https://github.com/night-crawler/nnf

Negation Normal Form manipulation library
https://github.com/night-crawler/nnf

cnf nnf tseitin-transformation

Last synced: 8 days ago
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Negation Normal Form manipulation library

• Host: GitHub
• URL: https://github.com/night-crawler/nnf
• Owner: night-crawler
• License: mit
• Created: 2022-12-26T20:40:56.000Z (almost 2 years ago)
• Default Branch: main
• Last Pushed: 2023-04-19T11:50:05.000Z (over 1 year ago)
• Last Synced: 2024-05-22T21:34:42.836Z (6 months ago)
• Topics: cnf, nnf, tseitin-transformation
• Language: Rust
• Homepage:
• Size: 30.3 KB
• Stars: 1
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Awesome Lists containing this project

• awesome-rust-formalized-reasoning - nnf - Negation Normal Form manipulation library. (Projects / Libraries)

README

        
# nnf

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

[![Rust](https://github.com/night-crawler/nnf/actions/workflows/rust.yml/badge.svg?branch=main)](https://github.com/night-crawler/nnf/actions/workflows/rust.yml)

[![MIT licensed](https://img.shields.io/badge/license-MIT-blue.svg)](./LICENSE)

Negation Normal Form manipulation library

### Macro & bit operations

```rust

fn sample() {

    let a = Nnf::Var("a", true);

    let b = var!("b", false);

    let or = or!(a.clone(), b.clone());

}

```

### Simple operations optimization

```rust

assert_eq!(and!("a") & and!("b"), and!("a", "b"));

assert_eq!(and!("a") | and!("b"), or!("a", "b"));

```

### Tseitin Transform (NNF -> CNF)

```rust

fn transform(sentence: Nnf<&'static str>) -> Nnf<&'static str> {

    let mut counter = 0;

    let transformer = TseitinTransform::new(|_| {

        let name: &'static str = Box::leak(Box::new(format!("aux_{}", counter)));

        counter += 1;

        var!(name)

    });

    transformer.transform(sentence)

}

fn test() {

    let sentence = or!(

        and!(

            var!("a"),

            and!("b", "c")

        ),

        and!(

            or!("!d", "e"),

            and!("f", "!g")

        )

    );

    assert!(!sentence.is_cnf(), "Expression is not a cnf yet");

    let sentence = transform(sentence);

    assert!(sentence.is_cnf(), "Expression must be in the cnf form after transformation");

    assert_eq!(

        sentence,

        and!(

            or!("a", "!aux_1"),

            or!("aux_0", "!aux_1"),

            or!("aux_1", "aux_4"),

            or!("aux_2", "!aux_4"),

            or!("aux_3", "!aux_4"),

            or!("!aux_0", "b"),

            or!("!aux_0", "c"),

            or!("aux_3", "d"),

            or!("aux_3", "!e"),

            or!("!aux_2", "f"),

            or!("!aux_2", "!g"),

            or!("!a", "!aux_0", "aux_1"),

            or!("!aux_2", "!aux_3", "aux_4"),

            or!("aux_0", "!b", "!c"),

            or!("!aux_3", "!d", "e"),

            or!("aux_2", "!f", "g")

        )

    );

}

```

## Parse Tree

### Macro support

```rust

fn test() {

    let root = ExpressionNode::Not(

        ExpressionNode::And(

            ExpressionNode::Or(

                ExpressionNode::Leaf(1).into(),

                ExpressionNode::Leaf(2).into(),

            ).into(),

            ExpressionNode::And(

                ExpressionNode::Leaf(3).into(),

                ExpressionNode::Leaf(4).into(),

            ).into(),

        ).into());

    let root = e_not!(

    e_and!(

        e_or!(

            e_leaf!(1),

            e_leaf!(2)

        ),

        e_and!(

            e_leaf!(3),

            e_leaf!(4)

        )

    )

);

}

```

### Expression Tree to NNF conversion (De Morgan's Law, double negation, etc.)

```rust

assert_eq!(

    e_not!(e_leaf!(true) & e_leaf!(true)).to_nnf(),

    e_or!(e_leaf!(false), e_leaf!(false))

);

assert_eq!(

    e_not!(e_leaf!(true) | e_leaf!(true)).to_nnf(),

    e_and!(e_leaf!(false), e_leaf!(false))

);

assert_eq!(

    !ExpressionNode::Not(e_or!(e_leaf!(true), e_leaf!(true)).into()),

    e_or!(e_leaf!(true), e_leaf!(true))

);

```

## (Optional) Render / Graphviz

```rust

fn test() {

    let sentence = or!(

            and!(

                var!("a"),

                and!("b", "c")

            ),

            and!(

                or!("!d", "e"),

                and!("f", "!g")

            )

        );

    assert!(!sentence.render().is_empty());

}

```