and on `add4.{cnf,dpr}`. See

`./test.py -h` for more options.



Above tests require

- `python3` (version 3.6 or above)

- optionally any of the following executables:

  - [`lrat-check`](https://github.com/acl2/acl2/tree/master/books/projects/sat/lrat)

    to validate the produced LRAT proofs.

  - [`pr2drat`](https://github.com/marijnheule/pr2drat) to produce

    DRAT and LRAT proofs from PR proofs.

  - `gratchk` to validate produced GRAT proofs.

  - If any of `drat-trim`, `rupee`, or `gratgen` are executable they will be

    run on the benchmarks and their verdicts will be compared to the output of

    `rate`.



You can use the [docker

image](https://cloud.docker.com/repository/docker/krobelus/rate-test-environment)

used by our [CI](.circleci/config.yml) which contains [builds of above

dependencies](scripts/test-environment/).



# Documentation



Refer to our [CPP 2020 conference paper] or my [thesis] for some

background information.



[CPP 2020 conference paper]: 

[thesis]: 



The source code includes an abundance of doc comments. Use this command

to turn them into internal documentation at `target/doc/rate*/index.html`.

```sh

$ cargo doc --document-private-items --no-deps

```



# Contributing



Please let us know if `rate` behaves in a way that is unexpected to you,

or if you need some feature.  We currently do not guarantee stability of the

library modules in `rate-common` (only the binaries are considered an API),

but we can integrate more tools that work on proofs in this repository.



# Roadmap



Some possible improvements:



- expose a Rust (and possibly C) API

- support other clausal proof formats

- compute other features about clausal proofs (e.g. the lifespan of clauses)

- speed up handling of reason clause deletions that do not shrink the trail

- speed up RAT checks by caching resolution candidates