Struct PrimeAttributeName 

pub struct PrimeAttributeName { /* private fields */ }

Prime Attribute Name decision problem.

Given a set A = {0, 1, …, n-1} of attribute names, a collection F of functional dependencies on A, and a specified attribute x in A, determine whether x is a prime attribute – i.e., whether there exists a candidate key K for <A, F> such that x is in K.

A candidate key is a minimal set K of attributes whose closure under F equals A. An attribute is prime if it belongs to at least one candidate key.

This is a classical NP-complete problem from relational database theory (Garey & Johnson SR28, Lucchesi & Osborne 1978).

Example

use problemreductions::models::set::PrimeAttributeName;
use problemreductions::{Problem, Solver, BruteForce};

// 6 attributes, FDs: {0,1}->rest, {2,3}->rest, {0,3}->rest
let problem = PrimeAttributeName::new(
    6,
    vec![
        (vec![0, 1], vec![2, 3, 4, 5]),
        (vec![2, 3], vec![0, 1, 4, 5]),
        (vec![0, 3], vec![1, 2, 4, 5]),
    ],
    3,
);

// {2, 3} is a candidate key containing attribute 3
assert!(problem.evaluate(&[0, 0, 1, 1, 0, 0]));

let solver = BruteForce::new();
let solution = solver.find_witness(&problem);
assert!(solution.is_some());

Implementations

impl PrimeAttributeName

pub fn new( num_attributes: usize, dependencies: Vec<(Vec<usize>, Vec<usize>)>, query_attribute: usize, ) -> Self

Create a new Prime Attribute Name problem.

Panics

Panics if query_attribute >= num_attributes, if any attribute index in a dependency is out of range, or if any LHS is empty.

pub fn num_attributes(&self) -> usize

Get the number of attributes.

pub fn num_dependencies(&self) -> usize

Get the number of functional dependencies.

pub fn query_attribute(&self) -> usize

Get the query attribute index.

pub fn dependencies(&self) -> &[(Vec<usize>, Vec<usize>)]

Get the functional dependencies.

pub fn compute_closure(&self, attrs: &[bool]) -> Vec<bool>

Compute the attribute closure of a set under the functional dependencies.

Starting from the given boolean mask of attributes, repeatedly applies all functional dependencies until a fixpoint is reached.

Trait Implementations

impl Clone for PrimeAttributeName

fn clone(&self) -> PrimeAttributeName

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for PrimeAttributeName

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for PrimeAttributeName

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Problem for PrimeAttributeName

const NAME: &'static str = "PrimeAttributeName"

Base name of this problem type (e.g., “MaximumIndependentSet”).

type Value = Or

The evaluation value type.

fn dims(&self) -> Vec<usize>

Configuration space dimensions. Each entry is the cardinality of that variable.

fn evaluate(&self, config: &[usize]) -> Or

Evaluate the problem on a configuration.

fn variant() -> Vec<(&'static str, &'static str)>

Returns variant attributes derived from type parameters.

fn num_variables(&self) -> usize

Number of variables (derived from dims).

fn problem_type() -> ProblemType

Look up this problem’s catalog entry.

impl Serialize for PrimeAttributeName

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl DeclaredVariant for PrimeAttributeName