Struct SpinGlass 

pub struct SpinGlass<W = f64> { /* private fields */ }

The Spin Glass (Ising model) problem.

Given n spin variables s_i ∈ {-1, +1}, interaction coefficients J_ij, and on-site fields h_i, minimize the Hamiltonian:

H(s) = Σ_{i<j} J_ij * s_i * s_j + Σ_i h_i * s_i

Representation

Variables are binary (0 or 1), mapped to spins via: s = 2*x - 1

• x = 0 → s = -1
• x = 1 → s = +1

Example

use problemreductions::models::optimization::SpinGlass;
use problemreductions::{Problem, Solver, BruteForce};

// Two spins with antiferromagnetic coupling J_01 = 1
let problem = SpinGlass::new(2, vec![((0, 1), 1.0)], vec![0.0, 0.0]);

let solver = BruteForce::new();
let solutions = solver.find_best(&problem);

// Ground state has opposite spins
for sol in &solutions {
    assert!(sol[0] != sol[1]); // Antiferromagnetic: opposite spins
}

Implementations

impl<W: Clone + Default> SpinGlass<W>

pub fn new( num_spins: usize, interactions: Vec<((usize, usize), W)>, fields: Vec<W>, ) -> Self

Create a new Spin Glass problem.

Arguments

• num_spins - Number of spin variables
• interactions - Coupling terms J_ij as ((i, j), value)
• fields - On-site fields h_i

pub fn without_fields( num_spins: usize, interactions: Vec<((usize, usize), W)>, ) -> Self

where W: Zero,

Create a Spin Glass with no on-site fields.

pub fn num_spins(&self) -> usize

Get the number of spins.

pub fn interactions(&self) -> &[((usize, usize), W)]

Get the interactions.

pub fn fields(&self) -> &[W]

Get the on-site fields.

pub fn config_to_spins(config: &[usize]) -> Vec<i32>

Convert binary config (0,1) to spin config (-1,+1).

impl<W> SpinGlass<W>

where W: Clone + Zero + AddAssign + Mul<Output = W> + From<i32>,

pub fn compute_energy(&self, spins: &[i32]) -> W

Compute the Hamiltonian energy for a spin configuration.

Trait Implementations

impl<W: Clone> Clone for SpinGlass<W>

fn clone(&self) -> SpinGlass<W>

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<W: Debug> Debug for SpinGlass<W>

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

Formats the value using the given formatter.

impl<'de, W> Deserialize<'de> for SpinGlass<W>

where W: Deserialize<'de>,

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl<W> Problem for SpinGlass<W>

where W: Clone + Default + PartialOrd + Num + Zero + AddAssign + Mul<Output = W> + From<i32> + 'static,

const NAME: &'static str = "SpinGlass"

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

type GraphType = SimpleGraph

The graph type this problem operates on.

type Weight = W

The weight type for this problem.

type Size = W

The type used for objective/size values.

fn num_variables(&self) -> usize

Returns the number of variables in the problem.

fn num_flavors(&self) -> usize

Returns the number of possible values (flavors) for each variable. For binary problems, this is 2.

fn problem_size(&self) -> ProblemSize

Returns metadata about the problem size.

fn energy_mode(&self) -> EnergyMode

Returns whether larger or smaller objective values are better.

fn solution_size(&self, config: &[usize]) -> SolutionSize<Self::Size>

Evaluate the solution size for a given configuration.

fn variables(&self) -> Range<usize>

Returns the range of variable indices.

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

Returns the possible flavors as a vector.

fn is_valid_config(&self, config: &[usize]) -> bool

Check if a configuration is valid for this problem.

fn solution_size_multiple( &self, configs: &[Vec<usize>], ) -> Vec<SolutionSize<Self::Size>>

Evaluate multiple configurations at once (batch evaluation).

impl<W> ReduceTo<MaxCut<W>> for SpinGlass<W>

where W: Clone + Default + PartialOrd + Num + Zero + AddAssign + From<i32> + 'static,

type Result = ReductionSGToMaxCut<W>

The reduction result type.

fn reduce_to(&self) -> Self::Result

Reduce this problem to the target problem type.

impl ReduceTo<QUBO> for SpinGlass<f64>

type Result = ReductionSGToQUBO

The reduction result type.

fn reduce_to(&self) -> Self::Result

Reduce this problem to the target problem type.

impl<W> ReduceTo<SpinGlass<W>> for CircuitSAT<W>

where W: Clone + Default + PartialOrd + Num + Zero + AddAssign + From<i32> + 'static,

type Result = ReductionCircuitToSG<W>

The reduction result type.

fn reduce_to(&self) -> Self::Result

Reduce this problem to the target problem type.

impl<W> ReduceTo<SpinGlass<W>> for MaxCut<W>

where W: Clone + Default + PartialOrd + Num + Zero + AddAssign + From<i32> + 'static,

type Result = ReductionMaxCutToSG<W>

The reduction result type.

fn reduce_to(&self) -> Self::Result

Reduce this problem to the target problem type.

impl ReduceTo<SpinGlass> for QUBO<f64>

type Result = ReductionQUBOToSG

The reduction result type.

fn reduce_to(&self) -> Self::Result

Reduce this problem to the target problem type.

impl<W> Serialize for SpinGlass<W>

where W: Serialize,

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

where __S: Serializer,

Serialize this value into the given Serde serializer.